605,518 research outputs found

    The 100 micron surveys in the Northern and Southern Hemispheres

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    Partial surveys in the far infrared in the Northern and Southern Hemispheres have covered 40% of the galactic equator and assorted regions away from the galactic plane. Approximately 120 100-micron objects are known. These are distributed extensively in galactic longitude and concentrated within + or - two degrees in galactic latitude. From this information, some general conclusions can be drawn about the sensitivity and coverage required for a general sky survey in the far infrared

    The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension

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    We present a re-reduction and expansion of the Bolocam Galactic Plane Survey, first presented by Aguirre et al. (2011) and Rosolowsky et al. (2010). The BGPS is a 1.1 mm survey of dust emission in the Northern galactic plane, covering longitudes -10 < \ell < 90 and latitudes |b| < 0.5 with a typical 1-\sigma RMS sensitivity of 30-100 mJy in a 33" beam. Version 2 of the survey includes an additional 20 square degrees of coverage in the 3rd and 4th quadrants and 2 square degrees in the 1st quadrant. The new data release has improved angular recovery, with complete recovery out to 80" and partial recovery to 300", and reduced negative bowls around bright sources resulting from the atmospheric subtraction process. We resolve the factor of 1.5 flux calibration offset between the v1.0 data release and other data sets and determine that there is no offset between v2.0 and other data sets. The v2.0 pointing accuracy is tested against other surveys and demonstrated to be accurate and an improvement over v1.0. We present simulations and tests of the pipeline and its properties, including measurements of the pipeline's angular transfer function. The Bolocat cataloging tool was used to extract a new catalog, which includes 8594 sources, with 591 in the expanded regions. We have demonstrated that the Bolocat 40" and 80" apertures are accurate even in the presence of strong extended background emission. The number of sources is lower than in v1.0, but the amount of flux and area included in identified sources is larger.Comment: 36 pages, 16 figures, accepted to ApJS. Data available from http://irsa.ipac.caltech.edu/data/BOLOCAM_GPS

    Ultraviolet-Selected Field and Pre-Main-Sequence Stars Towards Taurus and Upper Scorpius

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    We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56 square degrees near the Taurus T association and 12 square degrees along the northern edge of the Upper Scorpius OB association. We combined photometry in the GALEX FUV and NUV bands with data from the Two Micron All Sky Survey to identify candidate young (<100 Myr old) stars as those with an ultraviolet excess relative to older main sequence stars. Follow-up spectroscopy of a partial sample of these candidates suggest 5 new members of Taurus, with 8-20 expected from additional observations, and 5 new members of Upper Scorpius, with 3-6 expected from additional observations. These candidate new members appear to represent a distributed, non-clustered population in either region, although our sample statistics are as of yet too poor to constrain the nature or extent of this population. Rather, our study demonstrates the ability of GALEX observations to identify young stellar populations distributed over a wide area of the sky. We also highlight the necessity of a better understanding of the Galactic ultraviolet source population to support similar investigations. In particular, we report a large population of stars with an ultraviolet excess but no optical indicators of stellar activity or accretion, and briefly argue against several interpretations of these sources.Comment: 46 pages, 16 figures, 13 tables; Accepted to the Astronomical Journa

    Informal Labour and Credit Markets: A Survey.

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    This paper reviews the literature on the informal economy, focusing first on empirical findings and then on existing approaches to modelling informality within both partial and general equilibrium environments. We concentrate on labour and credit markets, since these tend to be most affected by informality. The phenomenon is particularly important in emerging and other developing economies, given their high degrees of informal labour and financial services and the implications these have for the effectiveness of macroeconomic policy. We emphasize the need for dynamic general equilibrium (DGE) and ultimately dynamic stochastic general equilibrium (DSGE) models for a full understanding of the costs, benefits and policy implications of informality. The survey shows that the literature on informality is quite patchy, and that there are several unexplored areas left for research.Informal economy ; Labour market ; Search-matching models

    Informal Labour and Credit Markets: A Survey

    Get PDF
    This paper reviews the literature on the informal economy, focusing first on empirical findings and then on existing approaches to modelling informality within both partial and general equilibrium environments. We concentrate on labour and credit markets, since these tend to be most affected by informality. The phenomenon is particularly important in emerging and other developing economies, given their high degrees of informal labour and financial services and the implications these have for the effectiveness of macroeconomic policy. We emphasize the need for dynamic general equilibrium (DGE) and ultimately dynamic stochastic general equilibrium (DSGE) models for a full understanding of the costs, benefits and policy implications of informality. The survey shows that the literature on informality is quite patchy, and that there are several unexplored areas left for research. JEL Classification: J65, E24, E26, E32Informal economy, labour market, search-matching models

    A dipole anisotropy of galaxy distribution: Does the CMB rest-frame exist in the local universe?

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    The peculiar motion of the Earth causes a dipole anisotropy modulation in the distant galaxy distribution due to the aberration effect. However, the amplitude and angular direction of the effect is not necessarily the same as those of the cosmic microwave background (CMB) dipole anisotropy due to the growth of cosmic structures. In other words exploring the aberration effect may give us a clue to the horizon-scale physics perhaps related to the cosmic acceleration. In this paper we develop a method to explore the dipole angular modulation from the pixelized galaxy data on the sky properly taking into account the covariances due to the shot noise and the intrinsic galaxy clustering contamination as well as the partial sky coverage. We applied the method to the galaxy catalogs constructed from the Sloan Digital Sky Survey (SDSS) Data Release 6 data. After constructing the four galaxy catalogs that are different in the ranges of magnitudes and photometric redshifts to study possible systematics, we found that the most robust sample against systematics indicates no dipole anisotropy in the galaxy distribution. This finding is consistent with the expectation from the concordance Lambda-dominated cold dark matter model. Finally we argue that an almost full-sky galaxy survey such as LSST may allow for a significant detection of the aberration effect of the CMB dipole having the precision of constraining the angular direction to ~ 20 degrees in radius. Assuming a hypothetical LSST galaxy survey, we find that this method can confirm or reject the result implied from a stacked analysis of the kinetic Sunyaev-Zel'dovich effect of X-ray luminous clusters in Kashlinsky et al. (2008,2009) if the implied cosmic bulk flow is not extended out to the horizon.Comment: 20 pages, 11 figures; 24 pages, added a couple of references and 2 figures. Revised version in response to the referee's comments. Resubmitted to Phys. Rev.

    Photometry of the UWISH2 extended H2 source catalogue

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    The UKIRT Widefield Infrared Survey for H2 (UWISH2) is a large, unbiased survey of extended H2 emission sources, using the 1-0 S(1) emission line at 2.122?m. It covers 209 square degrees of the Galactic Plane (GP) between l ? 357° to l ? 66° and b ? ±1.5°. UWISH2 further covers high column density regions in Cygnus and Auriga, covering approximately 42 and 35.5 square degrees respectively and leading to a total survey coverage of ? 286.5 square degrees. As part of the UWISH2 team, I have performed the photometry for 33200 individual H2 features, which have been found to compose ~ 700 H2 jets and outflows, 284 planetary nebulae (PNe), 30 supernova remnants (SNRs) and ~ 1300 photo-dissociation regions (PDRs). About 60% of PNe are newly discovered candidates. Using H2 emission as a tracer for star formation, I find that the majority of H2 flux is located in the lower Galactic longitudes for jet and PDR features, indicating increased star formation activity. I have also observed partial concentrations of high H2 flux at higher Galactic longitudes in the GP from jet features but not PDR features, indicating a lack of high-mass star formation at this region. I offer two methods of photometry: the 'total flux' photometry and the 'median surface brightness times area' photometry. Upon comparing the ratios of the fluxes from both photometries for each feature, I find good agreement (full catalogue: ~ 97% in a 100% deviation and ~ 82% in a 20% deviation) for all feature classes except jets, and recommend the median surface brightness times area photometry for all feature types except jets, which should use total flux photometry. Finally, I have calculated the signal-to-noise ratios for individual features, finding the median value for the entire survey to be approximately 15 when using the feature area
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