Hot ammonia in the center of the Seyfert 2 galaxy NGC 3079

• Published in: Publications of the Astronomical Society of Japan Vol. 67; no. 1
• Main Authors: Miyamoto, Yusuke, Nakai, Naomasa, Seta, Masumichi, Salak, Dragan, Hagiwara, Kenzaburo, Nagai, Makoto, Ishii, Shun, Yamauchi, Aya
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.02.2015
• Subjects: galaxies: individual (NGC 3079); radio lines: galaxies; radio lines: ISM; galaxies: ISM
• ISSN: 0004-6264; 0004-6264; 2053-051X
• DOI: 10.1093/pasj/psu131

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 ${^{\prime\prime}_{.}}$ 09 × 0 ${^{\prime\prime}_{.}}$ 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 T rot = 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 T ex ≈ T rot, were (8.85 ± 0.70) × 1016 cm−2 and (4.47 ± 0.78) × 1016 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] = 1.3 × 10−7 and 6.5 × 10−8, respectively. We also found the F = 4–4 and F = 5–5 doublet lines of OH 2Π3/2 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 T rot, OH ≥ 175 K, tracing hot gas associated with the interaction of the fast nuclear outflow with dense molecular material around the nucleus.