AGN Populations in Large-volume X-Ray Surveys: Photometric Redshifts and Population Types Found in the Stripe 82X Survey

Ananna, Tonima Tasnim; Salvato, M.; LaMassa, Stephanie; Urry, C. Megan; Cappelluti, N.; Cardamone, Carolin N.; Civano, F.; Farrah, D.; Gilfanov, M.; Glikman, Eilat; Hamilton, Mark G.; Kirkpatrick, Allison; Lanzuisi, G.; Marchesi, S.; Merloni, A.; Nandra, K.; Natarajan, Priyamvada; Richards, Gordon T.; Timlin, John

doi:10.3847/1538-4357/aa937d

Cited by 78 publications

(148 citation statements)

References 117 publications

(144 reference statements)

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“…While 54% of the sources in S82X currently have spectroscopic redshifts, nearly all remaining objects have photometric redshifts (Ananna et al 2017). In order to maximize the information we extract from those photometric redshifts, we utilize the full PDFs following the method in Allevato et al (2016); each galaxy is essentially 'spread out' through redshift space and sampled by its normalized PDF.…”

Section: Utilizing Full Photo-z Pdfsmentioning

confidence: 99%

The Clustering of X-Ray Luminous Quasars

Powell

Urry

Cappelluti

et al. 2020

ApJ

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The clustering of active galactic nuclei (AGN) sheds light on their typical large (Mpc-scale) environments, which can constrain the growth and evolution of supermassive black holes. Here we measure the clustering of luminous X-ray-selected AGN in the Stripe 82X and XMM-XXL-north surveys around the peak epoch of black hole growth, in order to investigate the dependence of luminosity on largescale AGN environment. We compute the auto-correlation function of AGN in two luminosity bins, 10 43 ≤ L X < 10 44.5 erg s −1 at z ∼ 0.8 and L X ≥ 10 44.5 erg s −1 at z ∼ 1.8, and calculate the AGN bias taking into account the redshift distribution of the sources using three different methods. Our results show that while the less luminous sample has an inferred typical halo mass that is smaller than for the more luminous AGN, the host halo mass may be less dependent on luminosity than suggested in previous work. Focusing on the luminous sample, we calculate a typical host halo mass of ∼ 10 13 M h −1 , which is similar to previous measurements of moderate-luminosity X-ray AGN and significantly larger than the values found for optical quasars of similar luminosities and redshifts. We suggest that the clustering differences between different AGN selection techniques are dominated by selection biases, and not due to a dependence on AGN luminosity. We discuss the limitations of inferring AGN triggering mechanisms from halo masses derived by large-scale bias.

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Section: Utilizing Full Photo-z Pdfsmentioning

confidence: 99%

The Clustering of X-Ray Luminous Quasars

Powell

Urry

Cappelluti

et al. 2020

ApJ

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“…Following the convention in the literature (e.g., Ilbert et al 2009;Ananna et al 2017;Fotopoulou & Paltani 2018), we estimate the photometric redshift accuracy using the normalised median absolute deviation defined as…”

Section: Photometric Redshift Estimationmentioning

confidence: 99%

Catalogues of active galactic nuclei from Gaia and unWISE data

Shu

Koposov

Evans

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys -Data Release 2 (DR2) of the Gaia mission and the unWISE catalogue of the Wide-field Infrared Survey Explorer (WISE ). We train a random forest classifier to predict the probability of each source in the Gaia-unWISE joint sample being an AGN, P RF , based on Gaia astrometric and photometric measurements and unWISE photometry. The two catalogues, which we designate C75 and R85, are constructed by applying different P RF threshold cuts to achieve an overall completeness of 75% (≈90% at Gaia G ≤ 20 mag) and reliability of 85% respectively. The C75 (R85) catalogue contains 2, 734,464 (2,182,193) AGN candidates across the effective 36,000 deg 2 sky, of which ≈0.91 (0.52) million are new discoveries. Photometric redshifts of the AGN candidates are derived by a random forest regressor using Gaia and WISE magnitudes and colours. The estimated overall photometric redshift accuracy is 0.11. Cross-matching the AGN candidates with a sample of known bright cluster galaxies, we identify a high-probability strongly-lensed AGN candidate system, SDSS J1326+4806, with a large image separation of 21. 06. All the AGN candidates in our catalogues will have ∼5-year long light curves from Gaia by the end of the mission, and thus will be a great resource for AGN variability studies. Our AGN catalogues will also be helpful in AGN target selections for future spectroscopic surveys, especially ones in the southern hemisphere. The C75 catalogue can be downloaded at https://www.ast.cam.ac.uk/~ypshu/AGN_Catalogues.html

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“…The observed colours of SEDs as a function of redshift illustrate how they fill the colour-space and can reveal how individual spectral features impact broadband colours. To benchmark our work, we compare the colours produced by our SEDs to the Brown et al (2014b) galaxy SEDs, which largely lack powerful AGNs, and the Ananna et al (2017) galaxy and AGN SEDs, which are a recent iteration of AGN SEDs used for the SWIRE, CDF-S and COSMOS surveys (Polletta et al 2007;Salvato et al 2009;Hsu et al 2014;Ananna et al 2017). The Ananna et al (2017) suite of SEDs is also optimised for the wide-field Stripe 82 region, and thus may be directly comparable to our work (i.e.…”

Section: The Colours Of Agnsmentioning

confidence: 99%

The spectral energy distributions of active galactic nuclei

Brown

Duncan

Landt

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present spectral energy distributions (SEDs) of 41 active galactic nuclei, derived from multiwavelength photometry and archival spectroscopy. All of the SEDs span at least 0.09 to 30 µm, but in some instances wavelength coverage extends into the X-ray, far-infrared and radio. For some AGNs we have fitted the measured far-infrared photometry with greybody models, while radio flux density measurements have been approximated by power-laws or polynomials. We have been able to fill some of the gaps in the spectral coverage using interpolation or extrapolation of simple models. In addition to the 41 individual AGN SEDs, we have produced 72 Seyfert SEDs by mixing SEDs of the central regions of Seyferts with galaxy SEDs. Relative to the literature, our templates have broader wavelength coverage and/or higher spectral resolution. We have tested the utility of our SEDs by using them to generate photometric redshifts for 0 < z ≤ 6.12 AGNs in the Boötes field (selected with X-ray, IR and optical criteria) and, relative to SEDs from the literature, they produce comparable or better photometric redshifts with reduced flux density residuals.

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AGN Populations in Large-volume X-Ray Surveys: Photometric Redshifts and Population Types Found in the Stripe 82X Survey

Cited by 78 publications

References 117 publications

The Clustering of X-Ray Luminous Quasars

The Clustering of X-Ray Luminous Quasars

Catalogues of active galactic nuclei from Gaia and unWISE data

The spectral energy distributions of active galactic nuclei

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