Galaxy inclination and the IRX-beta relation: Effects on UV star-formation rate measurements at intermediate to high redshifts
| Autor: | Alexander de la Vega, Susan A. Kassin, Camilla Pacifici, Karl D. Gordon, Brett Salmon, Raymond C. Simons, S. M. Faber, Weichen Wang, Zhu Chen, Dritan Kodra, Gregory F. Snyder, Henry C. Ferguson, Pablo G. Pérez-González, Guillermo Barro |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Extinction 010308 nuclear & particles physics Star formation FOS: Physical sciences Astronomy and Astrophysics Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Astrophysics - Astrophysics of Galaxies Galaxy Redshift Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics |
| DOI: | 10.48550/arxiv.1811.03671 |
| Popis: | At intermediate and high redshifts, measurements of galaxy star-formation rates are usually based on rest-frame ultraviolet (UV) data. A correction for dust attenuation, A_UV, is needed for these measurements. This correction is typically inferred from UV spectral slopes (beta) using an equation known as "Meurer's Relation." In this paper, we study this relation at a redshift of 1.5 using images and photometric measurements in the rest-frame UV (HST) through mid-infrared (Spitzer). It is shown that massive star-forming galaxies (above 10^10 Msun) have dust corrections that are dependent on their inclination to the line-of-sight. Edge-on galaxies have higher A_UV and infrared excess (IRX=L(IR)/L(UV)) than face-on galaxies at a given beta. Interestingly, dust corrections for low-mass star-forming galaxies do not depend on inclination. This is likely because more massive galaxies have more disk-like shapes/kinematics, while low-mass galaxies are more prolate and have more disturbed kinematics. To account for an inclination-dependent dust correction, a modified Meurer's Relation is derived: A_UV=4.43+1.99 beta - 1.73 (b/a-0.67), where b/a is the galaxy axis ratio. This inclination-dependence of A_UV can be explained by a two-component model of the dust distribution inside galaxies. In such a model, the dust attenuation of edge-on galaxies has a higher contribution from a "mixture" component (dust uniformly mixed with stars in the diffuse interstellar medium), and a lower contribution from a "birth cloud" component (near-spherical dust shells surrounding young stars in H II regions) than that of face-on galaxies. The difference is caused by the larger path-lengths through disks at higher inclinations. Comment: 25 pages, 14 figures. Accepted to ApJ. Figure 4 is the key plot |
| Databáze: | OpenAIRE |
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