10 research outputs found
No Evidence for Evolution in the Far-Infrared-Radio Correlation out to z ~ 2 in the eCDFS
We investigate the 70 um Far-Infrared Radio Correlation (FRC) of star-forming
galaxies in the Extended Chandra Deep Field South (ECDFS) out to z > 2. We use
70 um data from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL),
which comprises the most sensitive (~0.8 mJy rms) and extensive far-infrared
deep field observations using MIPS on the Spitzer Space Telescope, and 1.4 GHz
radio data (~8 uJy/beam rms) from the VLA. In order to quantify the evolution
of the FRC we use both survival analysis and stacking techniques which we find
give similar results. We also calculate the FRC using total infrared luminosity
and rest-frame radio luminosity, qTIR, and find that qTIR is constant (within
0.22) over the redshift range 0 - 2. We see no evidence for evolution in the
FRC at 70 um which is surprising given the many factors that are expected to
change this ratio at high redshifts.Comment: 18 pages, 13 figures. Accepted for publication in Ap
Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. II. 70 micron Imaging
The absolute calibration and characterization of the Multiband Imaging
Photometer for Spitzer (MIPS) 70 micron coarse- and fine-scale imaging modes
are presented based on over 2.5 years of observations. Accurate photometry
(especially for faint sources) requires two simple processing steps beyond the
standard data reduction to remove long-term detector transients. Point spread
function (PSF) fitting photometry is found to give more accurate flux densities
than aperture photometry. Based on the PSF fitting photometry, the calibration
factor shows no strong trend with flux density, background, spectral type,
exposure time, or time since anneals. The coarse-scale calibration sample
includes observations of stars with flux densities from 22 mJy to 17 Jy, on
backgrounds from 4 to 26 MJy sr^-1, and with spectral types from B to M. The
coarse-scale calibration is 702 +/- 35 MJy sr^-1 MIPS70^-1 (5% uncertainty) and
is based on measurements of 66 stars. The instrumental units of the MIPS 70
micron coarse- and fine-scale imaging modes are called MIPS70 and MIPS70F,
respectively. The photometric repeatability is calculated to be 4.5% from two
stars measured during every MIPS campaign and includes variations on all time
scales probed. The preliminary fine-scale calibration factor is 2894 +/- 294
MJy sr^-1 MIPS70F^-1 (10% uncertainty) based on 10 stars. The uncertainty in
the coarse- and fine-scale calibration factors are dominated by the 4.5%
photometric repeatability and the small sample size, respectively. The 5-sigma,
500 s sensitivity of the coarse-scale observations is 6-8 mJy. This work shows
that the MIPS 70 micron array produces accurate, well calibrated photometry and
validates the MIPS 70 micron operating strategy, especially the use of frequent
stimulator flashes to track the changing responsivities of the Ge:Ga detectors.Comment: 19 pages, PASP, in pres
First look at the Fomalhaut debris disk with the Spitzer Space Telescope
We present Spitzer Space Telescope early release observations of Fomalhaut, a nearby A-type star with dusty circumstellar debris. The disk is spatially resolved at 24, 70, and 160 � m using the Multiband Imaging Photometer for Spitzer (MIPS). While the disk orientation and outer radius are comparable to values measured in the submillimeter, the disk inner radius cannot be precisely defined: the central hole in the submillimeter ring is at least partially filled with emission from warm dust, seen inSpitzerInfrared Spectrograph (IRS) 17.5‐34 � m spectra and MIPS 24 � m images. The disk surface brightness becomes increasingly asymmetric toward shorter wavelengths, with the south-southeast ansa always brighter than the north-northwest one. This asymmetry may reflect perturbations on the disk by an unseen interior planet. Subject headingg circumstellar matter — infrared: stars — planetary systems — stars: individual (Fomalhaut