The Spatial Structure of an Accretion Disk

Based on the microlensing variability of the two-image gravitational lens HE 1104-1805 observed between 0.4 and 8 μm, we have measured the size and wavelength-dependent structure of the quasar accretion disk. Modeled as a power law in temperature, T ∝ R−β, we measure a B-band (0.13 μm in the rest frame) half-light radius of R1/2,B = 6.7+ 6.2−3.2 × 1015 cm (68% confidence level) and a logarithmic slope of β = 0.61+ 0.21−0.17 (68% confidence level) for our standard model with a logarithmic prior on the disk size. Both the scale and the slope are consistent with simple thin disk models where β = 3/4 and R1/2,B = 5.9 × 1015 cm for a Shakura-Sunyaev disk radiating at the Eddington limit with 10% efficiency. The observed fluxes favor a slightly shallower slope, β = 0.55+ 0.03−0.02, and a significantly smaller size for β = 3/4.

[1]  Probing the Coevolution of Supermassive Black Holes and Galaxies Using Gravitationally Lensed Quasar Hosts , 2006, astro-ph/0603248.

[2]  R. Antonucci,et al.  The Nuclear Reddening Curve for Active Galactic Nuclei and the Shape of the Infrared to X-Ray Spectral Energy Distribution , 2003, astro-ph/0309595.

[3]  MEASURING THE REMNANT MASS FUNCTION OF THE GALACTIC BULGE , 1999, astro-ph/9906472.

[4]  Bradley M. Peterson,et al.  Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XIV. Intensive Optical Spectrophotometric Observations of NGC 7469 , 1998 .

[5]  Peter Schneider,et al.  Gravitational Lensing: Strong, Weak and Micro , 2006 .

[6]  V. Shalyapin,et al.  QSO size ratios from multiband monitoring of a microlensing high-magnification event , 2004, astro-ph/0406558.

[7]  Jeffrey D. Scargle,et al.  Statistical challenges in modern astronomy II , 1997 .

[8]  C. Kochanek.  Quantitative Interpretation of Quasar Microlensing Light Curves , 2003, astro-ph/0307422.

[9]  P. Schechter,et al.  Size Is Everything: Universal Features of Quasar Microlensing with Extended Sources , 2004, astro-ph/0408195.

[10]  J. Hjorth,et al.  Detection of the lensing galaxy for the double QSO HE 1104-1805 , 1998 .

[11]  E. Agol,et al.  Imaging a Quasar Accretion Disk with Microlensing , 1999, astro-ph/9905111.

[12]  P. Schechter,et al.  X-Ray and Optical Flux Ratio Anomalies in Quadruply Lensed Quasars. I. Zooming in on Quasar Emission Regions , 2006, astro-ph/0607655.

[13]  Albert A. Harrison.  Confirmation of ETI: initial organizational response , 2003 .

[14]  M. Wolff,et al.  A Quantitative Comparison of the Small Magellanic Cloud, Large Magellanic Cloud, and Milky Way Ultraviolet to Near-Infrared Extinction Curves , 2003 .

[15]  J. Lehár,et al.  Hubble Space Telescope Observations of 10 Two-Image Gravitational Lenses , 1999 .

[16]  E. Turner,et al.  The distribution of microlensed light-curve derivatives: the relationship between stellar proper motions and transverse velocity , 1999, astro-ph/9901339.

[17]  C. Kochanek,et al.  Mid-IR Observations and a Revised Time Delay for the Gravitational Lens System Quasar HE 1104–1805 , 2006, astro-ph/0612045.

[18]  P. Schechter,et al.  Microlensing of Relativistic Knots in the Quasar HE 1104–1805 AB , 2002, astro-ph/0206263.

[19]  L. Wisotzki,et al.  The Double Quasar HE 1104–1805: A case study for time delay determination with poorly sampled lightcurves , 2002 .

[20]  E. Agol,et al.  Non-LTE Models and Theoretical Spectra of Accretion Disks in Active Galactic Nuclei. IV. Effects of Compton Scattering and Metal Opacities , 2001, astro-ph/0105507.

[21]  C. Keeton,et al.  Microlensing of an extended source by a power-law mass distribution , 2006, astro-ph/0612542.

[22]  P. Jetzer.  Gravitational Microlensing , 1999, Naturwissenschaften.

[23]  L.Wisotzki,et al.  The Double Quasar HE1104-1805: a case study for time delay determination with poorly sampled lightcurves , 2001, astro-ph/0111075.

[24]  Time-Delay Measurement of the Lensed Quasar HE 1104-1805 , 2003, astro-ph/0305200.

[25]  Bradley M. Peterson,et al.  A NEW DIRECT METHOD FOR MEASURING THE HUBBLE CONSTANT FROM REVERBERATING ACCRETION DISCS IN ACTIVE GALAXIES , 1999 .

[26]  S. G. Sergeev,et al.  Lag-Luminosity Relationship for Interband Lags between Variations in B, V, R, and I Bands in Active Galactic Nuclei , 2005 .