766 research outputs found
Fertility and rural electrification in Bangladesh
We use a panel dataset from Bangladesh to examine the relationship between fertility and the adoption of electricity with the latter instrumented by infrastructure development and the quality of service delivery. We find that the adoption of electricity reduces fertility, and this impact is more pronounced when the household already has two or more children. This observation can be explained by a simple household model of time use, in which adoption of electricity affects only the optimal number of children but not necessarily current fertility behavior if the optimal number has not yet been reached
Fertility and rural electrification in Bangladesh
Ministry of Education, Singapore under its Academic Research Funding Tier
Clustering Properties of Low-Luminosity Star-Forming galaxies at z = 0.24 and 0.40 in the Subaru Deep Field
We present our analysis on the clustering properties of star-forming galaxies
selected by narrow-band excesses in the Subaru Deep Field. Specifically we
focus on Halpha emitting galaxies at z = 0.24 and z = 0.40 in the same field,
to investigate possible evolutionary signatures of clustering properties of
star-forming galaxies. Based on the analysis on 228 Halpha emitting galaxies
with 39.8 < log L(Halpha) < 40.8 at z = 0.40, we find that their two-point
correlation function is estimated as xi = (r/1.62^{+0.64}_{-0.50} Mpc)^{-1.84
+/- 0.08}. This is similar to that of Halpha emitting galaxies in the same
Halpha luminosity range at z = 0.24, xi = (r/1.88^{+0.60}_{-0.49} Mpc)^{-1.89
+/- 0.07}. These correlation lengths are smaller than those for the brighter
galaxy sample studied by Meneux et al. (2006) in the same redshift range. The
evolution of correlation length between z = 0.24 and z = 0.40 is interpreted by
the gravitational growth of the dark matter halos.Comment: 16 pages, 7 figures, PASJ, Vol.60, No.6, in pres
Impact of electrification on children\u27s nutritional status in rural Bangladesh
We offer micro-econometric evidence for a positive impact of rural electrification on the nutritional status of children under five as measured by height-for-age Z-score (HAZ) in rural Bangladesh. In most estimates, access to electricity is found to improve HAZ by more than 0.15 points and this positive impact comes from increased wealth and reduced fertility, even though the evidence for the latter is weak. We also analyze the causal channels through the local health facility and exposure to television. We find no evidence for the presence of the former channel and mixed evidence for the latter
A New Insight into Electron Acceleration Properties from Theoretical Modeling of Double-Peaked Radio Light Curves in Core-Collapse Supernovae
It is recognized that some core-collapse supernovae (SNe) show a
double-peaked radio light curve within a few years since the explosion. A shell
of circumstellar medium (CSM) detached from the SN progenitor has been
considered to play a viable role in characterizing such a re-brightening of
radio emission. Here, we propose another mechanism that can give rise to the
double-peaked radio light curve in core-collapse SNe. The key ingredient in the
present work is to expand the model for the evolution of the synchrotron
spectral energy distribution (SED) to a generic form, including fast and slow
cooling regimes, as guided by the widely-accepted modeling scheme of gamma-ray
burst afterglows. We show that even without introducing an additional CSM
shell, the radio light curve would show a double-peaked morphology when the
system becomes optically thin to synchrotron self-absorption at the
observational frequency during the fast cooling regime. We can observe this
double-peaked feature if the transition from fast cooling to slow cooling
regime occurs during the typical observational timescale of SNe. This situation
is realized when the minimum Lorentz factor of injected electrons is initially
large enough for the non-thermal electrons' SED to be discrete from the thermal
distribution. We propose SN 2007bg as a special case of double-peaked radio SNe
that can be explained by the presented scenario. Our model can serve as a
potential diagnostic for electron acceleration properties in SNe.Comment: 16 pages, 8 figures, submitted to Ap
Large-scale Filamentary Structure around the Protocluster at Redshift z=3.1
We report the discovery of a large-scale coherent filamentary structure of
Lyman alpha emitters in a redshift space at z=3.1. We carried out spectroscopic
observations to map the three dimensional structure of the belt-like feature of
the Lyman alpha emitters discovered by our previous narrow-band imaging
observations centered on the protocluster at z=3.1. The feature was found to
consist of at least three physical filaments connecting with each other. The
result is in qualitative agreement with the prediction of the 'biased'
galaxy-formation theories that galaxies preferentially formed in large-scale
filamentary or sheet-like mass overdensities in the early Universe. We also
found that the two known giant Lyman alpha emission-line nebulae showing high
star-formation activities are located near the intersection of these filaments,
which presumably evolves into a massive cluster of galaxies in the local
Universe. This may suggest that massive galaxy formation occurs at the
characteristic place in the surrounding large-scale structure at high redshift.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter
Discovery of a Gravitationally Lensed Quasar from the Sloan Digital Sky Survey: SDSS J133222.62+034739.9
We report the discovery of the two-image gravitationally lensed quasar SDSS
J133222.62+034739.9 (SDSS J1332+0347) with an image separation of
Delta_theta=1.14". This system consists of a source quasar at z_s=1.445 and a
lens galaxy at z_l=0.191. The agreement of the luminosity, ellipticity and
position angle of the lens galaxy with those expected from lens model confirms
the lensing hypothesis.Comment: 16 pages, 4 figures, the Astronomical Journal accepte
Subaru Hyper Suprime-Cam Survey for An Optical Counterpart of GW170817
We perform a -band survey for an optical counterpart of a binary neutron
star coalescence GW170817 with Subaru/Hyper Suprime-Cam. Our untargeted
transient search covers deg corresponding to the credible
region of GW170817 and reaches the completeness magnitude of mag
on average. As a result, we find 60 candidates of extragalactic transients,
including J-GEM17btc (a.k.a. SSS17a/DLT17ck). While J-GEM17btc is associated
with NGC 4993 that is firmly located inside the 3D skymap of GW170817, the
other 59 candidates do not have distance information in the GLADE v2 catalog or
NASA/IPAC Extragalactic Database (NED). Among 59 candidates, 58 are located at
the center of extended objects in the Pan-STARRS1 catalog, while one candidate
has an offset. We present location, -band apparent magnitude, and time
variability of the candidates and evaluate the probabilities that they are
located inside of the 3D skymap of GW170817. The probability for J-GEM17btc is
being much higher than those for the other 59 candidates
(). Furthermore, the possibility, that at
least one of the other 59 candidates is located within the 3D skymap, is only
. Therefore, we conclude that J-GEM17btc is the most-likely and
distinguished candidate as the optical counterpart of GW170817.Comment: 14 pages, 9 figures. Accepted for publication in PASJ (Publications
of the Astronomical Society of Japan
A Keck/DEIMOS Spectroscopy of Lyman Alpha Blobs at Redshift z=3.1
We present the results of an intermediate resolution (~2 angstrom)
spectroscopy of a sample of 37 candidate Lyman alpha blobs and emitters at
redshift z=3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The
emission lines are detected for all the 37 objects and have variety in their
line profiles. The Lyman alpha velocity widths (FWHM) of the 28 objects with
higher quality spectra, measured by fitting a single Gaussian profile, are in
the range of 150 - 1700 km/s and correlate with the Lyman alpha spatial
extents. All the 12 Lyman alpha blobs (>16 arcsec^2) have large velocity widths
of > 500 km/s. While there are several possible physical interpretations of the
Lyman alpha velocity widths (motion of gravitationally-bound gas clouds,
inflows, merging of clumps, or outflows from superwinds), the large velocity
widths of the Lyman alpha blobs suggest that they are the sites of massive
galaxy formation. If we assume gravitationally-bound gas clouds, the dynamical
masses of the Lyman alpha blobs are estimated to be ~10^12 - 10^13 Msun. Even
for the case of outflows, the outflow velocities are likely to be the same
order of the rotation velocities as inferred from the observational evidence
for local starburst galaxies.Comment: Accepted for publication in ApJ
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