تقرير
Lyman-Alpha-Emitting Galaxies at z = 2.1 in ECDF-S: Building Blocks of Typical Present-day Galaxies?
| العنوان: | Lyman-Alpha-Emitting Galaxies at z = 2.1 in ECDF-S: Building Blocks of Typical Present-day Galaxies? |
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| المؤلفون: | Guaita, L., Gawiser, E., Padilla, N., Francke, H., Bond, N. A., Gronwall, C., Ciardullo, R., Feldmeier, J. J., Sinawa, S., Blanc, G. A., Virani, S. |
| المصدر: | Astrophys.J.714:255-269,2010 |
| سنة النشر: | 2009 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies |
| الوصف: | We discovered a sample of 250 Ly-Alpha emitting (LAE) galaxies at z=2.1 in an ultra-deep 3727 A narrow-band MUSYC image of the Extended Chandra Deep Field-South. LAEs were selected to have rest-frame equivalent widths (EW) > 20 A and emission line fluxes > 2.0 x 10^(-17)erg /cm^2/s, after carefully subtracting the continuum contributions from narrow band photometry. The median flux of our sample is 4.2 x 10^(-17)erg/cm^2/s, corresponding to a median Lya luminosity = 1.3 x 10^(42) erg/s at z=2.1. At this flux our sample is > 90% complete. Approximately 4% of the original NB-selected candidates were detected in X-rays by Chandra, and 7% were detected in the rest-frame far-UV by GALEX. At luminosity>1.3 x 10^42 erg/s, the equivalent width distribution is unbiased and is represented by an exponential with scale-length of 83+/-10 A. Above this same luminosity threshold, we find a number density of 1.5+/-0.5 x 10^-3 Mpc^-3. Neither the number density of LAEs nor the scale-length of their EW distribution show significant evolution from z=3 to z=2. We used the rest frame UV luminosity to estimate a median star formation rate of 4 M_(sun) /yr. The median rest frame UV slope, parametrized by B-R, is that typical of dust-free, 0.5-1 Gyr old or moderately dusty, 300-500 Myr old populations. Approximately 40% of the sample occupies the z~2 star-forming galaxy locus in the UVR two color diagram. Clustering analysis reveals that LAEs at z=2.1 have r_0=4.8+/-0.9 Mpc and a bias factor b=1.8+/-0.3. This implies that z=2.1 LAEs reside in dark matter halos with median masses Log(M/M_(sun))=11.5^(+0.4)_(-0.5), which are among of the lowest-mass halos yet probed at this redshift. We used the Sheth-Tormen conditional mass function to study the descendants of these LAEs and found that their typical present-day descendants are local galaxies with L* properties, like the Milky Way. Comment: 35 pages, 9 figures, ApJ, in press |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1088/0004-637X/714/1/255 |
| URL الوصول: | http://arxiv.org/abs/0910.2244 |
| رقم الأكسشن: | edsarx.0910.2244 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1088/0004-637X/714/1/255 |
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