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Date and Time of the Query: 2018-12-13 T09:46:16 PST
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For refcode 2010ApJ...716..530K:
There are 497368 NED objects in this reference.
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2010ApJ...716..530K Mid-infrared Variability from the Spitzer Deep Wide-field Survey Kozlowski, Szymon; Kochanek, Christopher S.; Stern, Daniel; Ashby, Matthew L. N.; Assef, Roberto J.; Bock, J. J.; Borys, C.; Brand, K.; Brodwin, M.; Brown, M. J. I.; Cool, R.; Cooray, A.; Croft, S.; Dey, Arjun; Eisenhardt, P. R.; Gonzalez, A.; Gorjian, V.; Griffith, R.; Grogin, N.; Ivison, R.; Jacob, J.; Jannuzi, B. T.; Mainzer, A.; Moustakas, L.; Rottgering, H.; Seymour, N.; Smith, H. A.; Stanford, S. A.; Stauffer, J. R.; Sullivan, I. S.; van Breugel, W.; Willner, S. P.; Wright, E. L. Abstract. We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg^2^ of the NOAO Deep Wide Field Survey Bootes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 micron bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance ({sigma}_12_) exceeds that for all sources with the same magnitude by 2{sigma}. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBootes survey, radio catalogs, 24 micron selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 micron AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of gamma ~ 0.5 at both 3.6 and 4.5 micron, and an amplitude of S_0_ ~= 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities. Key words: cosmology: observations, galaxies: active, infrared: galaxies, quasars: general
There are 497368 NED objects in this reference.
Please click here for ADS abstract

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