Constraining the Lyα escape fraction with far-infrared observations of Lyα emitters

Journal Article · Tue May 20 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/787/1/9· OSTI ID:22356887

Wardlow, Julie L.; Calanog, J.; Cooray, A. ^[1]; Malhotra, S.; Zheng, Z.; Rhoads, J. ^[2]; Finkelstein, S. ^[3]; Bock, J.; Bridge, C. ^[4]; Ciardullo, R.; Gronwall, C. ^[5]; Conley, A. ^[6]; Farrah, D. ^[7]; Gawiser, E. ^[8]; Heinis, S. ^[9]; Ibar, E. ^[10]; Ivison, R. J. ^[11]; Marsden, G. ^[12]; Oliver, S. J. ^[13]; others, and

---

1. Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
2. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
3. The University of Texas at Austin, Austin, TX 78712 (United States)
4. California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
5. Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
6. Center for Astrophysics and Space Astronomy 389-UCB, University of Colorado, Boulder, CO 80309 (United States)
7. Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)
8. Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)
9. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
10. UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
11. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
12. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)
13. Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)

We study the far-infrared properties of 498 Lyα emitters (LAEs) at z = 2.8, 3.1, and 4.5 in the Extended Chandra Deep Field-South, using 250, 350, and 500 μm data from the Herschel Multi-tiered Extragalactic Survey and 870 μm data from the LABOCA ECDFS Submillimeter Survey. None of the 126, 280, or 92 LAEs at z = 2.8, 3.1, and 4.5, respectively, are individually detected in the far-infrared data. We use stacking to probe the average emission to deeper flux limits, reaching 1σ depths of ∼0.1 to 0.4 mJy. The LAEs are also undetected at ≥3σ in the stacks, although a 2.5σ signal is observed at 870 μm for the z = 2.8 sources. We consider a wide range of far-infrared spectral energy distributions (SEDs), including an M82 and an Sd galaxy template, to determine upper limits on the far-infrared luminosities and far-infrared-derived star formation rates of the LAEs. These star formation rates are then combined with those inferred from the Lyα and UV emission to determine lower limits on the LAEs' Lyα escape fraction (f {sub esc}(Lyα)). For the Sd SED template, the inferred LAEs f {sub esc}(Lyα) are ≳ 30% (1σ) at z = 2.8, 3.1, and 4.5, which are all significantly higher than the global f {sub esc}(Lyα) at these redshifts. Thus, if the LAEs f {sub esc}(Lyα) follows the global evolution, then they have warmer far-infrared SEDs than the Sd galaxy template. The average and M82 SEDs produce lower limits on the LAE f {sub esc}(Lyα) of ∼10%-20% (1σ), all of which are slightly higher than the global evolution of f {sub esc}(Lyα), but consistent with it at the 2σ-3σ level.

• OSTI ID: 22356887
• Journal Information: Astrophysical Journal, Vol. 787, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
EMISSION
ENERGY SPECTRA
EVOLUTION
FAR INFRARED RADIATION
GALAXIES
LUMINOSITY
LYMAN LINES
RED SHIFT
STACKS
STARS