The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out a 250, 350, and 500um survey of the Galactic plane encompassing the Vela Molecular Ridge, with the primary goal of identifying the coldest dense cores possibly associated with the earliest stages of star formation. Here, we present the results from observations of the Vela-D region, covering about 4deg^2^, in which we find 141 BLAST cores. We exploit existing data taken with the Spitzer MIPS, IRAC, and SEST-SIMBA instruments to constrain their (single-temperature) spectral energy distributions, assuming a dust emissivity index {beta}=2.0. This combination of data allows us to determine the temperature, luminosity, and mass of each BLAST core, and also enables us to separate starless from protostellar sources. We also analyze the effects that the uncertainties on the derived physical parameters of the individual sources have on the overall physical properties of starless and protostellar cores, and we find that there appear to be a smooth transition from the pre- to the protostellar phase. In particular, for protostellar cores we find a correlation between the MIPS24 flux, associated with the central protostar, and the temperature of the dust envelope. We also find that the core mass function of the Vela-D cores has a slope consistent with other similar (sub)millimeter surveys.
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently surveyed ~8.7deg^2^ centered on Great Observatories Origins Deep Survey-South at 250, 350, and 500um. In Dye et al. (2009, Cat. J/ApJ/703/285), we presented the catalog of sources detected at 5{sigma} in at least one band in this field and the probable counterparts to these sources in other wavebands. In this paper, we present the results of a redshift survey in which we succeeded in measuring redshifts for 82 of these counterparts. The spectra show that the BLAST counterparts are mostly star-forming galaxies but not extreme ones when compared to those found in the Sloan Digital Sky Survey. Roughly one quarter of the BLAST counterparts contain an active nucleus. We have also investigated the cases where there are two possible counterparts to the BLAST source, finding that in at least half of these there is evidence that the two galaxies are physically associated, either because they are interacting or because they are in the same large-scale structure. Finally, we have made the first direct measurements of the luminosity function in the three BLAST bands.
We present first results from an unbiased 50deg^2^ submillimeter Galactic survey at 250, 350, and 500um from the 2006 flight of the Balloon-borne Large Aperture Submillimeter Telescope. The map has resolution ranging from 36" to 60" in the three submillimeter bands spanning the thermal emission peak of cold starless cores. We determine the temperature, luminosity, and mass of more than 1000 compact sources in a range of evolutionary stages and an unbiased statistical characterization of the population. From comparison with C^18^O data, we find the dust opacity per gas mass, {kappa}r=0.16cm^2^/g at 250um, for cold clumps. We find that 2% of the mass of the molecular gas over this diverse region is in cores colder than 14K, and that the mass function for these cold cores is consistent with a power law with index {alpha}=-3.22+/-0.14 over the mass range 14M_{sun}_<M<80M_{sun}_.
We have carried out the first general submillimeter analysis of the field toward GRSMC 45.46+0.05, a massive star-forming region in Aquila. The deconvolved 6{deg}^2^ (3{deg}x2{deg}) maps provided by BLAST in 2005 at 250, 350, and 500um were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8GHz have also been used to characterize the Ultracompact HII regions (UCHIIRs) within the main clumps. By means of the BLAST maps, we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds.
We present a study to search for, and characterise blazar candidates among the Fermi/LAT 3FGL catalogue using machine-learning classification methods. Classifiers are based on the exploitation of statistical differences imprinted in the 3FGL Fermi/LAT catalogue, such as variability and spectral shape, between different populations of sources.
We report the identification of blazar candidates behind the Magellanic Clouds. The objects were selected from the Magellanic Quasars Survey (MQS), which targeted the entire Large Magellanic Cloud (LMC) and 70% of the Small Magellanic Cloud (SMC). Among the 758 MQS quasars and 898 of the unidentified (featureless spectra) objects, we identified a sample of 44 blazar candidates, including 27 flat-spectrum radio quasars and 17 BL Lacertae objects, respectively. All the blazar candidates from our sample were identified with respect to their radio, optical, and midinfrared properties. The newly selected blazar candidates possess the long-term, multicolor photometric data from the Optical Gravitational Lensing Experiment, multicolor midinfrared observations, and archival radio data for one frequency at least. In addition, for nine of them, the radio polarization data are available. With such data, these objects can be used to study the physics behind the blazar variability detected in the optical and midinfrared bands, as a tool to investigate magnetic field geometry of the LMC and SMC, and as an exemplary sample of point-like sources most likely detectable in the {gamma}-ray range with the newly emerging Cherenkov Telescope Array.
Supplementing existing survey data with Very Large Array (VLA) observations, we have extended {gamma}-ray counterpart identifications down to decl.=-40{deg} using our "figure-of-merit" approach. We find blazar counterparts for 70% of EGRET sources above decl.=-40{deg} away from the Galaxy. Spectroscopic confirmation is in progress, and spectra for 24 sources are presented here. We find evidence that increased exposure in the bulge region allowed EGRET to detect relatively faint blazars; a clear excess of nonblazar objects in this region, however, argues for an additional (new) source class.
The observation of gamma-ray flares from blazar 0836+710 in 2011, following a period of quiescence, offered an opportunity to study correlated activity at different wavelengths for a high-redshift (z=2.218) active galactic nucleus. Optical and radio monitoring, plus Fermi-LAT gamma-ray monitoring provided 2008-2012 coverage, while Swift offered auxiliary optical, ultraviolet, and X-ray information. Other contemporaneous observations were used to construct a broad-band spectral energy distribution.
Utilizing the latest and the most sensitive radio and optical catalogs, we completed a new blazar candidate catalog, Blazar Radio and Optical Survey (BROS), which includes 88211 sources located at decl. {delta}>-40{deg} and outside the galactic plane (|b|>10{deg}). We list compact flat-spectrum radio sources of {alpha}>-0.6 ({alpha} is defined as F_{nu}_{prop.to}{nu}^{alpha}^) from 0.15GHz TGSS to 1.4GHz NVSS catalogs. We further identify optical counterparts of the selected sources by cross-matching with Pan-STARRS1 photometric data. Color-color and color-magnitude plots for the selected BROS sources clearly show two distinct populations, a "quasar-like" population consisting of both flat-spectrum radio quasars and BL Lac type objects. On the other hand, an "elliptical-like" population of mostly BL Lac type objects is buried in the elliptical galaxy. The latter population is also reported in previous catalogs, but the BROS catalog provided a new larger sample of this population, due to the lower radio flux threshold of our selection. Model calculations show that the "elliptical-like" population consists of elliptical galaxies located at redshift z<=0.5, which is also supported by the logN-logS distribution of the power-law index of 1.49+/-0.05. This BROS catalog is useful for identifying the electromagnetic counterparts of ultra-high-energy cosmic rays and PeV neutrinos recently detected by IceCube, as well as nearby BL Lac objects detectable by future high-sensitivity TeV telescopes, such as the Cherenkov Telescope Array.
Accretion rates and their correlation with cosmological redshifts for a sample of blazars and Seyfert galaxies are presented. The sample includes 77 blazars (28 FSRQs, 26 LBLs, and 23 HBLs) and 60 Seyfert galaxies, of which the extended spectral energy distribution information and redshifts are available. Within the framework of accreting black holes, the accretion rates for these sources were estimated based on their bolometric luminosities.
