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Type II quasars are luminous AGNs whose central engines and broad-line regions are obscured by intervening material; such objects only recently have been discovered in appreciable numbers. We study the multiwavelength properties of 291 type…

We present photometry of the large scale environments of a sample of twelve broad line AGN with $0.06 < z < 0.37$ from deep images in the SDSS $u$, $g$, $r$, and $i$ filters taken with the 90Prime prime focus camera on the Steward…

Astrophysics of Galaxies · Physics 2015-04-15 Jennifer E. Scott , Alireza Rafiee , Jill Bechtold , Erica Ellingson , Christopher Thibodeau , Michael Richmond

The Gigahertz Peaked Spectrum (GPS) sources, Compact Steep Spectrum (CSS) radio sources, and High Frequency Peakers (HFP) radio sources are thought to be young radio AGNs, at the early stage of AGN evolution. We investigated the optical…

Astrophysics of Galaxies · Physics 2019-12-11 Mai Liao , Minfeng Gu

Maintenance-mode feedback from low-accretion rate AGN, manifesting itself observationally through radio-loudness, is invoked in all cosmological galaxy formation models as a mechanism that prevents excessive star-formation in massive…

We investigate the environments of both X-ray and radio-loud AGN within the UKIDSS Ultra-deep Survey (UDS) using deep infrared selection to sample the galaxy density field in the redshift range 1.0 <= z <= 1.5. Using angular…

We present a new approach to tackle the issue of radio loudness in quasars. We constrain a (simple) prescription for the intrinsic distribution of radio-to-optical ratios by comparing properties of Monte Carlo simulated samples with those…

Astrophysics · Physics 2009-11-10 M. Cirasuolo , A. Celotti , M. Magliocchetti , L. Danese

We study the differences in X-ray properties of luminous radio galaxies and their radio-quiet counterparts. In order to avoid biases associated with the dependence of X-ray properties on the black hole mass and Eddington ratio, the…

High Energy Astrophysical Phenomena · Physics 2018-08-29 Maitrayee Gupta , Marek Sikora , Katarzyna Rusinek , Greg M. Madejski

We use the ROSAT All-Sky Survey to study the X-ray properties of a sample of 625 groups and clusters of galaxies selected from the Sloan Digital Sky Survey. We stack clusters with similar velocity dispersions and investigate whether their…

A toy model for jet powers and radio loudness of active galactic nuclei (AGNs) is proposed based on the coexistence of the Blandford-Znajek (BZ) and magnetic coupling (MC) processes (CEBZMC) in black hole (BH) accretion disc. It turns out…

Astrophysics · Physics 2016-08-30 Yong-Chun Ye , Ding-Xiong Wang

GPS and CSS radio sources are the objects of choice to investigate the evolution of young radio-loud AGN. Previous investigations, mainly based on number counts and source size distributions, indicate that GPS/CSS sources decrease…

Astrophysics · Physics 2009-11-07 I. A. G. Snellen , K. -H. Mack , R. T. Schilizzi , W. Tschager

It is now established that the faint radio population is a mixture of star-forming galaxies and faint active galactic nuclei (AGNs), with the former dominating below S(1.4GHz) \sim 100 muJy and the latter at larger flux densities. The faint…

Astrophysics of Galaxies · Physics 2018-12-26 R. Ricci , I. Prandoni , H. R. De Ruiter , P. Parma

Typical blazars seem to be associated with FR I and FR II radio galaxies and radio-loud quasars. However, what happens at lower powers? Do blazars exist in low-luminosity AGN or do they exist in radio-quiet AGN? A recent detection of…

Astrophysics · Physics 2007-05-23 Heino Falcke , Sera Markoff , Peter L. Biermann

The physical origin of radio emission in Radio Quiet Active Galactic Nuclei (RQ AGN) remains unclear, whether it is a downscaled version of the relativistic jets typical of Radio Loud (RL) AGN, or whether it originates from the accretion…

Astrophysics of Galaxies · Physics 2015-08-06 Ehud Behar , Ranieri D. Baldi , Ari Laor , Assaf Horesh , Jamie Stevens , Tasso Tzioumis

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

Radio-loud high-redshift quasars (RHRQs) provide crucial insights into the evolution of relativistic jets and their connection to the growth of supermassive black holes. Beyond the extensively studied population at $z \ge 5$, the cosmic…

Astrophysics of Galaxies · Physics 2025-12-08 Yingkang Zhang , Ruqiu Lin , Krisztina Perger , Sándor Frey , Tao An , Xiang Ji , Qiqi Wu , Shilong Liao

We present a comprehensive census of the AGNs in the GOODS-S/HUDF region from the X-ray to the radio, covering both the obscured and unobscured populations. This work includes a robust analysis of the source optical-to-mid-IR SEDs featuring…

Astrophysics of Galaxies · Physics 2023-01-04 Jianwei Lyu , Stacey Alberts , George H. Rieke , Wiphu Rujopakarn

It is still a mystery why only a small fraction of active galactic nuclei (AGNs) contain relativistic jets. Strong magnetic field is a necessary ingredient for jet formation, however, the advection of the external field in a geometrically…

High Energy Astrophysical Phenomena · Physics 2016-12-14 Xinwu Cao

We construct the first X-ray selected sample of broad line radio-loud AGN from the EMSS survey. In order to test unifying schemes for radio-loud objects, their spectral and statistical properties (both flat and steep spectrum objects) are…

Astrophysics · Physics 2009-11-06 Anna Wolter , Annalisa Celotti

The large-scale Universal structure comprises strands of dark matter and galaxies with large under-dense volumes known as voids. We measure the fraction of the line of sight that intersects voids for active galactic nuclei (AGN) detected by…

High Energy Astrophysical Phenomena · Physics 2025-01-24 Amy Furniss , Josepf N. Amador , Olivier Hervet , Ollie Jackson , David A. Williams

While supermassive black holes are ubiquitous features of galactic nuclei, only a small minority are observed during episodes of luminous accretion. The physical mechanism(s) driving the onset of fueling and ignition in these active…

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