Quasar Variability in the Mid-Infrared

Abstract

The Decadal IRAC Bootes Survey is a mid-IR variability survey of the ~9 sq. deg. of the NDWFS Bootes Field and extends the time baseline of its predecessor, the Spitzer Deep, Wide-Field Survey (SDWFS), from 4 to 10 years. The Spitzer Space Telescope visited the field five times between 2004 and 2014 at 3.6 and 4.5 microns. We provide the difference image analysis photometry for a half a million mostly extragalactic sources. In mid-IR color-color plane, sources with quasar colors constitute the largest variability class (75%), 16% of the variable objects have stellar colors and the remaining 9% have the colors of galaxies. Adding the fifth epoch doubles the number of variable active galactic nuclei (AGNs) for the same false positive rates as in SDWFS, or increases the number of sources by 20% while decreasing the false positive rates by factors of 2-3 for the same variability amplitude. We quantify the ensemble mid-IR variability of ~1500 spectroscopically confirmed AGNs using single power-law structure functions (SFs), which we find to be steeper (index $\gamma =0.45$) than in the optical ($\gamma =0.3$), leading to much lower amplitudes at short time-lags. This provides evidence for large emission regions, smoothing out any fast UV/optical variations, as the origin of infrared quasar variability. The mid-IR AGN SF slope $\gamma$ seems to be uncorrelated with both the luminosity and rest-frame wavelength, while the amplitude shows an anti-correlation with the luminosity and a correlation with the rest-frame wavelength.

published in ApJ

References in corpus (19)

• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Direct cosmological simulations of the growth of black holes and galaxies
• Is Quasar Optical Variability a Damped Random Walk?
• A systematic search for close supermassive black hole binaries in the Catalina Real-Time Transient Survey
• Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
• The Spitzer Deep, Wide-Field Survey
• Spitzer's Contribution to the AGN Population
• Half of the Most Luminous Quasars May Be Obscured: Investigating the Nature of WISE-Selected Hot, Dust-Obscured Galaxies
• Space Telescope and Optical Reverberation Mapping Project. I. Ultraviolet Observations of the Seyfert 1 Galaxy NGC 5548 with the Cosmic Origins Spectrograph on Hubble Space Telescope
• Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?
• A large population of mid-infrared selected, obscured active galaxies in the Bootes field
• The multiwavelength variability of 3C 273
• Quasar Selection Based on Photometric Variability
• Mid-Infrared Variability from the Spitzer Deep, Wide-Field Survey
• Discovery of 5000 Active Galactic Nuclei behind the Magellanic Clouds
• The Mid-Infrared Properties of X-ray Sources
• Spitzer Space Telescope Measurements of Dust Reverberation Lags in the Seyfert 1 Galaxy NGC 6418
• The QUEST-La Silla AGN Variability Survey
• Molecular Gas and Star Formation in the Cartwheel

Cited by in corpus (32)

• Active Galactic Nuclei: what's in a name?
• Revisiting Stochastic Variability of AGNs with Structure Functions
• A possible mechanism for multiple changing look phenomenon in Active Galactic Nuclei
• Improving Damped Random Walk parameters for SDSS Stripe 82 Quasars with Pan-STARRS1
• WALLABY Early Science - III. An HI Study of the Spiral Galaxy NGC 1566
• AT 2017gbl: a dust obscured TDE candidate in a luminous infrared galaxy
• How far is quasar UV/optical variability from damped random walk at low frequency?
• Dust Reverberation Mapping in Distant Quasars from Optical and Mid-Infrared Imaging Surveys
• Infrared Spectral Energy Distribution and Variability of Active Galactic Nuclei: Clues to the Structure of Circumnuclear Material
• The Chandra Deep Wide-Field Survey: A New Chandra Legacy Survey in the Boötes Field I. X-ray Point Source Catalog, Number Counts and Multi-Wavelength Counterparts
• A Luminous Transient Event in a Sample of WISE-Selected Variable AGN
• The Past and Future of Mid-Infrared Studies of AGN
• WISE view of Narrow-Line Seyfert 1 galaxies: mid-infrared color and variability
• A Method to Measure the Unbiased Decorrelation Timescale of the AGN Variable Signal from Structure Functions
• A Low Incidence of Mid-Infrared Variability in Dwarf Galaxies
• Spitzer Photometry of ~1 Million Stars in M31 and 15 Other Galaxies
• Modeling the Variability of Active Galactic Nuclei by Infinite Mixture of Ornstein-Uhlenbeck(OU) Processes
• Constraining AGN Torus Sizes with Optical and Mid-Infrared Ensemble Structure Functions
• Mid-infrared Variability of gamma-ray emitting blazars
• Modeling changing-look (CL) AGN phenomenon in 1D using accretion disk instabilities
• Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift
• Black hole virial masses from single-epoch photometry: the miniJPAS test case
• An interacting galaxy pair at the origin of a light echo
• The mid-infrared variability of the SDSS optical quasars
• Infrared variable stars in the compact elliptical galaxy M32
• A Complete 16 micron-Selected Galaxy Sample at $z\sim 1$: Mid-infrared Spectral Energy Distributions
• Quantifying the Active Galactic Nuclei Fraction in Cosmic Voids via Mid-Infrared Variability
• Discovery of two quasars at $z=5$ from the OGLE Survey
• Long-term Mid-infrared Color Variations of Narrow-Line Seyfert 1 Galaxies
• Variability Selected Active Galactic Nuclei from ASAS-SN Survey: Constraining the Low Luminosity AGN Population
• Identification of quasars variable over long time scales from infrared surveys. Ensemble variability and structure function properties
• Empirical Conversions of Broad-Band Optical and Infrared Magnitudes to Monochromatic Continuum Luminosities for Active Galactic Nuclei