2024-03-29T06:41:00Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1830052023-01-03T11:08:18Zcom_10261_89com_10261_3com_10261_97com_10261_4col_10261_342col_10261_350
2019-05-31T09:03:40Z
urn:hdl:10261/183005
Probing highly obscured, self-absorbed galaxy nuclei with vibrationally excited HCN
Aalto, S.
Martin, S.
Costagliola, Francesco
González-Alfonso, E.
Müller, S.
Sakamoto, K.
Fuller, G. A.
García-Burillo, S.
Van Der Werf, P.
Neri, Roberto
Spaans, M.
Combes, F.
Viti, S.
Mühle, S.
Armus, L.
Evans, A.
Sturm, E.
Cernicharo, José
Henkel, C.
Greve, T. R.
ISM: molecules
Galaxies: ISM
Galaxies: nuclei
Galaxies: active
Galaxies: evolution
We present high resolution (0.̋4) IRAM PdBI and ALMA mm and submm observations of the (ultra) luminous infrared galaxies ((U)LIRGs) IRAS 17208-0014, Arp220, IC 860 and Zw049.057 that reveal intense line emission from vibrationally excited (ν2 = 1) J = 3–2 and 4–3 HCN. The emission is emerging from buried, compact (r< 17–70 pc) nuclei that have very high implied mid-infrared surface brightness > 5 × 1013 L⊙ kpc-2. These nuclei are likely powered by accreting supermassive black holes (SMBHs) and/or hot (>200 K) extreme starbursts. Vibrational, ν2 = 1, lines of HCN are excited by intense 14 μm mid-infrared emission and are excellent probes of the dynamics, masses, and physical conditions of (U)LIRG nuclei when H2 column densities exceed 1024 cm-2. It is clear that these lines open up a new interesting avenue to gain access to the most obscured AGNs and starbursts. Vibrationally excited HCN acts as a proxy for the absorbed mid-infrared emission from the embedded nuclei, which allows for reconstruction of the intrinsic, hotter dust SED. In contrast, we show strong evidence that the ground vibrational state (ν = 0), J = 3–2and 4–3 rotational lines of HCN and HCO+ fail to probe the highly enshrouded, compact nuclear regions owing to strong self- and continuum absorption. The HCN and HCO+ line profiles are double-peaked because of the absorption and show evidence of non-circular motions – possibly in the form of in- or outflows. Detections of vibrationally excited HCN in external galaxies are so far limited to ULIRGs and early-type spiral LIRGs, and we discuss possible causes for this. We tentatively suggest that the peak of vibrationally excited HCN emission is connected to a rapid stage of nuclear growth, before the phase of strong feedback.
2019-05-31T09:03:40Z
2019-05-31T09:03:40Z
2015-11-18
2019-05-31T09:03:40Z
artículo
Astronomy and Astrophysics 584: A42 (2015)
http://hdl.handle.net/10261/183005
10.1051/0004-6361/201526410
eng
Publisher's version
https://doi.org/10.1051/0004-6361/201526410
Sí
openAccess
EDP Sciences