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Related papers: The optically-selected 1.4-GHz quasar luminosity f…

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We have utilized the largest sample of $\gamma$-ray selected Fermi flat-spectrum radio quasars (FSRQs) ever used (519 sources) to construct the luminosity function and its evolution through the cosmic history. In addition to spanning large…

High Energy Astrophysical Phenomena · Physics 2025-12-02 Garima Rajguru , Lea Marcotulli , Marco Ajello , Mattia Di Mauro , Meg Urry

We applied image stacking on empty-field Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey maps centred on optically identified high-redshift quasars at $z\geq4$ to uncover the hidden $\mu$Jy radio emission in these active…

Astrophysics of Galaxies · Physics 2020-07-07 Krisztina Perger , Sándor Frey , Krisztina É. Gabányi , L. Viktor Tóth

We study the radio properties of moderately obscured quasars over a range of redshifts to understand the role of radio activity in accretion using the Jansky Very Large Array (JVLA) at 6.0GHz and 1.4GHz. Our z~2.5 sample consists of…

Astrophysics of Galaxies · Physics 2016-08-31 Rachael M. Alexandroff , Nadia L. Zakamska , Sjoert van Velzen , Jenny E. Greene , Michael A. Strauss

We present VLT/ISAAC near-infrared imaging of the host galaxies of 15 low luminosity quasars at 1 < z < 2. This work complements our studies to trace the cosmological evolution of the host galaxies of high luminosity quasars. The radio-loud…

Astrophysics · Physics 2009-11-13 J. K. Kotilainen , R. Falomo , A. Treves , M. Uslenghi

We present the result of our low-luminosity quasar survey in the redshift range of 4.5 < z < 5.5 in the COSMOS field. Using the COSMOS photometric catalog, we selected 15 quasar candidates with 22 < i' < 24 at z~5, that are ~ 3 mag fainter…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 H. Ikeda , T. Nagao , K. Matsuoka , Y. Taniguchi , Y. Shioya , M. Kajisawa , M. Enoki , P. Capak , F. Civano , A. M. Koekemoer , D. Masters , T. Morokuma , M. Salvato , E. Schinnerer , N. Z. Scoville

We present deep HST/WFPC2, rest-frame U images of 17 ~L* quasars at z=1 and z=2 (V and I bands respectively), designed to explore the host galaxies. We fit the images with simple axisymmetric galaxy models, including a point-source, in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 David J. E. Floyd , James S. Dunlop , Marek J. Kukula , Michael J. I. Brown , Ross J. McLure , Stefi A. Baum , Christopher P. O'Dea

Low-frequency radio surveys are ideal for selecting orientation-independent samples of extragalactic sources because the sample members are selected by virtue of their isotropic steep-spectrum extended emission. We use the new 7C Redshift…

Astrophysics · Physics 2009-10-31 Chris J. Willott , Steve Rawlings , Katherine M. Blundell , Mark Lacy

We use a principal components analysis of radio-selected (3CRR, 6CE and 7CRS) AGN datasets to define two parameters related to low-frequency (151 MHz) radio luminosity L_151 and [OIII] luminosity L_[OIII]: a parameter alpha encoding the…

Astrophysics · Physics 2009-11-10 Jennifer A. Grimes , Steve Rawlings , Chris J. Willott

(abridged) We use the 1.4 GHz VIMOS-VLA Deep Survey and the optical VVDS and the CFHT-LS to compare the properties of radio loud galaxies with respect to the whole population of optical galaxies. The availability of multiband photometry and…

We present a model to predict the luminosity function for radio galaxies and their linear size distribution at any redshift. The model takes a black hole mass function and Eddington ratio distribution as input and tracks the evolution of…

Astrophysics of Galaxies · Physics 2017-06-28 A. Saxena , H. J. A. Röttgering , E. E. Rigby

We present Very Large Array (VLA) observations at 1.4 GHz and 5 GHz of a sample of 12 Quasi-stellar Objects (QSOs) at z = 3.99 to 4.46. The sources were selected as the brightest sources at 250 GHz from the recent survey of Omont et al.…

Astrophysics · Physics 2009-11-06 C. L. Carilli , F. Bertoldi , A. Omont , P. Cox , R. G. McMahon , K. G. Isaak

We take a sample of 94 ultraluminous, optical quasars from the search of over 14,486 deg^2 by Onken et al. 2022 in the range 4.4<redshift<5.2 and match them against the Rapid ASKAP Continuum Survey (RACS) observed on the Australian Square…

Astrophysics of Galaxies · Physics 2023-09-04 Philip Lah , Christopher A. Onken , Ray P. Norris , Francesco D'Eugenio

Optically luminous quasars at $z > 5$ are important probes of super-massive black hole (SMBH) formation. With new and future radio facilities, the discovery of the brightest low-frequency radio sources in this epoch would be an important…

We report observations of the low-luminosity z = 5.50 quasar RD J030117+002025 (RD0301 hereafter) at 250 GHz (1.20mm) using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-meter telescope. The quasar was detected with a…

Astrophysics · Physics 2009-11-07 F. Bertoldi , P. Cox

Quasars at redshifts $z>6$ are an excellent probe of the formation and evolution of supermassive black holes in the early Universe. The population of radio-luminous quasars is of particular interest, as such quasars could potentially be…

Astrophysics of Galaxies · Physics 2024-02-15 Pascal M. Keller , Nithyanandan Thyagarajan , Ajay Kumar , Nissim Kanekar , Gianni Bernardi

We use new 144 MHz observations over 5634 deg$^2$ from the LOFAR Two-metre Sky Survey (LoTSS) to compile the largest sample of uniformly-selected, spectroscopically-confirmed quasars from the 14th data release of the Sloan Digital Sky…

Fermi has provided the largest sample of {\gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 M. Ajello , M. S. Shaw , R. W. Romani , C. D. Dermer , L. Costamante , O. G. King , W. Max-Moerbeck , A. Readhead , A. Reimer , J. L. Richards , M. Stevenson

We have developed a flexible framework for constructing physical models of quasar evolution that can incorporate a wide variety of observational constraints, such as multi-wavelength quasar luminosity functions (QLFs), estimated masses and…

Astrophysics · Physics 2017-08-23 Adam Steed , David H. Weinberg

We present details of a new sample of radio-loud quasars drawn from 0.013 sr of the 7C Redshift Survey. This sample is small (21 quasars) but complete in that every object with an unresolved nucleus and/or broad emission lines with…

Astrophysics · Physics 2016-01-27 Chris J. Willott , Steve Rawlings , Katherine M. Blundell , Mark Lacy