H i Kinematics along the Minor Axis of M82
Journal Article
·
· The Astrophysical Journal (Online)
- The Ohio State Univ., Columbus, OH (United States); DOE/OSTI
- The Ohio State Univ., Columbus, OH (United States)
- National Radio Astronomy Observatory, Charlottesville, VA (United States)
- Univ. of Maryland, College Park, MD (United States)
- Rincon Research Corp., Tucson, AZ (United States)
- Univ. of California, San Diego, CA (United States)
- Max Planck Inst. für Astronomie, Heidelberg (Germany)
M82 is one of the best-studied starburst galaxies in the local universe, and is consequently a benchmark for researching star formation feedback at both low and high redshift. We introduce new VLA H i observations that reveal the cold gas kinematics along the minor axis in unprecedented detail. This includes the detection of H i up to 10 kpc along the minor axis toward the south and beyond 5 kpc to the north. A surprising aspect of these observations is that the line-of-sight H i velocity decreases substantially from about 120 to $$50\,\mathrm{km}\,{{\rm{s}}}^{-1}$$ from 1.5 to 10 kpc off the midplane. The velocity profile is not consistent with the H i gas cooling from the hot wind. We determine that the velocity decrease is substantially greater than the deceleration expected from gravitational forces alone. If the H i consists of a continuous population of cold clouds, some additional drag force must be present, and the magnitude of the drag force places a joint constraint on the ratio of the ambient medium to the typical cloud size and density. We also demonstrate that the H i kinematics are inconsistent with a simple conical outflow centered on the nucleus, but instead require the more widespread launch of the H i over the ~1 kpc extent of the starburst region. Regardless of the launch mechanism for the H i gas, the observed velocity decrease along the minor axis is sufficiently great that the H i may not escape the halo of M82. The inferred H i outflow rate at 10 kpc off the midplane is much less than 1 $${M}_{\odot }$$ yr–1.
- Research Organization:
- The Ohio State Univ., Columbus, OH (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
- Grant/Contract Number:
- SC0015525
- OSTI ID:
- 1542019
- Journal Information:
- The Astrophysical Journal (Online), Journal Name: The Astrophysical Journal (Online) Journal Issue: 1 Vol. 856; ISSN 1538-4357
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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