Prof. Dimitra Rigopoulou

Abstract:

We study 87 extremely red objects (EROs), selected both to have color redder than R - [3.6] = 4.0 and to have confirmed spectroscopic redshifts. Together, these two constraints result in this sample populating a fairly narrow redshift range at 0.76 < z < 1.42. The key new ingredient included here is deep Spitzer Space Telescope Infrared Array Camera (IRAC) data. Based on [3.6] - [8.0] color, we demonstrate that it is possible to classify EROs as early-type galaxies, dusty starburst galaxies, or active galactic nuclei (AGNs; power-law types). We present ultraviolet-to-mid-infrared spectral energy distributions (SEDs) and Advanced Camera for Surveys (ACS) images, both of which support our simple IRAC color classification. © 2007. The American Astronomical Society. All rights reserved.

Abstract:

We report the detection of rest-frame 6.2 and 7.7 μm emission features arising from polycyclic aromatic hydrocarbons (PAHs) in the Spitzer IRS spectrum of an infrared-luminous Lyman break galaxy at z = 3.01. This is currently the highest redshift galaxy where these PAH emission features have been detected. The total IR luminosity inferred from the MIPS 24 μm and radio flux density is 2 × 10¹³ L⊙, which qualifies this object as a so-called hyperluminous infrared galaxy (HyLIRG). However, unlike local HyLIRGs, which are generally associated with QSO/AGNs and have weak or absent PAH emission features, this HyLIRG has very strong 6.2 and 7.7 μm PAH emission. We argue that intense star formation dominates the IR emission of this source, although we cannot rule out the presence of a deeply obscured AGN. This LBG appears to be a distorted system in the HST ACS F606W and F814W images, possibly indicating that a significant merger or interaction is driving the large IR luminosity. © 2007. The American Astronomical Society. All rights reserved.

Abstract:

In this the first of a series of Letters, we present a panchromatic data set in the Extended Groth Strip region of the sky. Our survey, the All-Wavelength Extended Groth Strip International Survey (AEGIS), aims to study the physical properties and evolutionary processes of galaxies at z ∼ 1. It includes the following deep, wide-field imaging data sets: Chandra/ACIS X-ray, GALEX ultraviolet, CFHT/MegaCam Legacy Survey optical, CFHT/CFH12K optical, Hubble Space Telescope/ACS optical and NICMOS near-infrared, Palomar/WIRC near-infrared, Spitzer/IRAC mid-infrared, Spitzer/MIPS far-infrared, and VLA radio continuum. In addition, this region of the sky has been targeted for extensive spectroscopy using the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10 m telescope. Our survey is compared to other large multiwavelength surveys in terms of depth and sky coverage. © 2007. The American Astronomical Sociey, All rights reserved.