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The Mid-Infrared Narrow Line Baldwin Effect Revealed by Spitzer
M. Keremedjiev, L. Hao, V. Charmandaris
We present our discovery of a narrow-line Baldwin effect, an anti-correlation between the equivalent width (EW) of a line and the flux of the associated continuum, in 5-20m mid-…
Elemental Abundances of Blue Compact Dwarfs from mid-IR Spectroscopy with Spitzer
Yanling Wu, J. Bernard-Salas, V. Charmandaris +4
We present a study of elemental abundances in a sample of thirteen Blue Compact Dwarf (BCD) galaxies, using the 10--37m high resolution spectra obtained with Spitzer/IRS.…
Spitzer Spectra of a 10 mJy Galaxy Sample and the Star Formation Rate in the Local Universe
J. R. Houck, D. W. Weedman, E. Le Floc'h +1
A complete flux-limited sample of 50 galaxies is presented having f_ν(24um) > 10mJy, chosen from a survey with the Multiband Imaging Photometer on Spitzer (MIPS) of 8.2 deg^{2} wit…
Spitzer Observations of Powerful Radio Sources
Kieran Cleary, Charles R. Lawrence, Jason A. Marshall +2
We have measured the mid-infrared radiation from an orientation-unbiased sample of powerful 3C RR galaxies and quasars using the IRS and MIPS instruments aboard the Spitzer Space T…
Dust in the Extremely Metal-Poor Blue Compact Dwarf Galaxy IZw18: The Spitzer Mid-Infrared View
Yanling Wu, V. Charmandaris, L. K. Hunt +5
IZw18, a blue compact dwarf (BCD) galaxy with the 2nd lowest metallicity measured in a star-forming object, has been observed with all three instruments on board the Spitzer Space…
Spitzer Observations of 3C Quasars and Radio Galaxies: Mid-Infrared Properties of Powerful Radio Sources
K. Cleary, C. R. Lawrence, J. A. Marshall +2
We have measured mid-infrared radiation from an orientation-unbiased sample of 3CRR galaxies and quasars at redshifts 0.4 < z < 1.2 with the IRS and MIPS instruments on the Spitzer…
The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
Lei Hao, D. W. Weedman, H. W. W. Spoon +4
A sample of 196 AGNs and ULIRGs observed by the Infrared Spectrograph (IRS) on Spitzer is analyzed to study the distribution of the strength of the 9.7 micron silicate feature. Ave…
Mid-IR Galaxy Classification Based on Silicate Obscuration and PAH Equivalent Width
H. W. W. Spoon, J. A. Marshall, J. R. Houck +5
We present a new diagnostic diagram for mid-infrared spectra of infrared galaxies based on the equivalent width of the 6.2 micron PAH emission feature and the strength of the 9.7 m…
Deep Mid-Infrared Silicate Absorption as a Diagnostic of Obscuring Geometry Toward Galactic Nuclei
N. A. Levenson, M. M. Sirocky, L. Hao +4
The silicate cross section peak near 10um produces emission and absorption features in the spectra of dusty galactic nuclei observed with the Spitzer Space Telescope. Especially in…
The Mid-IR Properties of Starburst Galaxies from Spitzer-IRS Spectroscopy
B. R. Brandl, J. Bernard-Salas, H. W. W. Spoon +14
We present 5-38um mid-infrared spectra at a spectral resolution of R~65-130 of a large sample of 22 starburst nuclei taken with the Infrared Spectrograph IRS on board the Spitzer S…
Spitzer IRS Spectra of Optically Faint Infrared Sources with Weak Spectral Features
D. W. Weedman, B. T. Soifer, Lei Hao +15
Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope (Spitzer) for 58 sources having f(24 micron) > 0.75…
Spatially Resolved Spitzer Spectroscopy of the Starburst Nucleus in NGC 5253
P. Beirao, B. R. Brandl, D. Devost +3
We present new Spitzer Space Telescope data on the nearby, low-metallicity starburst galaxy NGC 5253, from the Infrared Array Camera IRAC and the Infrared Spectrograph IRS. The mid…
Type II Quasars from the Sloan Digital Sky Survey: V. Imaging host galaxies with the Hubble Space Telescope
Nadia L. Zakamska, Michael A. Strauss, Julian H. Krolik +7
Type II quasars are luminous Active Galactic Nuclei whose centers are obscured by large amounts of gas and dust. In this paper we present 3-band HST images of nine type II quasars…
Hosts of Type II Quasars: an HST Study
Nadia L. Zakamska, Michael A. Strauss, Julian H. Krolik +6
Type II quasars are luminous Active Galactic Nuclei whose centers are obscured by large amounts of gas and dust. In this contribution we present 3-band HST images of nine type II q…
Silicate Emission in the Spitzer IRS spectrum of FSC 10214+4724
H. I. Teplitz, L. Armus, B. T. Soifer +12
We present the first MIR spectrum of the z=2.2856 ultraluminous, infrared galaxy FSC 10214+4724, obtained with the Infrared Spectrograph onboard the Spitzer Space Telescope. The sp…
Mid Infrared Properties of Low Metallicity Blue Compact Dwarf Galaxies From Spitzer/IRS
Yanling Wu, V. Charmandaris, Lei Hao +4
We present a {\em Spitzer}-based mid-infrared study of a large sample of Blue Compact Dwarf galaxies (BCD) using the Infrared Spectrograph (IRS), including the first mid-IR spectru…
Mid-Infrared Spectra of Classical AGN Observed with the Spitzer Space Telescope
D. W. Weedman, Lei Hao, S. J. U. Higdon +6
Full low resolution (65<R<130) and high resolution (R~600) spectra between 5 microns and 37 microns obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope are…
The UV, Optical, and IR Properties of SDSS Sources Detected by GALEX
Marcel A. Agueros, Zeljko Ivezic, Kevin R. Covey +18
We discuss the UV, optical, and IR properties of the SDSS sources detected by GALEX as part of its All-sky Imaging Survey Early Release Observations. Virtually all of the GALEX sou…
The Detection of Silicate Emission from Quasars at 10 and 18 Microns
Lei Hao, H. W. W. Spoon, G. C. Sloan +8
We report the spectroscopic detection of silicate emission at 10 and 18 microns in five PG quasars, the first detection of these two features in galaxies outside the Local Group. T…
Candidate Type II Quasars from the Sloan Digital Sky Survey: I. Selection and Optical Properties of a Sample at 0.3<Z<0.83
Nadia L. Zakamska, Michael A. Strauss, Julian H. Krolik +12
Type II quasars are the long-sought luminous analogs of type II (narrow emission line) Seyfert galaxies, suggested by unification models of active galactic nuclei (AGN) and postula…
Evolution of the Cluster Correlation Function
Neta A. Bahcall, Lei Hao, Paul Bode +1
We study the evolution of the cluster correlation function and its richness-dependence from z = 0 to z = 3 using large-scale cosmological simulations. A standard flat LCDM model wi…
Discovery of Eight New Extremely Metal--Poor Galaxies in the Sloan Digital Sky Survey
Alexei Y. Kniazev, Eva K. Grebel, Lei Hao +3
We report the discovery of eight new extremely metal-poor galaxies (XMPGs; 12+log(O/H) < 7.65) and the recovery of four previously known or suspected XMPGs (IZw18, HS0822+3542, HS0…
Double-Peaked Low-Ionization Emission Lines in Active Galactic Nuclei
Iskra V. Strateva, Michael A. Strauss, Lei Hao +1
We present a new sample of 116 double-peaked Balmer line Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey. Double-peaked emission lines are believed to origi…
The Richness-Dependent Cluster Correlation Function: Early SDSS Data
Neta A. Bahcall, Feng Dong, Lei Hao +4
The cluster correlation function and its richness dependence are determined from 1108 clusters of galaxies -- the largest sample of clusters studied so far -- found in 379 deg^2 of…