We present a homogeneous 2MASS bright galaxy catalogue at low Galactic latitudes (|b|<=10.0{deg}, called Zone of Avoidance) which is complete to a Galactic extinction-corrected magnitude of KS^o^<=11.25m. It also includes galaxies in regions of high foreground extinctions (E(B-V)>0.95mag) situated at higher latitudes. This catalogue forms the basis of studies of large-scale structures, flow fields and extinction across the ZoA and complements the ongoing 2MASS Redshift and Tully-Fisher surveys. It comprises 3763 galaxies, 70% of which have at least one radial velocity measurement in the literature. The catalogue is complete up to star density levels of logN*/deg^2^<4.5 and at least for A(K)<0.6mag and likely as high as A(K)=20mag. Thus the ZoA in terms of bright NIR galaxies covers only 2.5-4% of the whole sky. We use a diameter-dependent extinction correction to compare our sample with an unobscured, high-latitude sample. While the correction to the Ks -band magnitude is sufficient, the corrected diameters are too small by about 4" on average. The omission of applying such a diameter-dependent extinction correction may lead to a biased flow field even at intermediate extinction values as found in the 2MRS survey. A slight dependence of galaxy colour with stellar density indicates that unsubtracted foreground stars make galaxies appear bluer. Furthermore, far-infrared sources in the DIRBE/IRAS extinction maps that were not removed at low latitudes affect the foreground extinction corrections of three galaxies and may weakly affect a further estimated ~20% of our galaxies.
We present observations of ~7deg^2^ of the North American and Pelican Nebulae region at 24, 70, and 160um with the Spitzer Space Telescope Multiband I] ing Photometer for Spitzer (MIPS). We incorporate the MIPS observations with earlier Spitzer Infrared Array Camera (IRAC) observations, as well as archival near-infrared (IR) and optical data. We use the MIPS data to identify 1286 young stellar object (YSO) candidates. IRAC data alone can identify 806 more YSO candidates, for a total of 2076 YSO candidates. Prior to the Spitzer observations, there were only ~200 YSOs known in this region. Three subregions within the complex are highlighted as clusters: the Gulf of Mexico, the Pelican, and the Pelican's Hat. The Gulf of Mexico cluster is subject to the highest extinction (A_V_ at least ~30) and has the widest range of infrared colors of the three clusters, including the largest excesses and by far the most point-source detections at 70um. Just 3% of the cluster members were previously identified; we have redefined this cluster as about 10-100 times larger (in projected area) than was previously realized.
We present a 9deg^2^ map of the North American and Pelican Nebulae regions obtained in all four Infrared Array Camera (IRAC) channels with the Spitzer Space Telescope. The resulting photometry is merged with that at JHKs from Two Micron All Sky Survey and a more spatially limited BVI survey from previous ground-based work. We use a mixture of color-color diagrams to select a minimally contaminated set of more than 1600 objects that we claim are young stellar objects (YSOs) associated with the star-forming region. Because our selection technique uses infrared excess as a requirement, our sample is strongly biased against inclusion of Class III YSOs. The distribution of IRAC spectral slopes for our YSOs indicates that most of these objects are Class II, with a peak toward steeper spectral slopes but a substantial contribution from a tail of Flat spectrum and Class I type objects. By studying the small fraction of the sample that is optically visible, we infer a typical age of a few Myr for the low-mass population. The young stars are clustered, with about a third of them located in eight clusters that are located within or near the LDN 935 dark cloud. Half of the YSOs are located in regions with surface densities higher than 1000YSOs/deg^2^. The Class I objects are more clustered than the Class II stars.
The NASA/IPAC Extragalactic Database (NED) provides a comprehensive fusion
of multi-wavelength data for hundreds of millions of objects located beyond
the Milky Way galaxy. As new observations are published in NASA mission
archives, journal articles and sky survey catalogs, they are cross-identified
with prior measurements and integrated in a unified database. Numerous derived
quantities are also provided to facilitate scientific research. For more
information see http://ned.ipac.caltech.edu/
NED service to query for Objects by Reference Code:
The NASA/IPAC Extragalactic Database (NED) provides a comprehensive fusion
of multi-wavelength data for hundreds of millions of objects located beyond
the Milky Way galaxy.
This service searches NED's master list of extragalactic objects by (19 digit)
journal reference code. It returns object names, positions, and
redshifts if available. It also returns counts of bibliographic references, notes,
photometry, positions, redshifts, diameters, and positional associations.
Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media. The NRAO is funded by the National Science Foundation (NSF) under the terms of a cooperative agreement between the NSF and Associated Universities, Inc. (AUI), a science management corporation.
Hyperluminous infrared galaxies (HLIRGs) are shown to have been more abundant in early epochs. The small samples used in earlier studies are not sufficient to draw robust statistical conclusions regarding the physical properties and the power sources of these extreme infrared (IR) bright galaxies. We make use of multi-wavelength data of a large hyper luminous galaxy sample to derive the main physical properties, such as stellar mass, star formation rate (SFR), volume density, and the contribution to the cosmic stellar mass density and the cosmic SFR density. We also study the black hole (BH) growth rate and its relationship with the SFR of the host galaxy. We selected 526 HLIRGs in three deep fields (Bootes, Lockman-Hole, and ELAIS-N1) and adopted two spectral energy distribution (SED) fitting codes: CIGALE, which assumes energy balance, and CYGNUS, which is based on radiative transfer models and does not adopt an energy balance principle. We used two different active galactic nucleus (AGN) models in CIGALE and three AGN models in CYGNUS to compare results that were estimated using different SED fitting codes and a range of AGN models. The stellar mass, total IR luminosity, and AGN luminosity agree well among different models, with a typical median offset of 0.1dex. The SFR estimates show the largest dispersions (up to 0.5dex). This dispersion has an impact on the subsequent analysis, which may suggest that the previous contradictory results could partly have been due to the different choices in methods. HLIRGs are ultra-massive galaxies, with 99% of them having stellar masses larger than 10^11^M_{sun}_. Our results reveal a higher space density of ultra-massive galaxies than what was found by previous surveys or predicted via simulations. We find that HLIRGs contribute more to the cosmic SFR density as redshift increases. In terms of BH growth, the two SED fitting methods provide different results. We can see a clear trend in whereby SFR decreases as AGN luminosity increases when using CYGNUS estimates. This may possibly imply quenching by AGN in this case, whereas this trend is much weaker when using CIGALE estimates. This difference is also influenced by the dispersion between SFR estimates obtained by the two codes.
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