Journal articles: 'Quasars. 0'

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Yue, Minghao, Xiaohui Fan, Jinyi Yang, and Feige Wang. "A Mock Catalog of Gravitationally-lensed Quasars for the LSST Survey." Astronomical Journal 163, no. 3 (February 22, 2022): 139. http://dx.doi.org/10.3847/1538-3881/ac4cb0.

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Abstract We present a mock catalog of gravitationally-lensed quasars at z qso < 7.5 with simulated images for the Rubin Observatory Legacy Survey of Space and Time (LSST). We adopt recent measurements of quasar-luminosity functions to model the quasar population, and use the CosmoDC2 mock galaxy catalog to model the deflector galaxies, which successfully reproduces the observed galaxy-velocity dispersion functions up to z d ∼ 1.5. The mock catalog is highly complete for lensed quasars with Einstein radius θ E > 0.″07 and quasar absolute magnitude M i < − 20. We estimate that there are ∼103 lensed quasars discoverable in current imaging surveys, and LSST will increase this number to ∼ 2.4 × 103. Most of the lensed quasars have image separation Δθ > 0.″5, which will at least be marginally resolved in LSST images with seeing of ∼0.″7. There will be ∼200 quadruply-lensed quasars discoverable in the LSST. The fraction of quad lenses among all discoverable lensed quasars is about ∼10%–15%, and this fraction decreases with survey depth. This mock catalog shows a large diversity in the observational features of lensed quasars, in terms of lensing separation and quasar-to-deflector flux ratio. We discuss possible strategies for a complete search of lensed quasars in the LSST era.

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Dultzin-Hacyan, Deborah, Paola Marziani, C. Alenka Negrete, and Jack W. Sulentic. "Quasar evolution: black hole mass and accretion rate determination." Proceedings of the International Astronomical Union 2, S238 (August 2006): 83–86. http://dx.doi.org/10.1017/s1743921307004735.

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AbstractAccurate measurements of emission line properties are crucial to understand the physics of the broad line region in quasars. This region consists of warm gas that is closest to the quasar central engine and has not been spatially resolved for almost all sources. We present here an analysis of optical and IR data for a large sample of quasars, covering the Hi Hβ spectral region in the redshift range 0 ≲ z ≲ 2.5. Spectra were interpreted within the framework of the the so-called “eigenvector 1” parameter space, which can be viewed as a tentative H-R diagram for quasars. We stress the lack of spectral evolution in the low ionization lines of quasars, with prominent Fe ii emission also at z ≳ 2. We also show how selection effects influence the ability to find quasars radiating at low Eddington ratio in flux-limited surveys. The quasar similarity at different redshift is probably due to the absence of super-Eddington radiators (at least within the caveats of black hole mass and Eddington ratio determination discussed in this paper) as well as to the limited Eddington ratio range within which quasars seem to radiate.

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García-Vergara, Cristina, Matus Rybak, Jacqueline Hodge, Joseph F. Hennawi, Roberto Decarli, Jorge González-López, Fabrizio Arrigoni-Battaia, Manuel Aravena, and Emanuele P. Farina. "ALMA Reveals a Large Overdensity and Strong Clustering of Galaxies in Quasar Environments at z ∼ 4." Astrophysical Journal 927, no. 1 (March 1, 2022): 65. http://dx.doi.org/10.3847/1538-4357/ac469d.

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Abstract We present an Atacama Large Millimeter/submillimeter Array (ALMA) survey of CO(4–3) line emitting galaxies in 17 quasar fields at z ∼ 4 aimed at performing the first systematic search of dusty galaxies in high-z quasar environments. Our blind search of galaxies around the quasars results in five CO emitters with S/N ≥ 5.6 within a projected radius of R ≲ 1.5 h −1 cMpc and a velocity range of δv = ±1000 km s−1 around the quasar. In blank fields, we expect to detect only 0.28 CO emitters within the same volume, implying a total overdensity of 17.6 − 7.6 + 11.9 in our fields, and indicating that quasars trace massive structures in the early universe. We quantify this overdensity by measuring the small-scale clustering of CO emitters around quasars, resulting in a cross-correlation length of r 0 , QG = 8.37 − 2.04 + 2.42 h − 1 cMpc, assuming a fixed slope γ = 1.8. This contradicts the reported mild overdensities (x1.4) of Lyα emitters (LAEs) in the same fields at scales of R ≲ 7 h −1 cMpc, which are well described by a cross-correlation length 3.0 − 1.4 + 1.5 times lower than that measured for CO emitters. We discuss some possibilities to explain this discrepancy, including low star formation efficiency, and excess of dust in galaxies around quasars. Finally, we constrain, for the first time, the clustering of CO emitters at z ∼ 4, finding an autocorrelation length of r 0,CO = 3.14 ±1.71 h −1 cMpc (with γ = 1.8). Our work, together with the previous study of LAEs around quasars, traces simultaneously the clustering properties of both optical and dusty galaxy populations in quasars fields, stressing the importance of multiwavelength studies, and highlighting important questions about galaxy properties in high-z dense environments.

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Yee, H. K. C., and Richard F. Green. "The association of galaxy clusters with moderately-high-redshift quasars." Symposium - International Astronomical Union 119 (1986): 481–87. http://dx.doi.org/10.1017/s0074180900153239.

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CCD images of quasars having redshifts between 0.3 and 0.65 are analyzed to study the association of galaxies with quasars. Average luminosity functions (LF) of the excess galaxies associated with the radio-loud quasars are determined. It is found that for the sub-sample with z>0.55, there is a significant brightening of the characteristic magnitude M*, if qo is assumed to be 0. Comparing computed quasar-galaxy spatial-covariance amplitudes, we can conclude, at the 0.025 significance level, that the spatial-covariance amplitudes of the sub-sample with z>0.55 are greater than those of the lower redshift quasars. This indicates that there has been a strong evolution of preferred sites for bright radio-loud quasars, implying some number-density evolution of quasars has taken place, and that some rich clusters at z∼0.6, in comparison with the local rich clusters, have significantly different physical conditions.

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Ubachukwu, A. A., and J. N. Ogwo. "Luminosity Selection Effects and Linear Size Evolution in the Quasar/Galaxy Unification Scheme." Australian Journal of Physics 51, no. 1 (1998): 143. http://dx.doi.org/10.1071/p97012.

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The implications of linear size evolution and luminosity selection effects in the quasar/galaxy unification scheme have been investigated. We show that both radio galaxies and quasars undergo similar size evolution above some low redshift cut-off zc = 0·2–0·3. However, this evolution can be attributed largely to the strong luminosity selection effects present in the sample. We also observe that there is a marked difference in the luminosity–redshift slope between low and high redshift sources, which may be responsible for the conflicting results in the literature as to whether or not radio galaxies and quasars have similar linear size versus luminosity/redshift relationships. Our present result seems consistent with the quasar/galaxy unification scheme in which the two classes of object are expected to have similar linear size versus luminosity/redshift relationships.

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Shen, Xuejian, Philip F. Hopkins, Claude-André Faucher-Giguère, D. M. Alexander, Gordon T. Richards, Nicholas P. Ross, and R. C. Hickox. "The bolometric quasar luminosity function at z = 0–7." Monthly Notices of the Royal Astronomical Society 495, no. 3 (January 2020): 3252–75. http://dx.doi.org/10.1093/mnras/staa1381.

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ABSTRACT In this paper, we provide updated constraints on the bolometric quasar luminosity function (QLF) from z = 0 to z = 7. The constraints are based on an observational compilation that includes observations in the rest-frame IR, B band, UV, soft, and hard X-ray in past decades. Our method follows Hopkins et al. with an updated quasar SED model and bolometric and extinction corrections. The new best-fitting bolometric quasar luminosity function behaves qualitatively different from the old Hopkins model at high redshift. Compared with the old model, the number density normalization decreases towards higher redshift and the bright-end slope is steeper at z ≳ 2. Due to the paucity of measurements at the faint end, the faint end slope at z ≳ 5 is quite uncertain. We present two models, one featuring a progressively steeper faint-end slope at higher redshift and the other featuring a shallow faint-end slope at z ≳ 5. Further multiband observations of the faint-end QLF are needed to distinguish between these models. The evolutionary pattern of the bolometric QLF can be interpreted as an early phase likely dominated by the hierarchical assembly of structures and a late phase likely dominated by the quenching of galaxies. We explore the implications of this model on the ionizing photon production by quasars, the CXB spectrum, the SMBH mass density, and mass functions. The predicted hydrogen photoionization rate contributed by quasars is subdominant during the epoch of reionization and only becomes important at z ≲ 3. The predicted CXB spectrum, cosmic SMBH mass density, and SMBH mass function are generally consistent with existing observations.

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Meyer, Romain A., Roberto Decarli, Fabian Walter, Qiong Li, Ran Wang, Chiara Mazzucchelli, Eduardo Bañados, Emanuele P. Farina, and Bram Venemans. "Constraining Galaxy Overdensities around Three z ∼ 6.5 Quasars with ALMA and MUSE." Astrophysical Journal 927, no. 2 (March 1, 2022): 141. http://dx.doi.org/10.3847/1538-4357/ac4f67.

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Abstract We quantify galaxy overdensities around three high-redshift quasars with known [C ii]158 μm companions: PJ231–20 (z = 6.59), PJ308–21 (z = 6.24), and J0305–3150 (z = 6.61). Recent SCUBA2 imaging revealed the presence of 17 submillimeter galaxies (SMGs) with sky separations 0.′7 < θ < 2.′4 from these three quasars. We present ALMA Band 6 follow-up observations of these SCUBA2-selected SMGs to confirm their nature and redshift. We also search for continuum-undetected [C ii]158 μm emitters in the ALMA pointings and make use of archival MUSE observations to search for Lyα emitters (LAEs) associated with the quasars. While most of the SCUBA2-selected sources are detected with ALMA in the continuum, no [C ii]158 μm line emission could be detected, indicating that they are not at the quasar redshifts. Based on the serendipitous detection of CO 7–6 and [C i]809 μm emission lines, we find that four SMGs in the field of PJ231–20 are at z ∼ 2.4, which is coincident with the redshift of an Mg ii absorber in the quasar rest-frame UV spectrum. We report the discovery of two LAEs within <0.6 cMpc of PJ231–20 at the same redshift, indicating an LAE overdensity around this quasar. Taken together, these observations provide new constraints on the large-scale excess of Lyα- and [C ii]158 μm-emitting galaxies around z > 6 quasars and suggest that only wide-field observations, such as MUSE, ALMA, or JWST mosaics, can reveal a comprehensive picture of large-scale structure around quasars in the first billion years of the universe.

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Singal, J., S. Mutchnick, and V. Petrosian. "The X-Ray Luminosity Function Evolution of Quasars and the Correlation between the X-Ray and Ultraviolet Luminosities." Astrophysical Journal 932, no. 2 (June 1, 2022): 111. http://dx.doi.org/10.3847/1538-4357/ac6f06.

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Abstract We explore the evolution of the X-ray luminosity function of quasars and the intrinsic correlation between the X-ray and 2500 Å ultraviolet luminosities, utilizing techniques verified in previous works and a sample of over 4000 quasars detected with Chandra and XMM-Newton in the range 0 < z < 5. We find that quasars have undergone significantly less evolution with redshift in their total X-ray luminosity than in other wave bands. We then determine that the best-fit intrinsic power-law correlation between the X-ray and ultraviolet luminosities, of the form L X ′ ∝ ( L UV ′ ) γ , is γ = 0.28 ± 0.03, and we derive the luminosity function and density evolution in the X-ray band. We discuss the implications of these results for models of quasar systems.

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Jalan, Priyanka, Hum Chand, and Raghunathan Srianand. "Constraining the ratio of median pixel optical depth profile around z ∼ 4 quasars using the longitudinal proximity effect." Monthly Notices of the Royal Astronomical Society 505, no. 1 (May 10, 2021): 689–701. http://dx.doi.org/10.1093/mnras/stab1303.

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ABSTRACT We present a detailed study of the longitudinal proximity effect using a sample of 85 quasars spanning an emission redshift range of 3.5 ≤ zem ≤ 4.5 and Lyman continuum luminosity (L912) ranging from 1.06 × 1031 to 2.24 × 1032 erg s−1 Hz−1. We use the high-quality spectra of these quasars obtained at a spectral resolution of R ∼ 5100 and S/N ∼ 30 using X-SHOOTER spectrograph mounted on the Very Large Telescope (VLT). In our analysis, we compared the transmitted flux and pixel optical depth of the Ly α absorption originating from the vicinity of quasars to those from the general intergalactic medium (IGM) by using a redshift-matched control sample. The longitudinal proximity effect is found up to r ≤ 12 Mpc (proper) from quasars. By appropriately scaling up the pixel optical depth in the vicinity of quasars to account for the excess ionization by quasars, we constrain the ratio of median H i optical depth in the vicinity of the quasar to that of the IGM (Rτ(r)). The Rτ(r) is found to be significantly higher than unity up to 6 Mpc from the quasar with a typical radial profile of the form Rτ(r) = 1 + A × exp(− r/r0) with A = 9.16 ± 0.68 and r0 = 1.27 ± 0.08 Mpc. The integrated value of the scaled pixel optical depth over the radial bin of 0–6 Mpc is found to be higher by a factor of 2.55 ± 0.17 than the corresponding integrated value of the median pixel optical depth of the IGM. We also found Rτ(r) to be luminosity dependent.

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Gupta, N., G. Shukla, R. Srianand, J. K. Krogager, P. Noterdaeme, A. J. Baker, F. Combes, et al. "MALS SALT-NOT Survey of MIR-selected Powerful Radio-bright AGN at 0 < z < 3.5." Astrophysical Journal 929, no. 1 (April 1, 2022): 108. http://dx.doi.org/10.3847/1538-4357/ac4220.

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Abstract We present results of an optical spectroscopic survey using SALT and the Nordic Optical Telescope to build a Wide-field Infrared Survey Explorer mid-infrared color-based, dust-unbiased sample of powerful radio-bright (>200 mJy at 1.4 GHz) active galactic nuclei (AGN) for the MeerKAT Absorption Line Survey (MALS). Our sample has 250 AGN (median z = 1.8) showing emission lines, 26 with no emission lines, and 27 without optical counterparts. Overall, our sample is fainter (Δi = 0.6 mag) and redder (Δ(g−i) = 0.2 mag) than radio-selected quasars, and representative of fainter quasar population detected in optical surveys. About 20% of the sources are narrow-line AGN (NLAGN)–65% of these, at z < 0.5 are galaxies without strong nuclear emission, and 10% at z > 1.9, have emission line ratios similar to radio galaxies. The farthest NLAGN in our sample is M1513-2524 (z em = 3.132), and the largest radio source (size ∼330 kpc) is M0909-3133 (z em = 0.884). We discuss in detail 110 AGN at 1.9 < z < 3.5. Despite representing the radio loudest quasars (median R = 3685), their Eddington ratios are similar to the Sloan Digital Sky Survey quasars having lower R. We detect four C iv broad-absorption line (BAL) QSOs, all among AGN with least R, and highest black hole masses and Eddington ratios. The BAL detection rate ( 4 − 2 + 3 %) is consistent with that seen in extremely powerful (L 1.4GHz > 1025 W Hz−1) quasars. Using optical light curves, radio polarization, and γ-ray detections, we identify seven high-probability BL Lacertae objects. We also summarize the full MALS footprint to search for H i 21 cm and OH 18 cm lines at z < 2.

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Li, Jiang-Tao, Feige Wang, Jinyi Yang, Joel N. Bregman, Xiaohui Fan, and Yuchen Zhang. "A Chandra survey of z ≥ 4.5 quasars." Monthly Notices of the Royal Astronomical Society 504, no. 2 (April 15, 2021): 2767–82. http://dx.doi.org/10.1093/mnras/stab1042.

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ABSTRACT X-ray observations provide a unique probe of the accretion disc corona of supermassive black holes (SMBHs). In this paper, we present a uniform Chandra X-ray data analysis of a sample of 152 z ≥ 4.5 quasars. We firmly detect 46 quasars of this sample in 0.5–2 keV above 3σ and calculate the upper limits of the X-ray flux of the remaining. We also estimate the power-law photon index of the X-ray spectrum of 31 quasars. 24 of our sample quasars are detected in the FIRST or NVSS radio surveys; all of them are radio-loud. We statistically compare the X-ray properties of our z ≥ 4.5 quasars to other X-ray samples of active galactic nuclei (AGNs) at different redshifts. The relation between the rest-frame X-ray luminosity and other quasar parameters, such as the bolometric luminosity, UV luminosity, or SMBH mass, shows large scatters. These large scatters can be attributed to the narrow luminosity range at the highest redshift, the large measurement error based on relatively poor X-ray data, and the inclusion of radio-loud quasars in the sample. The LX–LUV relationship is significantly sublinear. We do not find a significant redshift evolution of the LX–LUV relation, expressed either in the slope of this relation, or the departure of individual AGNs from the best-fitting αOX–LUV relation (ΔαOX). The median value of the X-ray photon index is Γ ≈ 1.79, which does not show redshift evolution from z = 0 to z ∼ 7. The X-ray and UV properties of the most distant quasars could potentially be used as a standard candle to constrain cosmological models. The large scatter of our sample on the Hubble diagram highlights the importance of future large unbiased deep X-ray and radio surveys in using quasars in cosmological studies.

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Rector, Travis A., John Stocke, and Erica Ellingson. "Quasar Radio Morphology and Environment at z ≃ 1/2." Symposium - International Astronomical Union 175 (1996): 327–28. http://dx.doi.org/10.1017/s0074180900080979.

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The radio morphology of thirty radio-loud quasars atz≃ 1/2 is studied as a function of cluster galaxy density using data available in the literature. While correlations between several morphological parameters of the radio emission are consistent with interactions with an intracluster medium (ICM), we do not see the correlation between galaxy density and quasar radio morphology expected from ICM interaction. Therefore, distorted radio morphology isnotan indicator for the presence of a distant cluster as previously suggested. Because such correlations are found atz≃ 0, these results are suggestive that the rich clusters containing quasars atz≃ 1/2 have not yet developed a dense ICM. An inelastic collision with neighboring galaxies and intergalactic clouds can account for the morphology of several of the sources in this sample and is a viable alternative explanation.

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Lupi, Alessandro, Marta Volonteri, Roberto Decarli, Stefano Bovino, Joseph Silk, and Jacqueline Bergeron. "High-redshift quasars and their host galaxies – I. Kinematical and dynamical properties and their tracers." Monthly Notices of the Royal Astronomical Society 488, no. 3 (July 26, 2019): 4004–22. http://dx.doi.org/10.1093/mnras/stz1959.

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ABSTRACT Observations of high-redshift quasars provide information on the massive black holes (MBHs) powering them and the galaxies hosting them. Current observations of z ≳ 6 hosts, at sub-millimetre wavelengths, trace the properties of cold gas, and these are used to compare with the correlations between MBHs and galaxies characterizing the z = 0 population. The relations at z = 0, however, rely on stellar-based tracers of the galaxy properties. We perform a very high resolution cosmological zoom-in simulation of a z = 7 quasar including state-of-the-art non-equilibrium chemistry, MBH formation, growth, and feedback, to assess the evolution of the galaxy host and the central MBH, and compare the results with recent ALMA observations of high-redshift quasars. We measure both the stellar-based quantities used to establish the z = 0 correlations, as well as the gas-based quantities available in z ≳ 6 observations, adopting the same assumptions and techniques used in observational studies. The high-redshift studies argued that MBHs at high redshift deviate from the local MBH–galaxy correlations. In our analysis of the single galaxy we evolve, we find that the high-redshift population sits on the same correlations as the local one, when using the same tracers used at z = 0. When using the gas-based tracers, however, MBHs appear to be overmassive. The discrepancy between local and high-redshift MBHs seems to be caused by the different tracers employed, and the necessary assumptions, and not by an intrinsic difference. Better calibration of the tracers, higher resolution data, and availability of facilities that can probe the stellar population will be crucial to assess precisely and accurately high-redshift quasar hosts.

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Faisst, Andreas L., Ranga Ram Chary, Sergio Fajardo-Acosta, Roberta Paladini, Benjamin Rusholme, Nathaniel Stickley, George Helou, et al. "Joint Survey Processing. I. Compact Oddballs in the COSMOS Field—Low-luminosity Quasars at z > 6?" Astrophysical Journal 929, no. 1 (April 1, 2022): 66. http://dx.doi.org/10.3847/1538-4357/ac59b3.

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Abstract The faint-end slope of the quasar luminosity function at z ∼ 6 and its implication on the role of quasars in reionizing the intergalactic medium at early times has been an outstanding problem for some time. The identification of faint high-redshift quasars with luminosities of <1044.5 erg s−1 is challenging. They are rare (few per square degree), and the separation of these unresolved quasars from late-type stars and compact star-forming galaxies is difficult from ground-based observations alone. In addition, source confusion becomes significant at >25 mag, with ∼30% of sources having their flux contaminated by foreground objects when the seeing resolution is ∼0″.7. We mitigate these issues by performing a pixel-level joint processing of ground and space-based data from Subaru/Hyper-SuprimeCam (HSC) and Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). We create a deconfused catalog over the 1.64 deg2 of the COSMOS field, after accounting for spatial varying point-spread functions and astrometric differences between the two data sets. We identify twelve low-luminosity (M UV ∼ −21 mag) z > 6 quasar candidates through (i) their red color measured between ACS/F814W and HSC/i band and (ii) their compactness in the space-based data. Nondetections of our candidates in Hubble DASH data argues against contamination from late-type stars. Our constraints on the faint end of the quasar luminosity function at z ∼ 6.4 suggest a negligibly small contribution to reionization compared to the star-forming galaxy population. The confirmation of our candidates and the evolution of number density with redshift could provide better insights into how supermassive galaxies grew in the first billion years of cosmic time.

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Brosche, P., C. Ducourant, R. Galas, M. Geffert, and A. Karafistan. "Quasar Link Conditions for Hipparcos." International Astronomical Union Colloquium 127 (1991): 215. http://dx.doi.org/10.1017/s0252921100063806.

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AbstractFictitious proper motioms of quasars and of their surrounding stars have been determined based on plates with an epoch difference of up to 90 years. From the fact that the true proper motions of the quasar are vanishingly small, we obtain conditions for the extragalactic calibration of the preliminary Hipparcos system. We present results for the fields of 3C 273, OQ 208, 3C 371 and 3C 390.3. With the data it is possible to achieve the link with random errors smaller than 0₺ 15 per century.

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Habouzit, Mélanie, Masafusa Onoue, Eduardo Bañados, Marcel Neeleman, Daniel Anglés-Alcázar, Fabian Walter, Annalisa Pillepich, Romeel Davé, Knud Jahnke, and Yohan Dubois. "Co-evolution of massive black holes and their host galaxies at high redshift: discrepancies from six cosmological simulations and the key role of JWST." Monthly Notices of the Royal Astronomical Society 511, no. 3 (January 31, 2022): 3751–67. http://dx.doi.org/10.1093/mnras/stac225.

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ABSTRACT The James Webb Space Telescope will have the power to characterize high-redshift quasars at z ≥ 6 with an unprecedented depth and spatial resolution. While the brightest quasars at such redshift (i.e. with bolometric luminosity $L_{\rm bol}\geqslant 10^{46}\, \rm erg/s$) provide us with key information on the most extreme objects in the Universe, measuring the black hole (BH) mass and Eddington ratios of fainter quasars with $L_{\rm bol}= 10^{45}-10^{46}\, \rm erg\,s^{ -1}$ opens a path to understand the build-up of more normal BHs at z ≥ 6. In this paper, we show that the Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA large-scale cosmological simulations do not agree on whether BHs at z ≥ 4 are overmassive or undermassive at fixed galaxy stellar mass with respect to the MBH − M⋆ scaling relation at z = 0 (BH mass offsets). Our conclusions are unchanged when using the local scaling relation produced by each simulation or empirical relations. We find that the BH mass offsets of the simulated faint quasar population at z ≥ 4, unlike those of bright quasars, represent the BH mass offsets of the entire BH population, for all the simulations. Thus, a population of faint quasars with $L_{\rm bol}= 10^{45}-10^{46}\, \rm erg\,s^{ -1}$ observed by JWST can provide key constraints on the assembly of BHs at high redshift. Moreover, this will help constraining the high-redshift regime of cosmological simulations, including BH seeding, early growth, and co-evolution with the host galaxies. Our results also motivate the need for simulations of larger cosmological volumes down to z ∼ 6, with the same diversity of subgrid physics, in order to gain statistics on the most extreme objects at high redshift.

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Marziani, P., A. del Olmo, M. A. Martínez-Carballo, M. L. Martínez-Aldama, G. M. Stirpe, C. A. Negrete, D. Dultzin, M. D’Onofrio, E. Bon, and N. Bon. "Black hole mass estimates in quasars." Astronomy & Astrophysics 627 (July 2019): A88. http://dx.doi.org/10.1051/0004-6361/201935265.

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Context. The inter-line comparison between high- and low-ionization emission lines has yielded a wealth of information on the structure and dynamics of the quasar broad line region (BLR), including perhaps the earliest unambiguous evidence in favor of a disk + wind structure in radio-quiet quasars. Aims. We carried out an analysis of the C IVλ1549 and Hβ line profiles of 28 Hamburg-ESO high-luminosity quasars and of 48 low-z, low-luminosity sources in order to test whether the width of the high-ionization line C IVλ1549 could be correlated with Hβ and be used as a virial broadening estimator. Methods. We analyze intermediate- to high-S/N, moderate-resolution optical and near-infrared (NIR) spectra covering the redshifted C IVλ1549 and Hβ over a broad range of luminosity log L ∼ 44 − 48.5 [erg s−1] and redshift (0 − 3), following an approach based on the quasar main sequence. Results. The present analysis indicates that the line width of C IVλ1549 is not immediately offering a virial broadening estimator equivalent to Hβ. At the same time a virialized part of the BLR appears to be preserved even at the highest luminosities. We suggest a correction to FWHM(C IVλ1549) for Eddington ratio (using the C IVλ1549 blueshift as a proxy) and luminosity effects that can be applied over more than four dex in luminosity. Conclusions. Great care should be used in estimating high-L black hole masses MBH from C IVλ1549 line width. However, once a corrected FWHM C IVλ1549 is used, a C IVλ1549-based scaling law can yield unbiased MBH values with respect to the ones based on Hβ with sample standard deviation ≈0.3 dex.

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Marziani, Paola, Ascensión del Olmo, C. Alenka Negrete, Deborah Dultzin, Enrico Piconcelli, Giustina Vietri, Mary Loli Martínez-Aldama, et al. "The Intermediate-ionization Lines as Virial Broadening Estimators for Population A Quasars*." Astrophysical Journal Supplement Series 261, no. 2 (July 27, 2022): 30. http://dx.doi.org/10.3847/1538-4365/ac6fd6.

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Abstract The identification of a virial broadening estimator in the quasar UV rest frame suitable for black hole mass computation at high redshift has become an important issue. We compare the H i Balmer H β line width to the ones of two intermediate-ionization lines: the Al iii λ1860 doublet and the C iii] λ1909 line, over a wide interval of redshift and luminosity (0 ≲ z ≲ 3.5; 43 ≲ log L ≲ 48.5 [erg s−1]), for 48 sources belonging to the quasar population characterized by intermediate to high values of the Eddington ratio (Population A). The present analysis indicates that the line widths of Al iii λ1860 and H β are highly correlated and can be considered equivalent for most Population A quasars over five orders of magnitude in luminosity; for C iii] λ1909, multiplication by a constant correction factor ξ ≈ 1.25 is sufficient to bring the FWHM of C iii] in agreement with that of H β. The statistical concordance between low-ionization and intermediate-ionization lines suggests that they predominantly arise from the same virialized part of the broad-line region. However, blueshifts of modest amplitude (few hundred kilometers per second) with respect to the quasar rest frame and an excess (≲1.1) Al iii broadening with respect to H β are found in a fraction of our sample. Scaling laws to estimate M BH of high-redshift quasars using the Al iii and C iii] line widths have rms scatter ≈0.3 dex. The Al iii scaling law takes the form log M BH ≈ 0.58 log L 1700,44 + 2 logFWHM + 0.49 [M ⊙].

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Brunner, H., T. Dörrer, P. Friedrich, G. Lamer, and R. Staubert. "ROSAT Observations of an Optical Quasar Survey Field." Symposium - International Astronomical Union 159 (1994): 368. http://dx.doi.org/10.1017/s0074180900175618.

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Deep (T∼35 ksec) pointed ROSAT observations of a 2.2° × 2.2° optical quasar survey field (149 quasars; mlim = 20.5; Crampton et al., 1989) have yielded a detection rate (3 σ) of ∼ 60 % (86 quasars; limiting sensitivity ∼ 5 · 10−15 erg cm−2 s−1 keV−1 at 1 keV). See Fig. 1 for the distribution of the ROSAT PSPC source count rates and Fig. 2a, b for the fraction of quasars detected in X-rays as a function of redshift and optical magnitude. 46 quasars were bright enough to perform spectral power law fits. The mean energy power law index drops from ∼ 1.4 at z = 0 to ∼ 0.9 at z > 2 (Fig. 4; only the 20 brightest sources are plotted). This is interpreted as being due to a break in the spectrum between a soft, thermal accretion disk and a hard power law component, occuring at a source frame energy around 1 keV (Fig. 5). Mean accretion disk model parameters are derived (M = 5.108 M⊙, Ṁ = 0.65 MEdd., αvisc. = 0.5) using an optically thin α-accretion disk model (Dörrer et al., 1992 and references therein). Model predictions for the decline of the X-ray spectral index with redshift are plotted in Fig. 4. The αox distribution (Fig. 3; dotted line: X-ray upper limits) and the optical number-redshift relation (Fig. 6; dotted line: X-ray number-redshift relation) is modeled using the accretion disk parameters as determined from the X-ray spectral data and assuming a constant comoving volume density (H0 = 100 km/s Mpc, q0 = 0.5) and statistical orientation of the inclination angles of the model source population.

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Combes, F., N. Gupta, G. I. G. Jozsa, and E. Momjian. "Discovery of CO absorption at z = 0.05 in G0248+430." Astronomy & Astrophysics 623 (March 2019): A133. http://dx.doi.org/10.1051/0004-6361/201935057.

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Absorption lines in front of distant quasars are quite rare in the millimeter domain. They can, however, bring very useful and complementary information to emission lines. We report here the detection with NOEMA of CO(1–0) and CN(1–0) lines in absorption, and the confirmation of CO emission in the quasar/galaxy pair Q0248+430/G0248+430. The system G0248+430 corresponds to two merging galaxies (a Seyfert and a LINER) at z = 0.0519 with a tidal tail just on the line of sight to the background quasar Q0248+430 at z = 1.313. Optical (CaII, NaI), H I 21 cm, and OH-1667 MHz absorption lines associated with the tidal tail of the foreground system have previously been detected toward the quasar, while four CO lines at different rotation J levels have been detected in emission from the foreground galaxies. New H I 21 cm line observations with the upgraded GMRT array are also presented. We discuss the molecular content of the merging galaxies, and the physical conditions in the absorbing interstellar medium of the tidal tail.

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Chen, Pei-sheng, Hong-guang Shan, Pin Zhang, and Yi-fei Gao. "2Mass Observation Of Infrared Quasars." Astrophysics and Space Science 302, no. 1-4 (April 29, 2006): 17–25. http://dx.doi.org/10.1007/s10509-005-9000-0.

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Choi, Hyunseop, Karen M. Leighly, Donald M. Terndrup, Collin Dabbieri, Sarah C. Gallagher, and Gordon T. Richards. "The Physical Properties of Low-redshift FeLoBAL Quasars. I. Spectral-synthesis Analysis of the Broad Absorption-line (BAL) Outflows Using SimBAL." Astrophysical Journal 937, no. 2 (September 29, 2022): 74. http://dx.doi.org/10.3847/1538-4357/ac61d9.

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Abstract We present the first systematic study of 50 low-redshift (0.66 < z < 1.63) iron low-ionization broad absorption-line quasars (FeLoBALQs) using SimBAL, which represents a more than five-fold increase in the number of FeLoBALQs with detailed absorption line spectral analyses. We found the outflows have a wide range of ionization parameters, − 4 ≲ log U ≲ 1.2 and densities, 2.8 ≲ log n ≲ 8 [ cm − 3 ] . The objects in our sample showed FeLoBAL gas located at a wide range of distances 0 ≲ log R ≲ 4.4 [pc], although we do not find any evidence for disk winds (with R ≪ 0.01 pc) in our sample. The outflow strength primarily depends on the outflow velocity with faster outflows found in quasars that are luminous or that have flat or redder spectral energy distributions. We found that ∼18% of the FeLoBALQs in the sample have the significantly powerful outflows needed for quasar feedback. Eight objects showed overlapping troughs in the spectra, and we identified eleven loitering outflow objects, a new class of FeLoBALQs that are characterized by low outflow velocities and high column density winds located log R ≲ 1 [pc] from the central engine. The FeLoBALs in loitering outflows objects do not show properties expected for radiatively driven winds, and these objects may represent a distinct population among FeLoBALQs. We discuss how the potential acceleration mechanisms and the origins of the FeLoBAL winds may differ for outflows at different locations in quasars.

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23

Zhu, Xing-fen. "On the alignment of quasars." Chinese Astronomy and Astrophysics 10, no. 2 (June 1986): 94–97. http://dx.doi.org/10.1016/0275-1062(86)90033-0.

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Kotilainen, J. K., R. Decarli, R. Falomo, A. Treves, M. Labita, and R. Scarpa. "Co-Evolution of Supermassive Black Holes and Their Host Galaxies." Proceedings of the International Astronomical Union 5, S267 (August 2009): 34–39. http://dx.doi.org/10.1017/s1743921310005533.

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AbstractWe study the evolution of the MBH/Mhost relation up to z = 3 for a sample of 96 quasars with known host galaxy luminosities. Black hole masses are estimated assuming virial equilibrium in the broad-line regions, while the host galaxy masses are inferred from their luminosities. With this data, we are able to pin down the evolution of the MBH/Mhost relation over 85% of the age of the universe. While the MBH/Lhost relation remains nearly unchanged, taking into account the aging of the stellar population, we find that the MBH/Mhost ratio (Γ) increases by a factor ~ 7 from z = 0 to z = 3. We show that the evolution of Γ is independent of radio loudness and quasar luminosity. We propose that the most massive black holes, in their quasar phase at high-redshift, become extremely rare objects in host galaxies of similar mass in the local universe.

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O'Dea, C. P., R. Barvainis, and P. Challis. "High resolution VLA observations of core-dominated quasars." Symposium - International Astronomical Union 119 (1986): 217–18. http://dx.doi.org/10.1017/s0074180900152726.

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We selected 16 core-dominated sources based on two criteria. (1) They have a core-jet VLBI morphology. (2) Previous observations at lower resolution indicated that there was extended structure on scales of ≥1″. The sources were observed in the A configuration of the VLA at 6 and 2 cm with typical resolutions of ∼0.″45 and ∼0.″15 respectively. Contour plots of total intensity with E vectors superposed (length proportional to fractional polarization) of four sources with jets are shown in Figure 1.

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Ubachukwu, A. "A Constraint on the Standard Beaming Model for Superluminal Sources." Publications of the Astronomical Society of Australia 16, no. 2 (1999): 130–33. http://dx.doi.org/10.1071/as99130.

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AbstractWe have used two subsamples of superluminal quasars to test the relativistic beaming model, and to place useful constraints on the radio source orientation hypothesis and cosmology. Based on the variation of the observed ratio R of the core-to-lobe radio luminosities with proper motion μ for the subsample of lobe-selected quasars, we show that the observed R–μ data can be explained in terms of a bulk relativistic motion with Lorentz factor γ≈4. Also, from the observed proper motion versus redshift (μ–z) plot for this subsample, we show that γ≈4 implies a high density universe with deceleration parameter q0 = 0·5. Furthermore, from the observed (μ–z) plot for the two subsamples taken separately, we show that both γ and μ for the core-selected subsample exceed those of the lobe-selected subsample by a factor of 2 for the q0 = 0·5 world model. This result is demonstrated to be consistent with an orientation-based unified scheme in which lobe-selected quasars lie, on the average, at an angle which is a factor of ∼2–3 larger than that of their core-selected counterparts.

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Bischetti, M., C. Feruglio, E. Piconcelli, F. Duras, M. Pérez-Torres, R. Herrero, G. Venturi, et al. "The WISSH quasars project." Astronomy & Astrophysics 645 (December 24, 2020): A33. http://dx.doi.org/10.1051/0004-6361/202039057.

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Context. Sources at the brightest end of the quasi-stellar object (QSO) luminosity function, during the peak epoch in the history of star formation and black hole accretion (z ∼ 2−4, often referred to as “Cosmic noon”) are privileged sites to study the cycle of feeding & feedback processes in massive galaxies. Aims. We aim to perform the first systematic study of cold gas properties in the most luminous QSOs, by characterising their host-galaxies and environment. These targets exhibit indeed widespread evidence of outflows at nuclear and galactic scales. Methods. We analyse ALMA, NOEMA and JVLA observations of the far-infrared continuum, CO and [CII] emission lines in eight QSOs (bolometric luminosity LBol ≳ 3 × 1047 erg s−1) from the WISE-SDSS selected hyper-luminous (WISSH) QSOs sample at z ∼ 2.4−4.7. Results. We report a 100% emission line detection rate and a 80% detection rate in continuum emission, and we find CO emission to be consistent with the steepest CO ladders observed so far. Sub-millimetre data reveal presence of (one or more) bright companion galaxies around ∼80% of WISSH QSOs, at projected distances of ∼6−130 kpc. We observe a variety of sizes for the molecular gas reservoirs (∼1.7−10 kpc), mostly associated with rotating disks with disturbed kinematics. WISSH QSOs typically show lower CO luminosity and higher star formation efficiency than infrared matched, z ∼ 0−3 main-sequence galaxies, implying that, given the observed SFR ∼170−1100 M⊙ yr−1, molecular gas is converted into stars in ≲50 Myr. Most targets show extreme dynamical to black-hole mass ratios Mdyn/MBH ∼ 3−10, two orders of magnitude smaller than local relations. The molecular gas fraction in the host-galaxies of WISSH is lower by a factor of ∼10−100 than in star forming galaxies with similar M*. Conclusions. Our analysis reveals that hyper-luminous QSOs at Cosmic noon undergo an intense growth phase of both the central super-massive black hole and of the host-galaxy. These systems pinpoint the high-density sites where giant galaxies assemble, where we show that mergers play a major role in the build-up of the final host-galaxy mass. We suggest that the observed low molecular gas fraction and short depletion timescale are due to AGN feedback, whose presence is indicated by fast AGN-driven ionised outflows in all our targets.

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Rawlings, S. "Cosmological Studies from Radio Source Samples." Symposium - International Astronomical Union 199 (2002): 34–49. http://dx.doi.org/10.1017/s0074180900168512.

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I review some recent cosmological studies based on redshift surveys of radio sources selected at low frequencies. The accretion rate onto the central black hole is identified as the basis of a crude physical division of the low-frequency population into two sub-populations: the first comprises ‘Eddington-tuned’ (high accretion rate) quasars and their torus-hidden counterparts; the second comprises ‘starved quasars’ like M87. There exist remarkable similarities between the shapes and evolutionary behaviours of the luminosity functions of radio sources and radio-quiet quasars; all luminous AGN are ∼ 300—times rarer at epochs corresponding to z ∼ 0 than at z ∼ 2.5. I argue that any evidence that quasars were intrinsically rarer at z ∼ 5 than at z ∼ 2.5 is as yet both tentative and indirect. A simple calculation suggests that the radio source population has been over-looked as a potentially important contributor to the entropy budget of the Universe. A recent sub-mm survey of radio sources is used to demonstrate a connection between the events which trigger jets and intense bursts of star formation, and a close link between the histories of star formation and AGN activity is proposed. I discuss the aims and methods of future large redshift surveys of radio sources, emphasising the importance of dovetailing these with the development of robust physical models for radio sources and their epoch-dependent environments.

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Kuźmicz, Agnieszka, Arti Goyal, Stanisław Zola, Marek Jamrozy, Marek Dróżdż, Waldemar Ogłoza, Michał Siwak, Daniel E. Reichart, Vladimir V. Kouprianov, and Daniel B. Caton. "Optical Variability of Eight FRII-type Quasars with 13 yr Photometric Light Curves." Astrophysical Journal Supplement Series 263, no. 1 (November 1, 2022): 16. http://dx.doi.org/10.3847/1538-4365/ac9622.

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Abstract We characterize the optical variability properties of eight lobe-dominated radio quasars (QSOs): B2 0709+37, FBQS J095206.3+235245, PG 1004+130, [HB89] 1156+631, [HB89] 1425+267, [HB89] 1503+691, [HB89] 1721+343, and 4C +74.26, systematically monitored for a duration of 13 yr since 2009. The quasars are radio-loud objects with extended radio lobes that indicate their orientation close to the sky plane. Five of the eight QSOs are classified as giant radio quasars. All quasars showed variability during our monitoring, with magnitude variations between 0.3 and 1 mag for the least variable and the most variable QSOs, respectively. We performed both structure function (SF) analysis and power spectral density (PSD) analysis for the variability characterization and search for characteristic timescales and periodicities. As a result of our analysis, we obtained relatively steep SF slopes (α ranging from 0.49 to 0.75) that are consistent with the derived PSD slopes (∼2–3). All the PSDs show a good fit to single power-law forms, indicating a red-noise character of variability between timescales of ∼13 yr and weeks. We did not measure reliable characteristic timescales of variability from the SF analysis, which indicates that the duration of the gathered data is too short to reveal them. The absence of bends in the PSDs (change of slope from ≥1 to ∼0) on longer timescales indicates that optical variations are most likely caused by thermal instabilities in the accretion disk.

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Williams, Liliya L. R., and Prasenjit Saha. "Pixelated Lenses and [ITAL]H[/ITAL][TINF]0[/TINF] from Time-Delay Quasars." Astronomical Journal 119, no. 2 (February 2000): 439–50. http://dx.doi.org/10.1086/301234.

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Cegłowski, M., M. Kunert-Bajraszewska, and C. Roskowiński. "VLBI survey of compact broad absorption line quasars with balnicity index BI = 0." Monthly Notices of the Royal Astronomical Society 450, no. 1 (April 22, 2015): 1123–35. http://dx.doi.org/10.1093/mnras/stv560.

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Gurvits, L. I., S. Frey, R. T. Schilizzi, K. I. Kellermann, A. P. Lobanov, N. Kawaguchi, H. Kobayashi, Y. Murata, H. Hirabayashi, and I. I. K. Pauliny-Toth. "Dual-frequency VSOP observations of extremely high redshift quasars." Advances in Space Research 26, no. 4 (January 2000): 719–22. http://dx.doi.org/10.1016/s0273-1177(99)01199-0.

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Yan Ming, Cheng Fu-hua, and You Jun-han. "The 3000 a bump in quasars and Seyfert galaxies." Chinese Astronomy and Astrophysics 13, no. 3 (September 1989): 268–71. http://dx.doi.org/10.1016/0275-1062(89)90004-0.

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Peng, Chien Y. "What Do Statistics Reveal About the MBH–Mbulge Correlation and Co-Evolution?" Proceedings of the International Astronomical Union 5, S267 (August 2009): 161–71. http://dx.doi.org/10.1017/s1743921310006101.

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AbstractObservational data show that the correlation between the masses of supermassive black holes MBH and galaxy bulge masses Mbulge follows a nearly linear trend, and that the correlation is strongest with the bulge rather than the total stellar mass Mgal. With increasing redshift, the ratio Γ=MBH/Mbulge relative to z = 0 also seems to be larger for MBH≳108.5M⊙. This study looks more closely at statistics to see what effect it has on creating, and observing, the MBH–Mbulge correlation. It is possible to show that if galaxy merging statistics can drive the correlation, minor mergers are responsible for causing a convergence to linearity most evident at high masses, whereas major mergers have a central limit convergence that more strongly reduces the scatter. This statistical reasoning is agnostic about galaxy morphology. Therefore, combining statistical prediction (more major mergers ⟹ tighter correlation) with observations (bulges = tightest correlation), would lead one to conclude that more major mergers (throughout an entire merger tree, not just the primary branch) give rise to more prominent bulges. Lastly, with regard to controversial findings that Γ increases with redshift, this study shows why the luminosity function (LF) bias argument, taken correctly at face value, actually strengthens, rather than weakens, the findings. However, correcting for LF bias is unwarranted because the BH mass scale for quasars is bootstrapped to the MBH–σ* correlation in normal galaxies at z = 0, and quasar–quasar comparisons are mostly internally consistent. In Monte-Carlo simulations, high Γ galaxies are indeed present: they are statistical outliers (i.e., “under-merged”) that take longer to converge to linearity via minor mergers. Additional evidence that the galaxies are undermassive at z≳2 for their MBH is that the quasar hosts are very compact for their expected mass.

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Ridgway, S., T. Heckman, D. Calzetti, and M. Lehnert. "HST NICMOS imaging of z∼2–3 radio-quiet quasars." New Astronomy Reviews 46, no. 2-7 (May 2002): 175–80. http://dx.doi.org/10.1016/s1387-6473(01)00175-0.

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Fiore, Fabrizio, and Martin Elvis. "On the observational evidence for accreting black holes in quasars." Advances in Space Research 19, no. 1 (January 1997): 85–94. http://dx.doi.org/10.1016/s0273-1177(97)00041-0.

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Weisenbach, Luke, Paul L. Schechter, and Sahil Pontula. "“Worst-case” Microlensing in the Identification and Modeling of Lensed Quasars." Astrophysical Journal 922, no. 1 (November 1, 2021): 70. http://dx.doi.org/10.3847/1538-4357/ac2228.

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Abstract Although microlensing of macrolensed quasars and supernovae provides unique opportunities for several kinds of investigations, it can add unwanted and sometimes substantial noise. While microlensing flux anomalies may be safely ignored for some observations, they severely limit others. “Worst-case” estimates can inform the decision whether or not to undertake an extensive examination of microlensing scenarios. Here, we report “worst-case” microlensing uncertainties for point sources lensed by singular isothermal potentials, parameterized by a convergence equal to the shear and by the stellar fraction. The results can be straightforwardly applied to nonisothermal potentials by utilizing the mass sheet degeneracy. We use microlensing maps to compute the fluctuations in image micromagnifications and estimate the stellar fraction at which the fluctuations are greatest for a given convergence. We find that the worst-case fluctuations happen at the stellar fraction κ ⋆ = 1 ∣ μ macro ∣ . For macrominima, the fluctuations in both magnification and demagnification appear to be bounded (1.5 > Δm > −1.3, where Δm is the magnitude relative to the average macromagnification). Magnifications for macrosaddles are bounded as well (Δm > −1.7). In contrast, demagnifications for macrosaddles appear to have unbounded fluctuations as 1/μ macro → 0 and κ ⋆ → 0.

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FILLOUX, C., F. DURIER, J. A. F. PACHECO, and J. SILK. "EVOLUTION OF SUPERMASSIVE BLACK HOLES FROM COSMOLOGICAL SIMULATIONS." International Journal of Modern Physics D 19, no. 08n10 (August 2010): 1233–40. http://dx.doi.org/10.1142/s0218271810017603.

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The correlations between the mass of supermassive black holes and the properties of their host galaxies are investigated through cosmological simulations. Black holes grow from seeds of 100 M⊙ are inserted into density peaks presented in the redshift range 12–15. Seeds grow essentially by accreting matter from a nuclear disk and also by coalescences resulting from merger episodes. At z = 0, our simulations reproduce the black hole mass function and the correlations of the black hole mass, both with stellar velocity dispersion and host dark halo mass. Moreover, the evolution of the black hole mass density derived from the present simulations agrees with that derived from the bolometric luminosity of quasars, indicating that the average accretion history of seeds is adequately reproduced. However, our simulations are unable to form black holes with masses above 109 M⊙ at z ~ 6, whose existence is inferred from the bright quasars detected by the Sloan survey in this redshift range.

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Kunert-Bajraszewska, M., M. Cegłowski, K. Katarzyński, and C. Roskowiński. "A VLBI survey of compact broad absorption line quasars with balnicity index BI > 0." Astronomy & Astrophysics 579 (July 2015): A109. http://dx.doi.org/10.1051/0004-6361/201526091.

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Zwaan, Martin A., Marc A. W. Verheijen, and Frank H. Briggs. "HI Column Density Distribution Function at z = 0: Connection to Damped Lyα Statistics." Publications of the Astronomical Society of Australia 16, no. 1 (1999): 100–105. http://dx.doi.org/10.1071/as99100.

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AbstractWe present a measurement of the HI column density distribution function f(Nhi) at the present epoch for column densities > 1020 cm−2. These high column densities compare to those measured in damped Lyα lines seen in absorption against background quasars. Although observationally rare, it appears that the bulk of the neutral gas in the Universe is associated with these damped Lyα systems. In order to obtain a good anchor point at z = 0 we determine f(Nhi) in the local Universe by using 21 cm synthesis observations of a complete sample of spiral galaxies. We show that f(Nhi) for damped Lyα systems has changed significantly from high z to the present and that change is greatest for the highest column densities. The measurements indicate that low surface brightness galaxies make a minor contribution to the cross section for HI, especially for NHI > 1021 cm−2.

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Bargiacchi, G., G. Risaliti, M. Benetti, S. Capozziello, E. Lusso, A. Saccardi, and M. Signorini. "Cosmography by orthogonalized logarithmic polynomials." Astronomy & Astrophysics 649 (May 2021): A65. http://dx.doi.org/10.1051/0004-6361/202140386.

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Cosmography is a powerful tool for investigating the Universe kinematic and then for reconstructing the dynamics in a model-independent way. However, recent new measurements of supernovae Ia and quasars have populated the Hubble diagram up to high redshifts (z ∼ 7.5) and the application of the traditional cosmographic approach has become less straightforward due to the large redshifts implied. Here we investigate this issue through an expansion of the luminosity distance–redshift relation in terms of orthogonal logarithmic polynomials. In particular, we point out the advantages of a new procedure called orthogonalization, and we show that such an expansion provides a very good fit in the whole z = 0 ÷ 7.5 range to both real and mock data obtained assuming various cosmological models. Moreover, although the cosmographic series is tested well beyond its convergence radius, the parameters obtained expanding the luminosity distance–redshift relation for the Lambda cold dark matter (ΛCDM) model are broadly consistent with the results from a fit of mock data obtained with the same cosmological model. This provides a method for testing the reliability of a cosmographic function to study cosmological models at high redshifts, and it demonstrates that the logarithmic polynomial series can be used to test the consistency of the ΛCDM model with the current Hubble diagram of quasars and supernovae Ia. We confirm a strong tension (at > 4σ) between the concordance cosmological model and the Hubble diagram at z > 1.5. This tension is dominated by the contribution of quasars at z > 2 and also starts to be present in the few supernovae Ia observed at z > 1.

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Roukema, B. F., and G. A. Mamon. "Large Scale Structure Among z ∼ 2 Quasars as a Cosmological Standard Ruler." Symposium - International Astronomical Union 199 (2002): 54–55. http://dx.doi.org/10.1017/s0074180900168536.

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The peak in the power spectrum at ≈ 130h−1 Mpc at low redshifts provides a standard ruler in comoving space. This scale is shown to be present in the observed quasar distribution at z ∼ 2. This implies strong constraints on the density parameter, Ω0, and weaker constraints on the cosmological constant, λ0. Independently of λ0 (in the range λ0 ∊ [0, 1]), the constraint is 0.1 < Ω0 < 0.45 (68% confidence limit).Combination of the power spectrum peak method with very independent results from the supernovae Type Ia method yields Ω0 = (0.30 ± 0.11) + (0.57 ± 0.11)(λ0 −0.7), 0.55 < λ0 < 0.95, (68% confidence limits) without assuming Ω0 + λ0 = 1. This supports the almost flat, perturbed Friedmann-Lemaître-Robertson-Walker model, independently of any cosmic microwave background observations.

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Wang, Ding-xiong, and Xue-bing Wu. "On the correlation of black hole spin and radio jet radiation of quasars." Chinese Astronomy and Astrophysics 23, no. 3 (July 1999): 281–87. http://dx.doi.org/10.1016/s0275-1062(99)00057-0.

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Osmer, Patrick S., Alain C. Porter, and Richard F. Green. "Luminosity effects and the emission-line properties of quasars with 0 less than Z less than 3.8." Astrophysical Journal 436 (December 1994): 678. http://dx.doi.org/10.1086/174942.

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Farina, Emanuele Paolo, Jan-Torge Schindler, Fabian Walter, Eduardo Bañados, Frederick B. Davies, Roberto Decarli, Anna-Christina Eilers, et al. "The X–shooter/ALMA Sample of Quasars in the Epoch of Reionization. II. Black Hole Masses, Eddington Ratios, and the Formation of the First Quasars." Astrophysical Journal 941, no. 2 (December 1, 2022): 106. http://dx.doi.org/10.3847/1538-4357/ac9626.

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Abstract We present measurements of black hole masses and Eddington ratios (λ Edd) for a sample of 38 bright (M 1450 < −24.4 mag) quasars at 5.8 ≲ z ≲ 7.5, derived from Very Large Telescope/X–shooter near–IR spectroscopy of their broad C iv and Mg ii emission lines. The black hole masses (on average, M BH ∼ 4.6 × 109 M ⊙) and accretion rates (0.1 ≲ λ Edd ≲ 1.0) are broadly consistent with that of similarly luminous 0.3 ≲ z ≲ 2.3 quasars, but there is evidence for a mild increase in the Eddington ratio above z ≳ 6. Combined with deep Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C II] 158 μm line from the host galaxies and VLT/MUSE investigations of the extended Lyα halos, this study provides fundamental clues to models of the formation and growth of the first massive galaxies and black holes. Compared to local scaling relations, z ≳ 5.7 black holes appear to be over-massive relative to their hosts, with accretion properties that do not change with host galaxy morphologies. Assuming that the kinematics of the T ∼ 104 K gas, traced by the extended Lyα halos, are dominated by the gravitational potential of the dark matter halo, we observe a similar relation between black hole mass and circular velocity as reported for z ∼ 0 galaxies. These results paint a picture where the first supermassive black holes reside in massive halos at z ≳ 6 and lead the first stages of galaxy formation by rapidly growing in mass with a duty cycle of order unity. The duty cycle needs to drastically drop toward lower redshifts, while the host galaxies continue forming stars at a rate of hundreds of solar masses per year, sustained by the large reservoirs of cool gas surrounding them.

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Slee, OB, AD Bobra, D. Waldron, and J. Lim. "Radio Source Scintillations Through Comet Tails Revisited: Comet Wilson (1987)." Australian Journal of Physics 43, no. 6 (1990): 801. http://dx.doi.org/10.1071/ph900801.

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Observations of the quasars 0606-795 and 0637-752 as the tail of Comet Wilson swept across them on May 1 and May 2, 1987, showed a three-fold increase in scintillation index over that of nearby compact radio sources outside the tail. Two scintillation regimes have been identified: (1) small-scale turbulence of 10-40 km develops near the tail-axis; (2) large-scale turbulence of 90-350 km is present in the off-axis transition region between the tail plasma and solar wind. At a distance 0�12 AU downstream from the nucleus the r.m.s. electron-density variation in these turbules is 4-8 cm-3 on axis and 0�8-1� 7 cm-3 in the transition region between the tail and the solar wind. The reported negative results from earlier comets are shown to be of doubtful significance.

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Riechers, D. A., F. Walter, C. L. Carilli, K. K. Knudsen, K. Y. Lo, D. J. Benford, J. G. Staguhn, et al. "Detecting Low-Order CO Emission from z ≳ 4 Quasar Host Galaxies." Proceedings of the International Astronomical Union 2, S235 (August 2006): 423. http://dx.doi.org/10.1017/s1743921306010507.

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AbstractMolecular gas has now been detected in 15 z>2 QSOs. These detections are commonly obtained by observing high–J CO transitions due to their relatively high peak fluxes and observing frequencies in the millimeter atmospheric windows. However, only observations of the CO ground-state transition, CO(1–0), have the potential to trace the molecular gas at lower excitations, which may give a better estimate of the total molecular gas mass of high–z QSOs. Here we present first z>4 CO(1–0) observations obtained with the NRAO Green Bank Telescope and the MPIfR Effelsberg telescope (Riechers et al. 2006). With these two 100m telescopes, we detect the CO(1–0) transition in the high–redshift QSOs BR 1202-0725 (z = 4.7), PSS J2322+1944 (z = 4.1), and APM 08279+5255 (z = 3.9). We find that the CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies. Utilizing large velocity gradient (LVG) models based on previous results for higher–J CO transitions, we derive that all CO emission can be described by a single gas component and that all molecular gas appears to be concentrated in a compact nuclear region. We thus find no evidence for luminous, extended CO(1–0) components in the molecular gas reservoirs around our target quasars.

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48

Cheng, F. H., J. H. You, and M. Yan. "Cerenkov redshift and the redshift difference among broad emission lines of quasars and active galactic nuclei." Physics Letters A 138, no. 4-5 (June 1989): 165–67. http://dx.doi.org/10.1016/0375-9601(89)90020-0.

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49

Ubachukwu, A. A. "Implications of a Nonzero Cosmological Constant and Luminosity Selection Effects on Cosmological Tests." Australian Journal of Physics 51, no. 3 (1998): 585. http://dx.doi.org/10.1071/p97097.

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This paper examines the implications of a nonzero cosmological constant Λ 0 on the amount of linear size evolution and the luminosity selection effects usually required in the interpretation of the angular diameter–redshift (θ–z) test. This is based on three typical cases chosen on various plausible assumptions which can be made concerning the contribution of Λ 0 to the density of the universe (parametrised by ?0). The results show that a fairly strong linear size evolution will be required to interpret the θ–z data of extended steep spectrum quasars for all three cases, if luminosity effects are neglected. However, this evolution is significantly steeper in a matter-dominated universe with ?M = ?0 = 1 than in both the flat universe with ?Λ = 0·8, ?M = 0·2 and an open universe with ?M = 0·2, Λ = 0. Furthermore, when the luminosity selection effects present in the sample are considered, a milder size evolution is obtained for the ?M = 1, ?Λ = 0 model while little or no size evolution is found for the other two cases. There is therefore no significant difference in our results for an open low density universe with ?Λ = 0 and a flat universe dominated by ?Λ predicted by inflation. The present results therefore imply that an open low density universe with ?M = 0·2 and ?Λ = 0 is compatible with an inflationary model of the universe with ?M = 0·2 and ?Λ = 0 · 8. This leads to a contradiction since the universe cannot be open and spatially closed at the same time (the existence of one should preclude the other).

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50

Franceschini, Alberto. "The Source Populations Producing the Cosmic IR Background." Symposium - International Astronomical Union 204 (2001): 283–99. http://dx.doi.org/10.1017/s0074180900226181.

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Deep surveys performed with millimetric telescopes and with the Infrared Space Observatory have partly resolved the Cosmic IR Background (CIRB) into a population of IR sources characterized by extremely high rates of cosmological evolution (comparable to or higher than those observed for quasars). We report in this paper on early attempts to study these sources and to understand their physics. The IR multi-wavelength galaxy statistics can be explained by assuming, for the bulk of the IR population, spectra typical of starbursts, an indication that stellar more than quasar activity produces the IR emission by faint galaxies. From our fits to the observed optical-IR SEDs, the latter appear to mostly include massive galaxies hosting violent starbursts (SFR ~ 100 M⊙/yr). We interpret the strong redshift-evolution as an increase with z of the rate of interactions between galaxies (density evolution) and an increase of their IR luminosity due to the more abundant fuel available in the past (luminosity evolution). Our evolutionary scheme considers a bimodal star formation (SF) in galaxies, including long-lived quiescent SF, and enhanced SF taking place during transient events triggered by interactions and merging. The large energy content in the CIRB may possibly require a top-heavy stellar IMF associated with the starburst phase. The observed evolution of galaxy IR emissivity is so strong from z=0 to z ~ 1 that the CIRB spectral shape imposes a fast turnover to the evolution at z > 1: scenarios in which a relevant fraction of stellar formation occurs at very high-z (e.g., the bulk of stars in spheroids) are not supported by our analysis.

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Journal articles on the topic 'Quasars. 0'

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