The Interstellar Medium and Star Formation in Edge-On Galaxies. II. NGC 4157, 4565, and 5907
Abstract
We present a study of the vertical structure of the gaseous and stellar disks in a sample of edge-on galaxies (NGC 4157, 4565, and 5907) using BIMA/CARMA ^(12)CO J = 1 → 0, VLA HI, and Spitzer 3.6 μm data. In order to take into account projection effects when we measure the disk thickness as a function of radius, we first obtain the inclination by modeling the radio data. Using the measurement of the disk thicknesses and the derived radial profiles of gas and stars, we estimate the corresponding volume densities and vertical velocity dispersions. Both stellar and gas disks have smoothly varying scale heights and velocity dispersions, contrary to assumptions of previous studies. Using the velocity dispersions, we find that the gravitational instability parameter Q follows a fairly uniform profile with radius and is ⩾1 across the star-forming disk. The star formation law has a slope that is significantly different from those found in more face-on galaxy studies, both in deprojected and pixel-by-pixel plots. Midplane gas pressure based on the varying scale heights and velocity dispersions appears to roughly hold a power-law correlation with the midplane volume density ratio.
Additional Information
© 2014 American Astronomical Society. Received 2013 November 8; accepted 2014 August 9; published 2014 November 11. We thank the anonymous referee for useful comments and suggestions that improved this paper. K.Y. thanks Laura Zschaechner and Gyula Józsa for help with using TiRiFiC. This study is supported by the National Science Foundation under cooperative agreements AST-0838226 and AST-1139950 and by a Spitzer Cycle-5 data analysis award from NASA. Support for CARMA construction was derived from the states of California, Illinois, and Maryland, the James S. McDonnell Foundation, the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the University of Chicago, the Associates of the California Institute of Technology, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement, and by the CARMA partner universities. K.Y. and J.M.H. acknowledge support from the European Research Council under the European Unionʼs Seventh Framework Programme (FP/2007–2013) / ERC Grant Agreement No. 291531. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.Attached Files
Published - 1538-3881_148_6_127.pdf
Submitted - 1408.5905v1.pdf
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Additional details
- Eprint ID
- 53042
- Resolver ID
- CaltechAUTHORS:20141219-112453046
- AST-0838226
- NSF
- AST-1139950
- NSF
- NASA Spitzer Cycle-5 data analysis award
- State of California
- James S. McDonnell Foundation
- Gordon and Betty Moore Foundation
- Kenneth T. and Eileen L. Norris Foundation
- University of Chicago
- Caltech Associates
- NSF
- Caltech
- 291531
- European Research Council (ERC)
- State of Illinois
- State of Maryland
- University of California Berkeley
- University of Illinois, Urbana -Champaign
- University of Maryland
- Created
-
2014-12-19Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field