The disappearance of Lyman alpha blobs: a GALEX search at z=0.8
| Autor: | Keel, William C., III., Raymond E. White, Chapman, Scott, Windhorst, Rogier A. |
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| Rok vydání: | 2009 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/0004-6256/138/3/986 |
| Popis: | Lyman alpha blobs - luminous, spatially extended emission-line nebulae, often lacking bright continuum counterparts - are common in dense environments at high redshift. Until recently, atmospheric absorption and filter technology have limited our knowledge of any similar objects at z<2. We use GALEX slitless spectroscopy to search for similar objects in the rich environments of two known cluster and supercluster fields at z=0.8, where the instrumental sensitivity peaks. The regions around Cl 1054-0321 and Cl 0023+0423 were each observed in slitless-spectrum mode for 10-19 ksec, with accompanying direct images of 3-6 ksec to assist in recognizing continuum sources. Using several detection techniques, we find no resolved Lyman alpha emitters to a flux limit of(1.5-9) x 10^{-15} erg/ cm^2 s, on size scales of 5-30 arcseconds. This corresponds to line luminosities of (0.5-3) x 10^43 erg/s for linear scales 35-200 kpc. Comparison with both blind and targeted surveys at higher redshifts indicates that the population must have evolved in comoving density at least as strongly as (1+z)^3. These results suggest that the population of Lyman alpha blobs is specific to the the high-redshift Universe. Comment: Astronomical Journal, in press |
| Databáze: | arXiv |
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