ﻻ يوجد ملخص باللغة العربية
I discuss constraints on star formation and AGN in massive, red galaxies at z~1-3 using Spitzer observations at 3-24 micron. In particular I focus on a sample of distant red galaxies (DRGs) with J - K > 2.3 in the southern Great Observatories Origins Deep Survey (GOODS-S) field. The DRGs have typical stellar masses >10^11 solar masses. Interestingly, the majority (>50%) of these objects have 24 micron flux densities >50 micro-Jy. At these redshifts massive galaxies undergo intense (and possibly frequent) IR-active phases, which is in constrast to lower-redshift massive galaxies. If the 24 micron emission in these z~1-3 galaxies is attributed to star formation, then it implies star formation rates (SFRs) in excess of ~100 solar masses per year. These galaxies have specific SFRs equal to or exceeding the global average value at that epoch. Thus, this is an active period in their assembly. Based on their X-ray luminosities and near-IR colors, as many as 25% of the massive galaxies at z>1.5 host AGN, suggesting that the growth of supermassive black holes coincides with massive-galaxy assembly.
We investigate the properties of massive galaxies at z=1-3.5 using HST observations, ground-based near-IR imaging, and Spitzer Space Telescope observations at 3-24 micron. We identify 153 distant red galaxies (DRGs) with J-K > 2.3 mag (Vega) in the s
My colleagues and I identified distant red galaxies (DRGs) with J-K>2.3 mag in the GOODS-S field. These galaxies reside at z~1-3.5, (<z>=2.2) and based on their ACS (0.4-1 micron), ISAAC (1-2.2 micron), and IRAC (3-8 micron) photometry, they typicall
We present the results of a comprehensive Spitzer survey of 70 radio galaxies across 1<z<5.2. Using IRAC, IRS and MIPS imaging we determine the rest-frame AGN contribution to the stellar emission peak at 1.6um. The stellar luminosities are found to b
We present mid-infrared spectra and photometry of thirteen redshift 0.4<z<1 dust-reddened quasars obtained with Spitzer IRS and MIPS. We compare properties derived from their infrared spectral energy distributions (intrinsic AGN luminosity and far-in
Herschel has opened new windows into studying the evolution of rapidly star-forming galaxies out to high redshifts. Todays massive starbursts are characterized by star formation rates (SFRs) of 100+ Mo/yr and display a chaotic morphology and nucleate