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.
Based on a large Fermi blazar sample, the blazar sequence (synchrotron peak frequency {nu}_peak_ versus synchrotron peak luminosity L_peak_) is revisited. It is found that there is significant anticorrelation between {nu}_peak_ and L_peak_ for blazars. However, after Doppler correction the anticorrelation disappears. The jet cavity power (P_jet_) is estimated from the extended radio luminosity so that it is free of beaming effects. We find that there are significant anticorrelations between P_jet_ and the beam-corrected {nu}_peak_' for both blazars and radio galaxies, which supports the blazar sequence and the unification of blazars and radio galaxies (an alternative relationship is the correlation between jet power and {gamma}-ray photon index).
Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marcha et al. (1996MNRAS.281..425M). We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS, Cat. <J/AJ/115/1253> and <J/MNRAS/323/757>) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]{lambda}5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]{lambda}5007-[OII]{lambda}3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars.
