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The connection between galaxy environment and the luminosity function slopes of star-forming regions

Cook, David O. and Dale, Daniel A. and Lee, Janice C. and Thilker, David and Calzetti, Daniela and Kennicutt, Robert C. (2016) The connection between galaxy environment and the luminosity function slopes of star-forming regions. Monthly Notices of the Royal Astronomical Society, 462 (4). pp. 3766-3799. ISSN 0035-8711.

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We present the first study of GALEX far-ultraviolet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ∼65 000 star-forming regions (i.e. FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. A final sample of 82 galaxies with reliable luminosity functions are used to define these relationships and represent the largest sample of galaxies with the largest range of galaxy properties used to study the connection between luminosity function properties and galaxy environment. We find that α correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities (Σ_(SFR)) tend to have flatter luminosity function slopes. In addition, we find that neither stochastic sampling of the luminosity function in galaxies with low-number statistics nor the effects of blending due to distance can fully account for these trends. We hypothesize that the flatter slopes in high Σ_(SFR) galaxies is due to higher gas densities and higher star formation efficiencies which result in proportionally greater numbers of bright star-forming regions. Finally, we create a composite luminosity function composed of star-forming regions from many galaxies and find a break in the luminosity function at brighter luminosities. However, we find that this break is an artefact of varying detection limits for galaxies at different distances.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Cook, David O.0000-0002-6877-7655
Dale, Daniel A.0000-0002-5782-9093
Lee, Janice C.0000-0002-2278-9407
Thilker, David0000-0002-8528-7340
Calzetti, Daniela0000-0002-5189-8004
Kennicutt, Robert C.0000-0001-5448-1821
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 July 12. Received 2016 July 2. In original form 2016 March 10. First published online August 12, 2016. We acknowledge the helpful comments provided by the referee. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by National Aeronautics and Space Administration (NASA) through contract 1336000 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. This research has made use of the NASA/IPAC Extragalactic Database, which is operated by JPL/Caltech, under contract with NASA. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:galaxies: dwarf – galaxies: irregular – Local Group – galaxies: spiral – galaxies: star clusters: general – galaxies: star formation
Issue or Number:4
Record Number:CaltechAUTHORS:20161114-131924115
Persistent URL:
Official Citation:David O. Cook, Daniel A. Dale, Janice C. Lee, David Thilker, Daniela Calzetti, and Robert C. Kennicutt The connection between galaxy environment and the luminosity function slopes of star-forming regions MNRAS (November 11, 2016) Vol. 462 3766-3799 doi:10.1093/mnras/stw1694 first published online August 12, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71998
Deposited By: Tony Diaz
Deposited On:15 Nov 2016 23:24
Last Modified:09 Mar 2020 13:19

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