A SOFIA Survey of [CII] in the galaxy M51 I. [CII] as a tracer of Star Formation
Abstract
We present a [C ii] 158 μm map of the entire M51 (including M51b) grand design spiral galaxy observed with the Far Infrared Field-Imaging Line Spectrometer (FIFI-LS) instrument on board the Stratospheric Observatory For Infrared Astronomy (SOFIA). We compare the [C ii] emission with the total far-infrared (TIR) intensity and star formation rate (SFR) surface density maps (derived using Hα and 24 μm emission) to study the relationship between [C ii] and the star formation activity in a variety of environments within M51 on scales of 16'' corresponding to ~660 pc. We find that [C ii] and the SFR surface density are well correlated in the central, spiral arm, and inter-arm regions. The correlation is in good agreement with that found for a larger sample of nearby galaxies at kpc scales. We find that the SFR, and [C ii] and TIR luminosities in M51, are dominated by the extended emission in M51's disk. The companion galaxy M51b, however, shows a deficit of [C ii] emission compared with the TIR emission and SFR surface density, with [C ii] emission detected only in the SW part of this galaxy. The [C ii] deficit is associated with an enhanced dust temperature in this galaxy. We interpret the faint [C ii] emission in M51b to be a result of suppressed star formation in this galaxy, while the bright mid- and far-infrared emission, which drive the TIR and SFR values, are powered by other mechanisms. A similar but less-pronounced effect is seen at the location of the black hole in M51's center. The observed [C ii] deficit in M51b suggests that this galaxy is a valuable laboratory to study the origin of the apparent [C ii] deficit observed in ultra-luminous galaxies.
Additional Information
© 2018 The American Astronomical Society. Received 2018 September 4; revised 2018 November 14; accepted 2018 November 15; published 2018 December 17. This research is based on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. We thank the staff of the SOFIA Science Center for their help. We also thank an anonymous referee for a number of useful comments that significantly improved the manuscript. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. © 2018. All rights reserved. U.S. Government sponsorship acknowledged. Facility: SOFIA. -Attached Files
Published - Pineda_2018_ApJL_869_L30.pdf
Accepted Version - 1811.11769.pdf
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Additional details
- Eprint ID
- 91391
- Resolver ID
- CaltechAUTHORS:20181203-093750548
- NASA
- NAS2-97001
- Deutsches Zentrum fur Luft- und Raumfahrt (DLR)
- 50 OK 0901
- NASA/JPL/Caltech
- Created
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2018-12-03Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department