Spitzer observations of a gravitationally lensed quasar, QSO 2237+0305

Abstract

The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infrared Array Camera (IRAC) observations of QSO 2237+0305, finding the following. (1) The infrared (IR) spectral energy distribution (SED) is similar to that of other bright radio-quiet quasars, contrary to an earlier claim. (2) A dusty torus model with a small opening angle fits the overall shape of the IR SED well, but the quantitative agreement is poor due to an offset in wavelength of the silicate feature. (3) The flux ratios of the four lensed images can be derived from the IRAC data despite being unresolved. We find that the near-IR fluxes are increasingly affected by microlensing toward shorter wavelengths. (4) The wavelength dependence of the IRAC flux ratios is consistent with the standard quasar model in which an accretion disk and a dusty torus both contribute near 1 micron in the rest frame. This is also consistent with recent IR spectropolarimetry of nearby quasars.

References in corpus (8)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Spitzer Quasar and ULIRG Evolution Study (QUEST): II. The Spectral Energy Distributions of Palomar-Green Quasars
• The Spatial Structure of An Accretion Disk
• The characteristic blue spectra of accretion disks in quasars as uncovered in the infrared
• Microlensing variability in the gravitationally lensed quasar QSO 2237+0305 = the Einstein Cross. II. Energy profile of the accretion disk
• The multiple quasar Q2237+0305 under a microlensing caustic
• Microlensing variability in the gravitationally lensed quasar Q2237+0305 = the Einstein Cross, I. Spectrophotometric monitoring with the VLT
• The Optical Gravitational Lensing Experiment. OGLE-III Long Term Monitoring of the Gravitational Lens QSO 2237+0305

Cited by in corpus (22)

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• Microlensing of the broad line region in 17 lensed quasars
• The Structure of the X-ray and Optical Emitting Regions of the Lensed Quasar Q 2237+0305
• A Robust Determination of the size of quasar accretion disks using gravitational microlensing
• The Average Size and Temperature Profile of Quasar Accretion Disks
• Microlensing Evidence That A Type 1 Quasar Is Viewed Face On
• The Transverse Peculiar Velocity of the Q2237+0305 Lens Galaxy and the Mean Mass of Its Stars
• X-ray Monitoring of Gravitational Lenses With Chandra
• Detection of Substructure in the Gravitationally Lensed Quasar MG0414+0534 using Mid-Infrared and Radio VLBI Observations
• Zooming into the broad line region of the gravitationally lensed quasar Q2237+0305 = the Einstein Cross: III. Determination of the size and structure of the CIV and CIII] emitting regions using microlensing
• Discovery of Energy Dependent X-ray Microlensing in Q2237+0305
• The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN
• Near-Infrared K and L' Flux Ratios in Six Lensed Quasars
• Mid-infrared microlensing of accretion disc and dusty torus in quasars: effects on flux ratio anomalies
• Gravitational microlensing of AGN dusty tori
• X-ray microlensing in the quadruply lensed quasar Q2237+0305
• Observations of the Lensed Quasar Q2237+0305 with CanariCam at GTC
• Super-Eddington accretion in the Q2237+0305 quasar?
• Gravitational Microlensing as a probe of the Electron Scattering Region in Q2237+0305