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Post Info TOPIC: NGC3079
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Title: Hot Ammonia in the Center of the Seyfert 2 galaxy NGC 3079
Author: Yusuke Miyamoto, Naomasa Nakai, Masumichi Seta, Dragan Salak, Kenzaburo Hagiwara, Makoto Nagai, Shun Ishii, Aya Yamauchi

We present the results of ammonia observations toward the center of NGC 3079. The NH3(J, K) = (1, 1) and (2, 2) inversion lines were detected in absorption with the Tsukuba 32-m telescope, and the NH3(1,1) through (6,6) lines with the VLA, although the profile of NH3(3,3) was in emission in contrast to the other transitions. The background continuum source, whose flux density was ~50 mJy, could not be resolved with the VLA beam of ~< 0."09 x 0."08. All ammonia absorption lines have two distinct velocity components: one is at the systemic velocity and the other is blueshifted, and both components are aligned along the nuclear jets. For the systemic components, the relatively low temperature gas is extended more than the high temperature gas. The blueshifted NH3(3,3) emission can be regarded as ammonia masers associated with shocks by strong winds probably from newly formed massive stars or supernova explosions in dense clouds in the nuclear megamaser disk. Using para-NH3(1,1), (2,2), (4,4) and (5,5) lines with VLA, we derived the rotational temperature Trot = 120 ± 12 K and 157 ± 19 K for the systemic and blueshifted components, respectively. The total column densities of NH3(0,0)-(6,6), assuming Tex ~Trot, were (8.85±0.70) x 10^16 cm^-2 and (4.47±0.78) x 10^16 cm-2 for the systemic and blueshifted components, respectively. The fractional abundance of NH3 relative to molecular hydrogen H2 for the systemic and blueshifted was [NH3]/[H2]=1.3x10^-7 and 6.5 x 10^-8, respectively. We also found the F = 4-4 and F = 5-5 doublet lines of OH 2{Pi}3/2 J = 9/2 in absorption, which could be fitted by two velocity components, systemic and redshifted components. The rotational temperature of OH was estimated to be Trot,OH >~ 175 K, tracing hot gas associated with the interaction of the fast nuclear outflow with dense molecular material around the nucleus.

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Title: AKARI infrared observations of edge-on spiral galaxy NGC 3079
Authors: Mitsuyoshi Yamagishi, Hidehiro Kaneda, Daisuke Ishihara, Shinya Komugi, Takashi Onaka, Toyoaki Suzuki

We present AKARI near- to far-infrared images of the nearby edge-on spiral galaxy NGC 3079 in 10 photometric bands. The spectral energy distribution consists of continuum emission from dust with a single temperature of 28-33 K together with strong mid-infrared emission features from polycyclic aromatic hydrocarbons (PAHs). We derive the dust masses of 5.6x10^6 M_sun and 1.4x10^7 M_sun for the central 4 kpc region and the whole galaxy, respectively, and find that a gas-to-dust mass ratio is unusually high in the central region (~ 1100) and even for the whole galaxy (~ 860). The ratio of the surface brightness distribution at the wavelength of 7 um to that at 11 um suggests that the properties of PAHs have spatial variations. Emission from ionised and neutral PAHs is relatively strong in the centre and the disk regions, respectively, suggesting stronger radiation field and thus relatively active star formation in the centre. Yet the total infrared luminosities of the galaxy indicate rather low star formation rates. These results suggest that NGC 3079 is in an early-phase starburst stage.

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Title: Green Bank Telescope observations of the water masers of NGC 3079: accretion disk magnetic field and maser scintillation
Authors: W.H.T. Vlemmings (1), H.E. Bignall (2), P.J. Diamond (1) ((1) Jodrell Bank Observatory, (2) Joint Institute for VLBI in Europe)

We present observations of the 22 GHz water megamasers in the circumnuclear disk of NGC 3079 obtained with the Green Bank Telescope. The data are analysed for circular polarisation due to the Zeeman-induced splitting of the water maser lines. No circular polarisation is detected and we derive a 1 sigma upper limit of 11 mG for the toroidal magnetic field at ~0.64 pc from the central black hole. This is the tightest upper limit for the magnetic field around a black hole to date. We use the magnetic field limit to derive an estimate of the mass accretion onto the central black hole. In addition to the polarimetric results, we present an observation of rapid variability in the maser lines, which we explain as weak interstellar scintillation. From the scintillation parameters, we estimate an intrinsic size of the mostly saturated maser features of ~12 microarcseconds. This is consistent with models assuming a thick, clumpy accretion disk.

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