Infrared polarimetry of Mrk 231: Scattering off hot dust grains in the central core
| Autor: | Lopez-Rodriguez, E., Packham, C., Jones, T. J., Siebenmorgen, R., Roche, P. F., Levenson, N. A., Alonso-Herrero, A., Perlman, E., Ichikawa, K., Almeida, C. Ramos, Gonzalez-Martin, O., Nikutta, R., Martinez-Paredes, M., Shenoy, D., Gordon, M. S., Telesco, C. M. |
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| Rok vydání: | 2016 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stw2491 |
| Popis: | We present high-angular (0.17$-$0.35 arcsec) resolution imaging polarimetric observations of Mrk 231 in the 3.1 $\mu$m filter using MMT-Pol on the 6.5-m MMT, and in the 8.7 $\mu$m, 10.3 $\mu$m, and 11.6 $\mu$m filters using CanariCam on the 10.4-m Gran Telescopio CANARIAS. In combination with already published observations, we compile the 1$-$12 $\mu$m total and polarized nuclear spectral energy distribution (SED). The total flux SED in the central 400 pc is explained as the combination of 1) a hot (731 $\pm$ 4 K) dusty structure, directly irradiated by the central engine, which is at 1.6 $\pm$ 0.1 pc away and attributed to be in the pc-scale polar region, 2) an optically-thick, smooth and disk-like dusty structure (`torus') with an inclination of 48 $\pm$ 23$^{\circ}$ surrounding the central engine, and 3) an extinguished (A$_{\mbox{V}} =$ 36 $\pm$ 5 mag) starburst component. The polarized SED decreases from 0.77 $\pm$ 0.14 per cent at 1.2 $\mu$m to 0.31 $\pm$ 0.15 per cent at 11.6 $\mu$m and follows a power-law function, $\lambda^{\sim0.57}$. The polarization angle remains constant ($\sim$108$^{\circ}$) in the 1$-$12 $\mu$m wavelength range. The dominant polarization mechanism is explained as scattering off hot dust grains in the pc-scale polar regions. Comment: 9 pages, 2 figures. Accepted for publication in MNRAS |
| Databáze: | arXiv |
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