نتایج جستجو برای: agn
تعداد نتایج: 7335 فیلتر نتایج به سال:
Nuclear and starburst activity are known to often occur concomitantly. Herschel-SPIRE provides sampling of the far-infrared (FIR) spectral energy distributions (SEDs) of type 1 and type 2 AGN, allowing for the separation between the hot dust (torus) and cold dust (starburst) emission. We study large samples of spectroscopically confirmed type 1 and type 2 AGN lying within the Herschel Multi-tie...
We present QSFit, a new software package to automatically perform the analysis of Active Galactic Nuclei (AGN) optical spectra. The software provides luminosity estimates for the AGN continuum, the Balmer continuum, both optical and UV iron blended complex, host galaxy and emission lines, as well as width, velocity offset and equivalent width of 20 emission lines. Improving on a number of previ...
Context. Observations indicate a strong link between star formation and black hole (BH) growth, but some questions remain unanswered: whether both activities are coeval or whether one precedes the other, what their characteristic timescales are, and what kinds of physical processes are responsible for this interplay. Aims. We examine stellar and BH masses (M∗ and MBH) in z∼2 active systems at t...
We present a series of three-dimensional hydrodynamical simulations of central active galactic nuclei (AGN)-driven jets in a dynamic, cosmologically evolved galaxy cluster. Extending previous work, we study jet powers ranging from Ljet = 1044 erg s−1 to Ljet = 1046 erg s−1 and in duration from 30 to 200 Myr. We find that large-scale motions of cluster gas disrupt the AGN jets, causing energy to...
Radio outflows of active galactic nuclei (AGN) are invoked in cosmological models as a key feedback mechanism in the latest phases of massive galaxy formation. Recently it has been suggested that the two major radio AGN populations – the powerful high-excitation, and the weak low-excitation radio AGN (HERAGN and LERAGN, resp.) – represent two earlier and later stages of massive galaxy build-up....
We constrain the number density and evolution of Compton-thick Active Galactic Nuclei (AGN). In the local Universe we use the wide area surveys from the Swift and INTEGRAL satellites, while for high redshifts we explore candidate selections based on a combination of X-ray and mid-IR parameters. We find a significantly lower space density of Compton-thick AGN in the local Universe than expected ...
Current emission-line based estimates of the metallicity of active galactic nuclei (AGN) at both high and low redshifts indicate that AGN have predominantly solar to supersolar metallicities. This leads to the question: do low metallicity AGN exist? In this paper we use photoionization models to examine the effects of metallicity variations on the narrow emission lines from an AGN. We explore a...
We present X-ray and optical analysis of 188 AGN identified from 497 hard X-ray (f2.0−8.0keV > 2.7×10 erg cm s ) sources in 20 Chandra fields (1.5 deg) forming part of the Chandra Multiwavelength Project. These medium depth X-ray observations enable us to detect a representative subset of those sources responsible for the bulk of the 2–8 keV Cosmic X-ray Background. Brighter than our optical sp...
The Great Observatories Origins Deep Survey (GOODS) combines deep HST and Spitzer imaging with the deepest Chandra/XMM observations to probe obscured AGN at higher redshifts than previous multiwavelength surveys. We present a self-consistent implementation of the AGN unification paradigm, which postulates obscured AGN wherever there are unobscured AGN, to successfully explain the infrared, opti...
Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter haloes in which they reside is key to constraining how black hole fuelling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modelling. In practice, these approaches rem...
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