Browsing by Author "Nikutta, R."

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    Infrared polarimetry of Mrk 231: scattering off hot dust grains in the central core
    (OXFORD UNIV PRESS, 2017) 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.
    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.
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    Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068
    (2016) Lopez-Rodriguez, E.; Packham, C.; Roche, P. F.; Alonso-Herrero, A.; Díaz-Santos, T.; Nikutta, R.; González-Martín, O.; Á lvarez, C. A.; Esquej, P.; Espinos, J. M. R.; Perlman, E.; Ramos Almeida, C.; Telesc, C. M.
    We present subarcsecond 7.5–13 μm imaging- and spectro-polarimetric observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio CANARIAS. At all wavelengths, we find: (1) A 90 × 60 pc extended polarized feature in the northern ionization cone, with a uniform ∼44$^\circ$ polarization angle. Its polarization arises from dust and gas emission in the ionization cone, heated by the active nucleus and jet, and further extinguished by aligned dust grains in the host galaxy. The polarization spectrum of the jet–molecular cloud interaction at ∼24 pc from the core is highly polarized, and does not show a silicate feature, suggesting that the dust grains are different from those in the interstellar medium. (2) A southern polarized feature at ∼9.6 pc from the core. Its polarization arises from a dust emission component extinguished by a large concentration of dust in the galaxy disc. We cannot distinguish between dust emission from magnetically aligned dust grains directly heated by the jet close to the core, and aligned dust grains in the dusty obscuring material surrounding the central engine. Silicate-like grains reproduce the polarized dust emission in this feature, suggesting different dust compositions in both ionization cones. (3) An upper limit of polarization degree of 0.3 per cent in the core. Based on our polarization model, the expected polarization of the obscuring dusty material is ≲0.1 per cent in the 8–13 μm wavelength range. This low polarization may be arising from the passage of radiation through aligned dust grains in the shielded edges of the clumps.
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    New ATCA, ALMA and VISIR observations of the candidate LBV SK-67 266 (S61): The nebular mass from modelling 3D density distributions
    (2017) Agliozzo, C.; Nikutta, R.; Pignata, Giuliano; Phillips, N. M.; Ingallinera, A.; Buemi, C.; Umana, G.; Leto, P.; Trigilio, C.; Noriega-Crespo, A.; Paladini, R.; Bufano, F.; Cavallaro, F.
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    NuSTAR Observations of WISE J1036+0449, a Galaxy at z~1 Obscured by Hot Dust.
    (2017) Ricci, Claudio; Bauer, Franz Erik; Treister, Ezequiel; Nikutta, R.; Assef T., Roberto; Stern, D.; Alexander, D. M.; Asmus, D.; Ballantyne, D. R.; Blain, A. W.; Boggs, Steven E.
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    The Luminous Blue Variable RMC 127 as Seen with ALMA and ATCA
    (2017) Agliozzo, C.; Trigilio, C.; Pignata, Giuliano; Phillips, N. M.; Nikutta, R.; Leto, P.; Umana, G.; Ingallinera, A.; Buemi, C.; Bauer, Franz Erik