artículo
Infrared polarimetry of Mrk 231: scattering off hot dust grains in the central core
Fecha
2017Registro en:
10.1093/mnras/stw2491
1365-2966
0035-8711
WOS:000393647100038
Autor
Lopez Rodriguez, E.
Packham, C.
Jones, T. J.
Siebenmorgen, R.
Roche, P. F.
Levenson, N. A.
Alonso Herrero, A.
Perlman, E.
Ichikawa, K.
Ramos Almeida, C.
Gonzalez Martin, O.
Nikutta, R.
Martinez Paredez, M.
Shenoy, D.
Gordon, M. S.
Telesco, C. M.
Institución
Resumen
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, 10.3, 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 +/- 4 K) dusty structure, directly irradiated by the central engine, which is at 1.6 +/- 0.1 pc away and attributed to be in the pc-scale polar region, (2) an optically-thick, smooth and disc-like dusty structure ('torus') with an inclination of 48 degrees +/- 23 degrees surrounding the central engine, and (3) an extinguished (A(V) = 36 +/- 5 mag) starburst component. The polarized SED decreases from 0.77 +/- 0.14 per cent at 1.2 mu m to 0.31 +/- 0.15 per cent at 11.6 mu m and follows a power-law function, lambda(similar to 0.57). The polarization angle remains constant (similar to 108 degrees) 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.