Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy
We report the serendipitous detection of a 0.2 L*, Lyα emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background QSO sightline. A high-resolution spectrum of the QSO reveals a partial Lyman-limit absorption system (N[subscript Hi] = 10[superscript 16.94±0.10] cm[super...
| Main Authors: | , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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Oxford University Press
2015
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| Online Access: | http://hdl.handle.net/1721.1/98292 https://orcid.org/0000-0003-3769-9559 |
| _version_ | 1811090855354695680 |
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| author | Crighton, Neil H. M. Hennawi, Joseph F. Simcoe, Robert A. Cooksey, Kathy L. Murphy, Michael T. Fumagalli, Michele Prochaska, J. Xavier Shanks, Tom |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Crighton, Neil H. M. Hennawi, Joseph F. Simcoe, Robert A. Cooksey, Kathy L. Murphy, Michael T. Fumagalli, Michele Prochaska, J. Xavier Shanks, Tom |
| author_sort | Crighton, Neil H. M. |
| collection | MIT |
| description | We report the serendipitous detection of a 0.2 L*, Lyα emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background QSO sightline. A high-resolution spectrum of the QSO reveals a partial Lyman-limit absorption system (N[subscript Hi] = 10[superscript 16.94±0.10] cm[superscript −2]) with many associated metal absorption lines at the same redshift as the foreground galaxy. Using photoionization models that carefully treat measurement errors and marginalize over uncertainties in the shape and normalization of the ionizing radiation spectrum, we derive the total hydrogen column density N[subscript H] = 10[superscript 19.4±0.3] cm[superscript −2], and show that all the absorbing clouds are metal enriched, with Z = 0.1–0.6 Z[subscript ⊙]. These metallicities and the system's large velocity width (436 km s[superscript −1]) suggest the gas is produced by an outflowing wind. Using an expanding shell model we estimate a mass outflow rate of ~5 M[subscript ⊙] yr[superscript −1]. Our photoionization model yields extremely small sizes (<100–500 pc) for the absorbing clouds, which we argue is typical of high column density absorbers in the circumgalactic medium (CGM). Given these small sizes and extreme kinematics, it is unclear how the clumps survive in the CGM without being destroyed by hydrodynamic instabilities. The small cloud sizes imply that even state-of-the-art cosmological simulations require more than a 1000-fold improvement in mass resolution to resolve the hydrodynamics relevant for cool gas in the CGM. |
| first_indexed | 2024-09-23T14:53:02Z |
| format | Article |
| id | mit-1721.1/98292 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:53:02Z |
| publishDate | 2015 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | mit-1721.1/982922022-10-01T23:07:27Z Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy Crighton, Neil H. M. Hennawi, Joseph F. Simcoe, Robert A. Cooksey, Kathy L. Murphy, Michael T. Fumagalli, Michele Prochaska, J. Xavier Shanks, Tom Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Simcoe, Robert A. We report the serendipitous detection of a 0.2 L*, Lyα emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background QSO sightline. A high-resolution spectrum of the QSO reveals a partial Lyman-limit absorption system (N[subscript Hi] = 10[superscript 16.94±0.10] cm[superscript −2]) with many associated metal absorption lines at the same redshift as the foreground galaxy. Using photoionization models that carefully treat measurement errors and marginalize over uncertainties in the shape and normalization of the ionizing radiation spectrum, we derive the total hydrogen column density N[subscript H] = 10[superscript 19.4±0.3] cm[superscript −2], and show that all the absorbing clouds are metal enriched, with Z = 0.1–0.6 Z[subscript ⊙]. These metallicities and the system's large velocity width (436 km s[superscript −1]) suggest the gas is produced by an outflowing wind. Using an expanding shell model we estimate a mass outflow rate of ~5 M[subscript ⊙] yr[superscript −1]. Our photoionization model yields extremely small sizes (<100–500 pc) for the absorbing clouds, which we argue is typical of high column density absorbers in the circumgalactic medium (CGM). Given these small sizes and extreme kinematics, it is unclear how the clumps survive in the CGM without being destroyed by hydrodynamic instabilities. The small cloud sizes imply that even state-of-the-art cosmological simulations require more than a 1000-fold improvement in mass resolution to resolve the hydrodynamics relevant for cool gas in the CGM. 2015-09-01T16:01:07Z 2015-09-01T16:01:07Z 2014-11 2014-06 Article http://purl.org/eprint/type/JournalArticle 0035-8711 1365-2966 http://hdl.handle.net/1721.1/98292 Crighton, N. H. M., J. F. Hennawi, R. A. Simcoe, K. L. Cooksey, M. T. Murphy, M. Fumagalli, J. X. Prochaska, and T. Shanks. “Metal-Enriched, Subkiloparsec Gas Clumps in the Circumgalactic Medium of a Faint z = 2.5 Galaxy.” Monthly Notices of the Royal Astronomical Society 446, no. 1 (November 10, 2014): 18–37. https://orcid.org/0000-0003-3769-9559 en_US http://dx.doi.org/10.1093/mnras/stu2088 Monthly Notices of the Royal Astronomical Society Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Oxford University Press arXiv |
| spellingShingle | Crighton, Neil H. M. Hennawi, Joseph F. Simcoe, Robert A. Cooksey, Kathy L. Murphy, Michael T. Fumagalli, Michele Prochaska, J. Xavier Shanks, Tom Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title | Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title_full | Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title_fullStr | Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title_full_unstemmed | Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title_short | Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy |
| title_sort | metal enriched subkiloparsec gas clumps in the circumgalactic medium of a faint z 2 5 galaxy |
| url | http://hdl.handle.net/1721.1/98292 https://orcid.org/0000-0003-3769-9559 |
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