Year: 1999
Type: article
Abstract: We have obtained images of the molecular hydrogen (H 2 ) and Brγ emission lines in the interacting galaxy system Arp 299. In order to investigate the nuclear activities, we also have obtained H - and K -band spectra for three of its 2 μm continuum peaks and also J -band spectra for one of them. From the line ratios of Paγ, Paβ, Br10, and Brγ, and also those between [Fe II] 1.26 μm and [Fe II] 1.64 μm, we have successfully modeled the extinction for component A as a combination of A K = 2.6 mag region(s) and A K = 0.3 mag region(s). The extinction corrected Brγ luminosity requires 5 × 10 54 s -1 of Lyman photons, which corresponds to 3 × 10 5 "O6 stars." The mean stellar density within its 100 pc core is comparable to those for the cores in blue compact dwarf galaxies even though the luminosity is almost 2 orders of magnitude larger. The starbursts at the nucleus of component A are probably the most dominant source for the far-infrared emission from this component. In this component, we have found large [Fe II]/H I ratios, which are at the higher end of starburst galaxies and are typical for AGNs or AGN/starburst composites. The nucleus must be in a starburst phase that includes many supernova remnants. The spatial distribution of the H 2 emission for this interacting system is similar to that of the 12 CO 1-0 emission mapped by Aalto et al. The H 2 intensity, however, is not proportional to the CO intensity among components, because of the difference in the H 2 excitation mechanism among them. We report the first possible detection of J -band H 2 lines in infrared luminous galaxies in component A, which suggests a significant contribution of nonthermal excitation mechanisms.
Source: The Astrophysical Journal
DOI: 10.1086/308117
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2064649502