The Fall of Active Galactic Nuclei and the Rise of Star-forming Galaxies: A Close Look at the Chandra Deep Field X-Ray Number Counts

2004 ◽  
Vol 128 (5) ◽  
pp. 2048-2065 ◽  
Author(s):  
F. E. Bauer ◽  
D. M. Alexander ◽  
W. N. Brandt ◽  
D. P. Schneider ◽  
E. Treister ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Star Forming ◽  
Number Counts

scholarly journals X-ray bright active galactic nuclei in massive galaxy clusters – I. Number counts and spatial distribution

2012 ◽  
Vol 428 (4) ◽  
pp. 3509-3525 ◽  
Author(s):  
S. Ehlert ◽  
S. W. Allen ◽  
W. N. Brandt ◽  
Y. Q. Xue ◽  
B. Luo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Galactic Nuclei ◽  
X Ray ◽  
Number Counts ◽  
Massive Galaxy

scholarly journals Active galactic nuclei and star-forming galaxies - contributing to the extragalactic X-ray flux

1992 ◽  
Vol 255 (4) ◽  
pp. 545-556 ◽  
Author(s):  
R. E. Griffiths ◽  
I. R. Tuohy ◽  
R. J. V. Brissenden ◽  
M. J. Ward
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Star Forming

scholarly journals THENuSTAREXTRAGALACTIC SURVEYS: THE NUMBER COUNTS OF ACTIVE GALACTIC NUCLEI AND THE RESOLVED FRACTION OF THE COSMIC X-RAY BACKGROUND

2016 ◽  
Vol 831 (2) ◽  
pp. 185 ◽  
Author(s):  
F. A. Harrison ◽  
J. Aird ◽  
F. Civano ◽  
G. Lansbury ◽  
J. R. Mullaney ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
X Ray Background ◽  
Number Counts

scholarly journals Host galaxy properties and environment of obscured and unobscured X-ray selected active galactic nuclei in the COSMOS survey

2020 ◽  
Vol 494 (1) ◽  
pp. 1189-1202 ◽  
Author(s):  
C Bornancini ◽  
D García Lambas
Keyword(s):  
Active Galactic Nuclei ◽  
Formation Rate ◽  
Control Sample ◽  
Galactic Nuclei ◽  
Local Environment ◽  
Spectroscopic Properties ◽  
Stellar Mass ◽  
Host Galaxy ◽  
X Ray ◽  
Star Forming

ABSTRACT We analyse different photometric and spectroscopic properties of active galactic nuclei (AGNs) and quasars (QSOs) selected by their mid-IR power-law and X-ray emission from the COSMOS survey. We use a set of star-forming galaxies as a control sample to compare with the results. We have considered samples of obscured (HR > −0.2) and unobscured (HR < −0.2) sources including AGNs with LX < 1044 erg s−1, as well as QSOs (LX > 1044 erg s−1) with 1.4 ≤ z ≤ 2.5. We also study the typical environment of these samples, by assessing neighbouring galaxy number density and neighbour properties such as colour, stellar mass, and star formation rate. We find that the UV/optical and mid-infrared colour distribution of the different AGN types differ significantly. Also, we obtain most of AGNs and QSOs to be more compact when compared to the sample of SF galaxies. In general we find that the stellar mass distribution of the different AGN sample are similar, obtaining only a difference of $\Delta \overline{\mathrm{log}M}=0.3$ dex (M⊙) between unobscured and obscured QSOs. Obscured and unobscured AGNs and QSOs reside in different local environment at small (rp < 100 kpc) scales. Our results support previous findings where AGN type correlates with environment. These differences and those found in AGN host properties cast out the simplest unified model in which obscuration is purely an orientation effect.

scholarly journals LIFTING THE VEIL ON OBSCURED ACCRETION: ACTIVE GALACTIC NUCLEI NUMBER COUNTS AND SURVEY STRATEGIES FOR IMAGING HARD X-RAY MISSIONS

2011 ◽  
Vol 736 (1) ◽  
pp. 56 ◽  
Author(s):  
D. R. Ballantyne ◽  
A. R. Draper ◽  
K. K. Madsen ◽  
J. R. Rigby ◽  
E. Treister
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
The Veil ◽  
Number Counts ◽  
Nuclei Number

scholarly journals The X-Ray Background from Star-Forming Galaxies

1990 ◽  
Vol 139 ◽  
pp. 412-413
Author(s):  
Richard E. Griffiths
Keyword(s):  
Energy Range ◽  
Active Galactic Nuclei ◽  
Surface Density ◽  
Galactic Nuclei ◽  
X Ray ◽  
Star Forming ◽  
Smooth Component ◽  
Spatial Fluctuations ◽  
Deep Survey ◽  
X Ray Background

It has been established observationally that at least 30% of the all-sky X-ray background (XRB) in the energy range of 1–3 keV comes from active galactic nuclei (AGN) in the redshift interval of 0.4 to 1.2 (Griffiths et al. 1983, 1988); it is also quite plausible that AGN contribute half of the XRB in the 1–3 keV range (Morisawa and Takahara 1989). However, analysis of spatial fluctuations in the Einstein deep survey counts (Hamilton and Helfand 1987; Barcons and Fabian 1989) has indicated the presence of a relatively smooth component of the XRB with a corresponding surface density of discrete sources of at least several thousand per square degree.

scholarly journals X-rays from Green Pea analogues

2017 ◽  
Vol 470 (1) ◽  
pp. 606-611 ◽  
Author(s):  
M. Brorby ◽  
P. Kaaret
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
High Mass ◽  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
Green Pea ◽  
X Ray Binaries

Abstract X-ray observations of two metal-deficient luminous compact galaxies (LCG; SHOC 486 and SDSS J084220.94+115000.2) with properties similar to the so-called Green Pea galaxies were obtained using the Chandra X-ray Observatory. Green Pea galaxies are relatively small, compact (a few kpc across) galaxies that get their green colour from strong [O iii] λ5007 Å emission, an indicator of intense, recent star formation. These two galaxies were predicted to have the highest observed count rates, using the X-ray luminosity–star formation rate (LX–SFR) relation for X-ray binaries, from a statistically complete sample drawn from optical criteria. We determine the X-ray luminosity relative to SFR and metallicity for these two galaxies. Neither exhibits any evidence of active galactic nuclei, and we suspect that the X-ray emission originates from unresolved populations of high-mass X-ray binaries. We discuss the LX–SFR–metallicity plane for star-forming galaxies and show that the two LCGs are consistent with the prediction of this relation. This is the first detection of Green Pea analogues in X-rays.

Obscured Active Galactic Nuclei and the X‐Ray, Optical, and Far‐Infrared Number Counts of Active Galactic Nuclei in the GOODS Fields

2004 ◽  
Vol 616 (1) ◽  
pp. 123-135 ◽  
Author(s):  
Ezequiel Treister ◽  
C. Megan Urry ◽  
Eleni Chatzichristou ◽  
Franz Bauer ◽  
David M. Alexander ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
X Ray ◽  
Number Counts

scholarly journals Forward modelling the multiwavelength properties of active galactic nuclei: application to X-ray and WISE mid-infrared samples

2020 ◽  
Vol 499 (1) ◽  
pp. 710-729
Author(s):  
Antonis Georgakakis ◽  
Angel Ruiz ◽  
Stephanie M LaMassa
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Electromagnetic Spectrum ◽  
Forward Modelling ◽  
Sharp Drop ◽  
Mid Infrared ◽  
X Ray ◽  
Star Forming ◽  
Modelling Framework

ABSTRACT An empirical forward-modelling framework is developed to interpret the multiwavelength properties of active galactic nuclei (AGNs) and provide insights into the overlap and incompleteness of samples selected at different parts of the electromagnetic spectrum. The core of the model are observationally derived probabilites on the occupation of galaxies by X-ray-selected AGN. These are used to seed mock galaxies drawn from stellar-mass functions with accretion events and then associate them with spectral energy distributions that describe both the stellar and AGN emission components. This approach is used to study the complementarity between X-ray and WISE mid-infrared AGN selection methods. We first show that the basic observational properties of the X-ray and WISE AGN (magnitude and redshift distributions) are adequately reproduced by the model. We then infer the level of contamination of the WISE selection and show that this is dominated by non-AGN at redshifts z < 0.5. These are star-forming galaxies that scatter into the WISE AGN selection wedge because of photometric uncertainties affecting their colours. Our baseline model shows a sharp drop in the number density of heavily obscured AGN above the Compton-thick limit in the WISE bands. The model also overpredicts by a factor of 1.5 the fraction of X-ray associations in the WISE AGN selection box compared to observations. This suggests a population of X-ray faint sources that is not reproduced by the model. This discrepancy is discussed in the context of either heavily obscured or intrinsically X-ray weak AGN. Evidence is found in favour of the latter.

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