http://arxiv.org/abs/1606.03582
We present new mid-IR observations of the quadruply lensed quasar Q 2237+0305 taken with CanariCam on the Gran Telescopio Canarias (GTC). Mid-IR emission by hot dust, unlike the optical and near-IR emission from the accretion disk, is unaffected by the ISM (extinction/scattering) or stellar microlensing. We compare these “true” ratios to the (stellar) microlensed flux ratios observed in the optical/near-IR to constrain the structure of the quasar accretion disk. We find a half-light radius of $R_{1/2}=3.4_{-2.1}^{+5.3}\sqrt{\langle M \rangle/0.3M_\odot}$ light-days at $\lambda_{rest}=1736$ \AA, and an exponent for the temperature profile $R \propto \lambda^{p}$ of $p=0.79\pm0.55$ where $p=4/3$ for a standard thin disk model. We find a lower limit for the size of the mid-IR emitting region of $R_{1/2} \gtrsim 200\,\sqrt{\langle M \rangle/0.3M_\odot}$ light-days. We also test for the presence of substructure/satellites by comparing the observed mid-IR flux ratios with those predicted from smooth lens models. We can explain the differences if the surface density fraction in satellites near the lensed images is $\alpha = 0.033_{-0.019}^{+0.046}$ for a singular isothermal ellipsoid plus external shear mass model or $\alpha = 0.013_{-0.008}^{+0.019}$ for a mass model combining ellipsoidal NFW and de Vaucouleurs profiles in an external shear.
H. Vives-Arias, J. Munoz, C. Kochanek, et. al.
Tue, 14 Jun 16
45/67
Comments: 17 pages, 3 figures, 2 tables; submitted to ApJ
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