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We present archival high resolution X-ray imaging observations of 25 nearby LINERs observed by ACIS on board Chandra. This sample builds on our previously published proprietary and archival X-ray observations, and includes the complete set…

Astrophysics · Physics 2009-11-13 S. Satyapal , R. P. Dudik , B. O'Halloran , M. Gliozzi

In the unification scheme, narrow-lined (type 2) active galactic nuclei (AGN) are intrinsically similar to broad-lined (type 1) AGN with the exception that the line of sight to the broad emission line region and accretion disk is blocked by…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Yu Lu , Ting-Gui Wang , Xiao-Bo Dong , Hong-Yan Zhou

According to the unified model of active galactic nuclei (AGNs), a putative dusty torus plays an important role in determining their external appearance. However, very limited information is known about the physical properties of the torus.…

Astrophysics of Galaxies · Physics 2018-08-08 Ming-Yang Zhuang , Luis C. Ho , Jinyi Shangguan

According to theory, the torus of active galactic nuclei (AGN) is sustained from a wind coming off the accretion disk, and for low efficient AGN, it has been proposed that such structure disappears. However, the exact conditions for its…

A simple and versatile parameterized approach to the star formation history allows a quantitative investigation of the constraints from far infrared and submillimetre counts and background intensity measurements. The models include four…

Astrophysics · Physics 2011-06-21 M. Rowan-Robinson

The origin of obscuration in Active Galactic Nuclei (AGN) is still an open debate. In particular, it is unclear what drives the relative contributions to the line-of-sight column densities from galaxy-scale and torus-linked obscuration. The…

Studies show that both radio jets from the active galactic nuclei (AGN) and the star formation (SF) activity in quasar host galaxies contribute to the quasar radio emission; yet their relative contributions across the population remain…

The uncertainty surrounding the nature of the heating mechanism for the dust that emits at mid- to far-IR (MFIR) wavelengths in active galaxies limits our understanding of the links between active galactic nuclei (AGN) and galaxy evolution,…

The star formation activity of the host galaxies of active galactic nuclei (AGNs) provides valuable insights into the complex interconnections between black hole growth and galaxy evolution. A major obstacle arises from the difficulty of…

Astrophysics of Galaxies · Physics 2021-04-14 Yanxia Xie , Luis C. Ho , Ming-Yang Zhuang , Jinyi Shangguan

It is believed that, in radio-loud active galactic nuclei (AGN), the core radio flux density can be normalized to the flux density of the extended lobe emission to infer the orientation of a radio source. However very little is known about…

Astrophysics of Galaxies · Physics 2016-10-19 Frederic Marin , Robert Antonucci

We report the relationship between the luminosities of active galactic nuclei (AGNs) and the rates of star formation (SF) for a sample of 323 far-infrared (FIR)-detected AGNs. This sample has a redshift range of 0.2 $< z <$ 2.5, and spans…

Statistical studies of X-ray selected Active Galactic Nuclei (AGN) indicate that the fraction of obscured AGN increases with increasing redshift, and the results suggest that a significant part of the accretion growth occurs behind…

Weak emission-line active galactic nuclei (WLAGNs) are radio-quiet active galactic nuclei (AGNs) that have nearly featureless optical spectra. We investigate the ultraviolet to mid-infrared spectral energy distributions of 73 WLAGNs…

Astrophysics of Galaxies · Physics 2016-09-20 Xudong Zhang , Yuan Liu

Hard X-ray surveys have uncovered a large population of heavily obscured AGN. They also reveal a population of quasars with moderate obscuration at both visible and X-ray wavelengths. We use Chandra selected samples of quasars from the…

We investigate models for the power supply and broad-band spectral energy distribution (SED) of hyperluminous IR galaxies, recently discovered at high redshifts, in terms of the emission from an active nucleus embedded in a torus-like dusty…

Astrophysics · Physics 2009-10-28 Gian Luigi Granato , Luigi Danese , Alberto Franceschini

Active galactic nuclei (AGNs) are known to exhibit optical/UV variability and most of them can be well modeled by the damped random walks. Physical processes that are not related to the accretion disk, such as tidal disruption events (TDE)…

Astrophysics of Galaxies · Physics 2024-04-17 Zhiyuan Zheng , Yong Shi , Shuowen Jin , H. Dannerbauer , Qiusheng Gu , Xin Li , Xiaoling Yu

A significant number of active galactic nuclei (AGNs) are observed to be hidden behind dust and gas. The distribution of material around AGNs plays an important role in modeling the cosmic X-ray background (CXB), especially the fraction of…

High Energy Astrophysical Phenomena · Physics 2018-02-28 Raj Gohil , David R. Ballantyne

We have assembled a sample of 5 X-ray and submm-luminous z~2 QSOs which are therefore both growing their central black holes through accretion and forming stars copiously at a critical epoch. Hence, they are good laboratories to investigate…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-13 F. J. Carrera , A. K. Ali , M. J. Page , M. Symeonidis , J. A. Stevens , J. M. Cao Orjales

(abridged) This paper is the second part of a work investigating the properties of dusty tori in AGN by means of multi-component SED fitting. It focuses on low luminosity, low redshift (z < 0.25) AGN selected among emission line galaxies as…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Evanthia Hatziminaoglou , Jacopo Fritz , Tom Jarrett

We used the CLUMPY torus models and a Bayesian approach to fit the infrared spectral energy distributions (SEDs) and ground-based high-angular resolution mid-infrared spectroscopy of 13 nearby Seyfert galaxies. This allowed us to put tight…