ﻻ يوجد ملخص باللغة العربية
As a step toward a comprehensive overview of the infrared diagnostics of the central engines and host galaxies of quasars at low redshift, we present Spitzer Space Telescope spectroscopic (5-40 {mu}m) and photometric (24, 70 and 160 {mu}m) measurements of all Palomar-Green (PG) quasars at z < 0.5 and 2MASS quasars at z < 0.3. We supplement these data with Herschel measurements at 160 {mu}m. The sample is composed of 87 optically selected PG quasars and 52 near-IR selected 2MASS quasars. Here we present the data, measure the prominent spectral features, and separate emission due to star formation from that emitted by the dusty circumnuclear torus. We find that the mid-IR (5-30 {mu}m) spectral shape for the torus is largely independent of quasar IR luminosity with scatter in the SED shape of ~ 0.2 dex. Except for the silicate features, no large difference is observed between PG (unobscured - silicate emission) and 2MASS (obscured - silicate absorption) quasars. Only mild silicate features are observed in both cases. When in emission, the peak wavelength of the silicate feature tends to be longer than 9.7 {mu}m, possibly indicating effects on grain properties near the AGN. The IR color is shown to correlate with the equivalent width of the aromatic features, indicating that the slope of the quasar mid- to far-IR SED is to first order driven by the fraction of radiation from star formation in the IR bands.
We present 2MASS $JHK_{rm s}$ photometry for 913 star clusters and candidates in the field of M31, which are selected from the latest Revised Bologna Catalog of M31 globular clusters (GCs) and candidates. The photometric measurements in this paper su
A spectral principal component analysis (SPCA) of a sample of 87 PG QSOs at $z < 0.5$ is presented for their mid-infrared spectra from Spitzer Space Telescope. We have derived the first five eigenspectra, which account for 85.2% of the mid-infrared s
Spitzer Infrared Spectrograph (IRS) observations of 3C radio galaxies and quasars shed new light on the nature of the central engines of AGN. Emission from silicate dust obscuring the central engine can be used to estimate the bolometric luminosity o
We present deep near-infrared photometry and spectroscopy of the globular cluster 2MASS-GC03 projected in the Galactic disk using MMIRS on the Clay telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea survey (VVV) data. Most pro
We present Herschel far-infrared (FIR) observations of two sub-mm bright quasars at high redshift: SDSS J1148+5251 (z=6.42) and BR 1202-0725 (z=4.69) obtained with the PACS instrument. Both objects are detected in the PACS photometric bands. The Hers