Cold molecular gas and PAH emission in the nuclear and circumnuclear regions of Seyfert galaxies

Autor: Ric Davies, Dimitra Rigopoulou, Patrick F. Roche, I. García-Bernete, Donaji Esparza-Arredondo, Francoise Combes, Sebastian F. Hönig, A. J. Domínguez-Fernández, A. Alonso-Herrero, Omaira González-Martín, Santiago García-Burillo, E. K. S. Hicks, N. A. Levenson, C. Ramos Almeida, David J. Rosario, Miguel Pereira-Santaella, Antonio Hernán-Caballero, Tanio Díaz-Santos
Přispěvatelé: Agencia Estatal de Investigación (AEI), Comunidad de Madrid, Science and Technology Facilities Council (STFC), Universidad Nacional Autónoma de México (UNAM), European Research Council (ERC), National Aeronautics and Space Administration (NASA), Almeida, C. R. [0000-0001-8353-649X], Díaz Santos, T. [0000-0003-0699-6083], Rosario, D. [0000-0002-0001-3587], Roche, P. [0000-0002-8524-8413], Davies, R. [0000-0003-4949-7217], Hoening, S. [0000-0002-6353-1111], MCIU/AEI/FEDER, UE, Comunidad de Madrid, 2018-T1/TIC-11035UE PGC2018094671-B-I00 AYA201676682-C3-2-P, Science & Technology Facilities Council (STFC), UNAM PAPIIT project, EU Horizon 2020 framework program via the ERC Starting Grant DUST-INTHE-WIND, Spanish Ministry of Science Innovation and Universities, National Aeronautics & Space Administration (NASA), University of Oxford John Fell Fund, Unidad de Excelencia María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC
Rok vydání: 2020
Předmět:
Zdroj: DIGITAL.INTA Repositorio Digital del Instituto Nacional de Técnica Aeroespacial
instname
Instituto Nacional de Técnica Aeroespacial (INTA)
Digital.CSIC. Repositorio Institucional del CSIC
Astronomy & Astrophysics
Popis: We investigate the relation between the detection of the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature in the nuclear (∼24-230 pc) regions of 22 nearby Seyfert galaxies and the properties of the cold molecular gas. For the former we use ground-based (0.3-0.6″ resolution) mid-infrared (mid-IR) spectroscopy. The cold molecular gas is traced by ALMA and NOEMA high (0.2-1.1″) angular resolution observations of the CO(2-1) transition. Galaxies with a nuclear detection of the 11.3 μm PAH feature contain more cold molecular gas (median 1.6 × 107 MO ) and have higher column densities (N(H2) = 2 × 1023 cm-2) over the regions sampled by the mid-IR slits than those without a detection. This suggests that molecular gas plays a role in shielding the PAH molecules in the harsh environments of Seyfert nuclei. Choosing the PAH molecule naphthalene as an illustration, we compute its half-life in the nuclear regions of our sample when exposed to 2.5 keV hard X-ray photons. We estimate shorter half-lives for naphthalene in nuclei without a 11.3 μm PAH detection than in those with a detection. The Spitzer/IRS PAH ratios on circumnuclear scales (∼4″ ∼ 0.25-1.3 kpc) are in between model predictions for neutral and partly ionized PAHs. However, Seyfert galaxies in our sample with the highest nuclear H2 column densities are not generally closer to the neutral PAH tracks. This is because in the majority of our sample galaxies, the CO(2-1) emission in the inner ∼4″ is not centrally peaked and in some galaxies traces circumnuclear sites of strong star formation activity. Spatially resolved observations with the MIRI medium-resolution spectrograph on the James Webb Space Telescope will be able to distinguish the effects of an active galactic nucleus (AGN) and star formation on the PAH emission in nearby AGN.
With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)
Databáze: OpenAIRE
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