MIPSGAL is a278 deg2
278
deg
2
survey of the inner Galactic plane using the Multiband Infrared Photometer forSpitzeraboard theSpitzer Space Telescope. The survey field was imaged in two ...passbands, 24 and 70 μm with resolutions of 6″ and 18″, respectively. The survey was designed to provide a uniform, well-calibrated and well-characterized data set for general inquiry of the inner Galactic plane and as a longer-wavelength complement to the shorter-wavelengthSpitzersurvey of the Galactic plane: Galactic Plane Infrared Mapping Survey Extraordinaire. The primary science drivers of the current survey are to identify all high-mass (
M > 5 M
⊙
M
>
5
M
⊙
) protostars in the inner Galactic disk and to probe the distribution, energetics, and properties of interstellar dust in the Galactic disk. The observations were planned to minimize data artifacts due to image latents at 24 μm and to provide full coverage at 70 μm. Observations at ecliptic latitudes within 15° of the ecliptic plane were taken at multiple epochs to help reject asteroids. The data for the survey were collected in three epochs, 2005 September–October, 2006 April, and 2006 October with all of the data available to the public. The estimated point-source sensitivities of the survey are 2 and 75 mJy (3 σ) at 24 and 70 μm, respectively. Additional data processing was needed to mitigate image artifacts due to bright sources at 24 μm and detector responsivity variations at 70 μm due to the large dynamic range of the Galactic plane. Enhanced data products including artifact-mitigated mosaics and point-source catalogs are being produced with the 24 μm mosaics already publicly available from the NASA/IPAC Infrared Science Archive. Some preliminary results using the enhanced data products are described.
We report the first direct detection with Spitzer of galaxy filaments. Using Spitzer and ancillary optical data, we have discovered two filamentary structures in the outskirts of the cluster Abell ...1763. Both filaments point toward Abell 1770, which lies at the same redshift as Abell 1763 (z = 0.23), at a projected distance of similar to 13 Mpc. The X-ray cluster emission is elongated along the same direction. Most of the far-infrared emission is powered by star formation. According to the optical spectra, only one of the cluster members is classified as an active galactic nucleus. Star formation is clearly enhanced in galaxies along the filaments: the fraction of starburst galaxies in the filaments is more than twice than that in other cluster regions. We speculate that these filaments are feeding the cluster Abell 1763 by the infall of galaxies and galaxy groups. Evidence for one of these groups is provided by the analysis of galaxy kinematics in the central cluster region.
Point‐Source Extraction with MOPEX Makovoz, David; Marleau, Francine R.
Publications of the Astronomical Society of the Pacific,
10/2005, Letnik:
117, Številka:
836
Journal Article
Recenzirano
Odprti dostop
MOPEX (Mosaicking and Point‐source Extraction) is a package developed at theSpitzerScience Center for astronomical image processing. We report on the point‐source extraction capabilities of MOPEX. ...Point‐source extraction is implemented as a two‐step process: point‐source detection and profile fitting. Nonlinear matched filtering of input images can be performed optionally to increase the signal‐to‐noise ratio and improve detection of faint point sources. Point response function (PRF) fitting of point sources produces the final point‐source list, which includes the fluxes and improved positions of the point sources, along with other parameters characterizing the fit. Passive and active deblending allows for successful fitting of confused point sources. Aperture photometry can also be computed for every extracted point source for an unlimited number of aperture sizes. The PRF is estimated directly from the input images. The implementation of efficient methods of background and noise estimation and a modified simplex algorithm contribute to the computational efficiency of MOPEX. The package is implemented as a loosely connected set of Perl scripts, each script running a number of modules written in C/C++. Input parameter setting is done through name lists, ASCII configuration files. We present applications of point‐source extraction to the mosaic images taken at 24 and 70 μm with the Multiband Imaging Photometer (MIPS) as part of theSpitzerextragalactic First Look Survey, and to a Digital Sky Survey image. Completeness and reliability of point‐source extraction is computed using simulated data.
New images of M31 at 24, 70, and 160 km taken with the Multiband Imaging Photometer for Spitzer (MIPS) reveal the morphology of the dust in this galaxy. This morphology is well represented by a ...composite of two logarithmic spiral arms and a circular ring (radius 610 kpc) of star formation offset from the nucleus. The two spiral arms appear to start at the ends of a bar in the nuclear region and extend beyond the star-forming ring. As has been found in previous work, the spiral arms are not continuous, but composed of spiral segments. The star-forming ring is very circular except for a region near M32 where it splits. The lack of well-defined spiral arms and the prominence of the nearly circular ring suggest that M31 has been distorted by interactions with its satellite galaxies. Using new dynamical simulations of M31 interacting with M32 and NGC 205, we find that, qualitatively, such interactions can produce an offset, split ring like that seen in the MIPS images.
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