NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING
The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiat...
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/95451 |
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| author | Zastrow, Jordan Oey, M. S. Veilleux, Sylvain McDonald, Michael A. |
| author2 | MIT Kavli Institute for Astrophysics and Space Research |
| author_facet | MIT Kavli Institute for Astrophysics and Space Research Zastrow, Jordan Oey, M. S. Veilleux, Sylvain McDonald, Michael A. |
| author_sort | Zastrow, Jordan |
| collection | MIT |
| description | The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough ([> over ~]3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough ([< over ~]5 Myr) that the ionizing stars are still present. |
| first_indexed | 2024-09-23T08:48:36Z |
| format | Article |
| id | mit-1721.1/95451 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:48:36Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/954512022-09-23T14:40:15Z NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING Zastrow, Jordan Oey, M. S. Veilleux, Sylvain McDonald, Michael A. MIT Kavli Institute for Astrophysics and Space Research McDonald, Michael A. The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough ([> over ~]3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough ([< over ~]5 Myr) that the ionizing stars are still present. National Science Foundation (U.S.) (Grant AST-0606932) National Science Foundation (U.S.) (Grant AST-1009583) United States. National Aeronautics and Space Administration (Hubble Fellowship Grant HST-HF51308.01-A) 2015-02-20T17:29:13Z 2015-02-20T17:29:13Z 2013-11 2013-07 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/95451 Zastrow, Jordan, M. S. Oey, Sylvain Veilleux, and Michael McDonald. “NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING.” The Astrophysical Journal 779, no. 1 (December 10, 2013): 76. © 2013 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/779/1/76 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Zastrow, Jordan Oey, M. S. Veilleux, Sylvain McDonald, Michael A. NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title | NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title_full | NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title_fullStr | NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title_full_unstemmed | NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title_short | NEW CONSTRAINTS ON THE ESCAPE OF IONIZING PHOTONS FROM STARBURST GALAXIES USING IONIZATION-PARAMETER MAPPING |
| title_sort | new constraints on the escape of ionizing photons from starburst galaxies using ionization parameter mapping |
| url | http://hdl.handle.net/1721.1/95451 |
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