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EXTENDED Lyα EMISSION FROM INTERACTING GALAXIES AT HIGH REDSHIFTS
- Source :
- The Astrophysical Journal. 773:151
- Publication Year :
- 2013
- Publisher :
- American Astronomical Society, 2013.
-
Abstract
- Recent observations have discovered a population of extended Lya sources, dubbed Lyman-alpha blobs (LABs), at high redshift z ~ 3 - 6.6. These LABs typically have a luminosity of L ~ 10^42-10^44 erg/s, and a size of tens of kiloparsecs, with some giant ones reaching up to D ~ 100 kpc. However, the origin of these LABs is not well understood. In this paper, we investigate a merger model for the formation of LABs by studying Lya emission from interacting galaxies at high redshifts by means of a combination of hydrodynamics simulations with three dimensional radiative transfer calculations. Our galaxy simulations focus on a set of binary major mergers of galaxies with a mass range of 3-7 *10^12 Msun in the redshift range of z ~ 3 -7, and we use the newly improved ART^2 code to perform the radiative transfer calculations which couple multi-wavelength continuum, ionization of hydrogen, and Lya line emission. We find that intense star formation and enhanced cooling induced by gravitational interaction produce strong Lya emission from these merging galaxies. The Lya emission appears to be extended due to the extended distribution of sources and gas. During the close encounter of galaxy progenitors when the star formation rate peaks at ~ 10^3 Msun/yr, our model produces Lya blobs with luminosity of L ~ 10^42-10^44 erg/s, and size of D ~ 10-20 kpc at z>6 and D ~ 20-50 kpc at z ~ 3, in broad agreement with observations in the same redshift range. Our results suggest that merging galaxies may produce some typical LABs as observed, but the giant ones may be produced by mergers more massive than those in our model, or a combination of mergers and cold accretion from filaments on a large scale.
- Subjects :
- Physics
education.field_of_study
010308 nuclear & particles physics
Star formation
Astrophysics::High Energy Astrophysical Phenomena
Population
Astronomy and Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Close encounter
Astrophysics
Galaxy merger
01 natural sciences
Redshift
Galaxy
Space and Planetary Science
Ionization
0103 physical sciences
Radiative transfer
education
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Subjects
Details
- ISSN :
- 15384357 and 0004637X
- Volume :
- 773
- Database :
- OpenAIRE
- Journal :
- The Astrophysical Journal
- Accession number :
- edsair.doi...........e8844776dab0f7d4d58ddb3c8463e5e6