ON THE DIFFUSE Lyα HALO AROUND Lyα EMITTING GALAXIES

Journal Article · Wed Jun 10 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/806/1/46· OSTI ID:22522335

Lake, Ethan; Zheng, Zheng; Sadoun, Raphael ^[1]; Cen, Renyue ^[2]; Momose, Rieko; Ouchi, Masami ^[3]

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1. Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States)
2. Princeton University Observatory, Princeton, NJ 08544 (United States)
3. Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

Lyα photons scattered by neutral hydrogen atoms in the circumgalactic media or produced in the halos of star-forming galaxies are expected to lead to extended Lyα emission around galaxies. Such low surface brightness Lyα halos (LAHs) have been detected by stacking Lyα images of high-redshift star-forming galaxies. We study the origin of LAHs by performing radiative transfer modeling of nine z = 3.1 Lyα emitters (LAEs) in a high resolution hydrodynamic cosmological galaxy formation simulation. We develop a method of computing the mean Lyα surface brightness profile of each LAE by effectively integrating over many different observing directions. Without adjusting any parameters, our model yields an average Lyα surface brightness profile in remarkable agreement with observations. We find that observed LAHs cannot be accounted for solely by photons originating from the central LAE and scattered to large radii by hydrogen atoms in the circumgalactic gas. Instead, Lyα emission from regions in the outer halo is primarily responsible for producing the extended LAHs seen in observations, which potentially includes both star-forming and cooling radiation. With the limit on the star formation contribution set by the ultraviolet halo measurement, we find that cooling radiation can play an important role in forming the extended LAHs. We discuss the implications and caveats of such a picture.

• OSTI ID: 22522335
• Journal Information: Astrophysical Journal, Vol. 806, 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
ATOMS
BRIGHTNESS
COSMOLOGY
GALACTIC EVOLUTION
GALAXIES
HYDROGEN
IMAGES
LYMAN LINES
PHOTONS
RADIANT HEAT TRANSFER
RED SHIFT
RESOLUTION
SCATTERING
STAR EVOLUTION
STARS
ULTRAVIOLET RADIATION