714 research outputs found
An IRAS High Resolution Image Restoration (HIRES) Atlas of All Interacting Galaxies in the IRAS Revised Bright Galaxy Sample
We present high-resolution (30"-1') 12, 25, 60, and 100 micron images of 106
interacting galaxy systems contained in the IRAS Revised Bright Galaxy Sample
(RBGS, Sanders et al. 2003), a complete sample of all galaxies having a 60
micron flux density greater than 5.24 Jy. These systems were selected to have
at least two distinguishable galaxies separated by less than three average
galactic diameters, and thus we have excluded very widely separated systems and
very advanced mergers. The new complete survey has the same properties as the
prototype survey of Surace et al. 1993. We find no increased tendency for
infrared-bright galaxies to be associated with other infrared bright galaxies
among the widely separated pairs studied here. We find small enhancements in
far-infrared activity in multiple galaxy systems relative to RBGS
non-interacting galaxies with the same blue luminosity distribution. We also
find no differences in infrared activity (as measured by infrared color and
luminosity) between late and early-type spiral galaxies.Comment: 49 pages, 13 figures. To appear in the Astronomical Journal. Figures
have been degraded due to space considerations. A PDF version with higher
quality figures is available at
http://humu.ipac.caltech.edu/~jason/pubs/surace_hires.pd
High Spatial Resolution Near-Ir Tip/Tilt Imaging Of "Warm" Ultraluminous Infrared Galaxies
We present results from high spatial resolution (FWHM â 0.3â0.5 âł) near-IR (1.6 and 2.1ÎŒm) imaging of a complete sample of ultraluminous infrared galaxies (ULIGs) chosen to have âwarmâ mid-IR colors (f_(25)/f_(60) > 0.2) characteristic of AGN. In conjunction with our WFPC2 imaging program (Surace et al. 1998), we have found that nearly all of these systems are advanced mergers with complex nuclear morphologies. The extended underlying galaxies are detected in each system at H and KâČ, and are found to have luminosities of a few L*, similar to quasars (McLeod & Rieke 1994). Many of the circumnuclear star-forming knots seen at optical wavelengths have been detected. Based on model SEDs, their bolometric luminosities appear similar to those of the extended nuclear starbursts seen in other, less-luminous interacting systems (i.e. NGC 4038/9). Each ULIG is increasingly dominated at long wavelengths by a compact source which we identify as a putative active nucleus. The optical/near-IR colors of these putative nuclei are more extreme than the most infrared-active starburst galaxies, yet are identical to âfar-IR loudâ quasars which are in turn similar to optical quasars with significant hot (800 K) dust emission. Half of the ULIGs have dereddened nuclear near-IR luminosities comparable to those of QSOs, while the others resemble Seyferts; this may be an effect of patchy extinction and scattering. Similarities between the putative ULIG nuclei and QSO nuclei, the underlying host galaxies, and the apparent young age of the ULIGs (as evidenced by their compact star-forming knots) support the evolution of âwarmâ ULIGs into optical QSOs
The IRAS Revised Bright Galaxy Sample (RBGS)
IRAS flux densities, redshifts, and infrared luminosities are reported for
all sources identified in the IRAS Revised Bright Galaxy Sample (RBGS), a
complete flux-limited survey of all extragalactic objects with total 60 micron
flux density greater than 5.24 Jy, covering the entire sky surveyed by IRAS at
Galactic latitude |b| > 5 degrees. The RBGS includes 629 objects, with a median
(mean) sample redshift of 0.0082 (0.0126) and a maximum redshift of 0.0876. The
RBGS supersedes the previous two-part IRAS Bright Galaxy Samples, which were
compiled before the final ("Pass 3") calibration of the IRAS Level 1 Archive in
May 1990. The RBGS also makes use of more accurate and consistent automated
methods to measure the flux of objects with extended emission. Basic properties
of the RBGS sources are summarized, including estimated total infrared
luminosities, as well as updates to cross-identifications with sources from
optical galaxy catalogs established using the NASA/IPAC Extragalactic Database
(NED). In addition, an atlas of images from the Digitized Sky Survey with
overlays of the IRAS position uncertainty ellipse and annotated scale bars is
provided for ease in visualizing the optical morphology in context with the
angular and metric size of each object. The revised bolometric infrared
luminosity function, phi(L_ir), for infrared bright galaxies in the local
Universe remains best fit by a double power law, phi(L_ir) ~ L_ir^alpha, with
alpha = -0.6 (+/- 0.1), and alpha = -2.2 (+/- 0.1) below and above the
"characteristic" infrared luminosity L_ir ~ 10^{10.5} L_solar, respectively.
(Abridged)Comment: Accepted for publication in the Astronomical Journal. Contains 50
pages, 7 tables, 16 figures. Due to astro-ph space limits, only 1 of 26 pages
of Figure 1, and 1 of 11 pages of Table 7, are included; full resolution
Postscript files are available at
http://nedwww.ipac.caltech.edu/level5/March03/IRAS_RBGS/Figures/ .
Replacement: Corrected insertion of Fig. 15 (MethodCodes.ps) in LaTe
High Resolution Optical/Near-Infrared Imaging of Cool Ultraluminous Infrared Galaxies
We present high spatial resolution (FWHM 0.3-0.8") BIHK'-band imaging of a sample of ultraluminous infrared galaxies with "cool" mid-infrared colors (f25/f60 < 0.2) which select against AGN-like systems and which form a complementary sample to the "warm" ULIGs of Surace et al. (1998). We find that all of the cool ULIGs are either advanced mergers or are pre-mergers with evidence for still-separate nuclei with separations greater than 600 pc. Extended tidal features such as tails and loops as well as clustered star formation are observed in most systems. This extended tidal structure suggests a common progenitor geometry for most of the ULIGs: a plunging disk collision where the disks are highly inclined with respect to each other. The underlying host galaxies have H-band luminosities of 1-2.5 L*, very similar to that found in the "warm" ULIGs. The nuclear regions of these galaxies have morphologies and colors characteristic of a recent burst of star formation mixed with hot dust and mildly extinguished by A_v=2-5 magnitudes; only in o ne case (IRAS 22491-1808) is there evidence for a compact emission region with colors similar to an extinguished QSO. Most of the observed star-forming knots appear to have very young (10 Myr) ages based on their optical/near-infrared colors. These star-forming knots are insufficiently luminous to typically provide more than 10% of the high bolometric luminosity of the systems
Optical/Near-Infrared Imaging of Infrared-Excess Palomar-Green QSOs
Ground-based high spatial-resolution (FWHM < 0.3-0.8") optical and
near-infrared imaging (0.4-2.2um) is presented for a complete sample of
optically selected Palomar-Green QSOs with far-infrared excesses at least as
great as those of "warm" AGN-like ultraluminous infrared galaxies
(L_ir/L_big-blue-bump > 0.46). In all cases, the host galaxies of the QSOs were
detected and most have discernable two-dimensional structure. The QSO host
galaxies and the QSO nuclei are similar in magnitude at H-band. H-band
luminosities of the hosts range from 0.5-7.5 L* with a mean of 2.3 L*, and are
consistent with those found in ULIGs. Both the QSO nuclei and the host galaxies
have near-infrared excesses, which may be the result of dust associated with
the nucleus and of recent dusty star formation in the host. These results
suggest that some, but not all, optically-selected QSOs may have evolved from
an infrared-active state triggered by the merger of two similarly-sized L*
galaxies, in a manner similar to that of the ultraluminous infrared galaxies.Comment: Aastex format, 38 pages, 4 tables, 10 figures. Higher quality figures
are available in JPG forma
The Infrared Array Camera Dark Field: Far-Infrared to X-ray Data
We present 20 band photometry from the far-IR to X-ray in the Spitzer Infrared Array Camera (IRAC) dark field. The bias for the near-IR camera on Spitzer is calibrated by observing a ~20' diameter "dark" field near the north ecliptic pole roughly every two-to-three weeks throughout the mission duration of Spitzer. The field is unique for its extreme depth, low background, high quality imaging, time-series information, and accompanying photometry including data taken with Akari, Palomar, MMT, KPNO, Hubble, and Chandra. This serendipitous survey contains the deepest mid-IR data taken to date. This data set is well suited for studies of intermediate-redshift galaxy clusters, high-redshift galaxies, the first generation of stars, and the lowest mass brown dwarfs, among others. This paper provides a summary of the data characteristics and catalog generation from all bands collected to date as well as a discussion of photometric redshifts and initial and expected science results and goals. To illustrate the scientific potential of this unique data set, we also present here IRAC color-color diagrams
The IRAC Dark Field; Far- Infrared to X-ray Data
We present 20 band photometry from the far-IR to X-ray in the Spitzer IRAC
dark field. The bias for the near-IR camera on Spitzer is calibrated by
observing a ~20 arcminute diameter "dark" field near the north ecliptic pole
roughly every two-to-three weeks throughout the mission duration of Spitzer.
The field is unique for its extreme depth, low background, high quality
imaging, time-series information, and accompanying photometry including data
taken with Akari, Palomar, MMT, KPNO, Hubble, and Chandra. This serendipitous
survey contains the deepest mid-IR data taken to date. This dataset is well
suited for studies of intermediate redshift galaxy clusters, high redshift
galaxies, the first generation of stars, and the lowest mass brown dwarfs,
among others. This paper provides a summary of the data characteristics and
catalog generation from all bands collected to date as well as a discussion of
photometric redshifts and initial and expected science results and goals. To
illustrate the scientific potential of this unique dataset, we also present
here IRAC color color diagrams.Comment: 12 pages, ApJS accepte
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