ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

• Published in: The Astrophysical journal 2015-09, Vol.811 (1), p.1-15
• Main Authors: Izumi, Takuma, Kohno, Kotaro, Aalto, Susanne, Doi, Akihiro, Espada, Daniel, Fathi, Kambiz, Harada, Nanase, Hatsukade, Bunyo, Hattori, Takashi, Hsieh, Pei-Ying, Ikarashi, Soh, Imanishi, Masatoshi, Iono, Daisuke, Ishizuki, Sumio, Krips, Melanie, Martín, Sergio, Matsushita, Satoki, Meier, David S., Nagai, Hiroshi, Nakai, Naomasa, Nakajima, Taku, Nakanishi, Kouichiro, Nomura, Hideko, Regan, Michael W., Schinnerer, Eva, Sheth, Kartik, Takano, Shuro, Tamura, Yoichi, Terashima, Yuichi, Tosaki, Tomoka, Turner, Jean L., Umehata, Hideki, Wiklind, Tommy
• Format: Article
• Language: English
• Subjects: 1995; Active galactic nuclei; agn-driven outflow; Arrays; Astronomy & Astrophysics; astrophysical journal; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; broad-line region; CARBON MONOXIDE; CHEMICAL COMPOSITION; cloverleaf quasar; COMPARATIVE EVALUATIONS; Continuums; galactic; galaxies: active; galaxies: individual (NGC 7469); galaxies: ISM; GALAXY NUCLEI; HEATING; HYDROCYANIC ACID; infrared galaxies; ISM: molecules; JETS; LUMINOSITY; MOLECULES; nearby; nuclei; nzel r; p129; photon-dominated regions; PROBES; Radio telescopes; RESOLUTION; SEYFERT GALAXIES; SPATIAL DISTRIBUTION; STAR CLUSTERS; star-formation; STARS; supermassive black-hole; Tracers; v444; X RADIATION; x-ray; X-rays
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.1088/0004-637X/811/1/39

ABSTRACT We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0 5 ×0 4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4-3), HCO+(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860 m continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1 5-2 5. Several structures connect these components. Except for CO(3-2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4-3)/HCO+(4-3) and HCN(4-3)/CS(7-6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4-3)/HCO+(4-3) ratio at the AGN position of NGC 7469 (1.11 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.