| タイトル | Spitzer 24micron Observations of Optical/Near-IR Selected Extremely Red Galaxies: Evidence for Assembly of Massive Galaxies at z approximately 1 - 2? |
| 著者（英） | G., Wilson; Fan, F.; Fadda, D.; Storrie-Lombardi, L. J.; Thompson, D. J.; Chapman, S.; Armus, L.; Soifer, B. T.; Squires, G. K.; Teplitz, H. I.; Marleau, F. R.; Appleton, P. N.; Shupe, D. L; Im, M.; Helou, G.; Surace, J.; Frayer, D. T.; Heinrichsen, I.; Lacy, M.; Choi, Philip I.; Yan, Lin |
| 著者所属（英） | Jet Propulsion Lab., California Inst. of Tech. |
| 発行日 | 2004-09-27 |
| 言語 | eng |
| 内容記述 | We carried out the direct measurement of the fraction of dusty sources in a sample of extremely red galaxies with (R-K(sub s)) greater than or equal to 5.3 mag and K(sub s) less than 20.2 mag, using from the Spitzer Space Telescope. Combining deep 24 micrometers, K(sub s)- and R-band data over an area of approximately 64 sq.arcmin in the ELAIS N1 field of the Spitzer First Look Survey (FLS), we find that 50 +/- 60% of our ERO sample have measurable 24 micrometer flux above the 3(sigma) flux limit of 40 microns Jy. This flux limit corresponds to a SFR of 12 solar mass/yr at z approximately 1, much mo previous long wavelength measurement. The 24fJ,m-detected EROs have 24-to2.2 and 24-to-0.7micrometr flux ratios consistent with infrared luminous, dusty sources at z approx. 1, and an order of magnitude too red to be explained by an infrared quiescent spiral or a pure old stellar population at any redshift. Some of these 24 micrometer-detected EROs could be AGN, however, the fraction among the whole ERO sample is probably small, 10-20%, as suggested by deep X-ray observations as well as optical spectroscopy. Keck optical spectroscopy of a sample of similarly selected EROs in the FLS field suggests that most of the EROs in ELAIS Nl are probably at z approx. 1. |
| NASA分類 | Astronomy |
| 権利 | Copyright |
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