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The Chandra Multi-wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-Ray-selected AGNs

Trichas, Markos and Green, Paul J. and Silverman, John D. and Aldcroft, Tom and Barkhouse, Wayne and Cameron, Robert A. and Constantin, Anca and Ellison, Sara L. and Foltz, Craig and Haggard, Daryl and Jannuzi, Buell T. and Kim, Dong-Woo and Marshall, Herman L. and Mossman, Amy and Pérez, Laura M. and Romero-Colmenero, Encarni and Ruiz, Angel and Smith, Malcolm G. and Smith, Paul S. and Torres, Guillermo and Wik, Daniel R. and Wilkes, Belinda J. and Wolfgang, Angie (2012) The Chandra Multi-wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-Ray-selected AGNs. Astrophysical Journal Supplement Series, 200 (2). Art. No. 17. ISSN 0067-0049.

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From optical spectroscopy of X-ray sources observed as part of the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow-up using the FLWO/1.5 m, SAAO/1.9 m, WIYN 3.5 m, CTIO/4 m, KPNO/4 m, Magellan/6.5 m, MMT/6.5 m, and Gemini/8 m telescopes, and from archival Sloan Digital Sky Survey (SDSS) spectroscopy. We classify the optical counterparts as 50% broad-line active galactic nuclei (AGNs), 16% emission line galaxies, 14% absorption line galaxies, and 20% stars. We detect QSOs out to z ~ 5.5 and galaxies out to z ~ 3. We have compiled extensive photometry, including X-ray (ChaMP), ultraviolet (GALEX), optical (SDSS and ChaMP-NOAO/MOSAIC follow-up), near-infrared (UKIDSS, Two Micron All Sky Survey, and ChaMP-CTIO/ISPI follow-up), mid-infrared (WISE), and radio (FIRST and NVSS) bands. Together with our spectroscopic information, this enables us to derive detailed spectral energy distributions (SEDs) for our extragalactic sources. We fit a variety of template SEDs to determine bolometric luminosities, and to constrain AGNs and starburst components where both are present. While ~58% of X-ray Seyferts (10^(42) erg s^(–1) < L_(2 – 10 keV) <10^(44) erg s^(–1)) require a starburst event (>5% starburst contribution to bolometric luminosity) to fit observed photometry only 26% of the X-ray QSO (L_(2 – 10 keV) >10^(44) erg s^(–1)) population appear to have some kind of star formation contribution. This is significantly lower than for the Seyferts, especially if we take into account torus contamination at z > 1 where the majority of our X-ray QSOs lie. In addition, we observe a rapid drop of the percentage of starburst contribution as X-ray luminosity increases. This is consistent with the quenching of star formation by powerful QSOs, as predicted by the merger model, or with a time lag between the peak of star formation and QSO activity. We have tested the hypothesis that there should be a strong connection between X-ray obscuration and star formation but we do not find any association between X-ray column density and star formation rate both in the general population or the star-forming X-ray Seyferts. Our large compilation also allows us to report here the identification of 81 X-ray Bright Optically inactive Galaxies, 78 z > 3 X-ray sources, and eight Type-2 QSO candidates. Also, we have identified the highest redshift (z = 5.4135) X-ray-selected QSO with optical spectroscopy.

Item Type:Article
Related URLs:
URLURL TypeDescription
Green, Paul J.0000-0002-8179-9445
Silverman, John D.0000-0002-0000-6977
Constantin, Anca0000-0002-2441-1619
Ellison, Sara L.0000-0002-1768-1899
Haggard, Daryl0000-0001-6803-2138
Jannuzi, Buell T.0000-0002-1578-6582
Pérez, Laura M.0000-0002-1199-9564
Ruiz, Angel0000-0002-7292-3002
Torres, Guillermo0000-0002-5286-0251
Wik, Daniel R.0000-0001-8952-676X
Wilkes, Belinda J.0000-0003-1809-2364
Additional Information:© 2012 American Astronomical Society. Received 2011 December 23; accepted 2012 April 21; published 2012 May 30. The authors thank Francesca Civano and Hagai Netzer for their useful comments. Support for this work was provided by the National Aeronautics and Space Administration through Chandra Award nos. AR9-0020X and AR1-12016X, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060.
Funding AgencyGrant Number
Subject Keywords:galaxies: evolution; galaxies: Seyfert; galaxies: starburst; quasars: general; techniques: spectroscopic; X-rays: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20120711-131851896
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Official Citation:The Chandra Multi-wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-Ray-selected AGNs Markos Trichas et al. 2012 ApJS 200 17
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:32358
Deposited By: Jason Perez
Deposited On:11 Jul 2012 22:43
Last Modified:09 Mar 2020 13:19

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