605,518 research outputs found
The 100 micron surveys in the Northern and Southern Hemispheres
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
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
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.
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
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?
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
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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