2,195 research outputs found
Optical Spectropolarimetry of SN 2002ap: High Velocity Asymmetric Explosion
We present spectropolarimetry of the Type Ic supernova SN 2002ap and give a
preliminary analysis: the data were taken at two epochs, close to and one month
later than the visual maximum (2002 February 8). In addition we present June 9
spectropolarimetry without analysis. The data show the development of linear
polarization. Distinct polarization profiles were seen only in the O I \lambda
7773 multiplet/Ca II IR triplet absorption trough at maximum light and in the
Ca II IR triplet absorption trough a month later, with the latter showing a
peak polarization as high as ~2 %. The intrinsic polarization shows three clear
position angles: 80 degs for the February continuum, 120 degs for the February
line feature, and 150 degs for the March data. We conclude that there are
multiple asymmetric components in the ejecta. We suggest that the supernova has
a bulk asymmetry with an axial ratio projected on the sky that is different
from 1 by of order 10 %. Furthermore, we suggest very speculatively that a high
velocity ejecta component moving faster than ~0.115c (e.g., a jet) contributes
to polarization in the February epoch.Comment: 7 pages, 3 figures, accepted for publication in the Astrophysical
Journal (Letters
X-ray Diagnostics of Thermal Conditions of the Hot Plasmas in the Centaurus Cluster
X-ray data of the Centaurus cluster, obtained with {\it XMM-Newton} for 45
ksec, were analyzed. Deprojected EPIC spectra from concentric thin shell
regions were reproduced equally well by a single-phase plasma emission model,
or by a two-phase model developed by {\it ASCA}, both incorporating cool
(1.7--2.0 keV) and hot ( keV) plasma temperatures. However, EPIC
spectra with higher statistics, accumulated over 3-dimentional thick shell
regions, were reproduced better by the two-phase model than by the singe-phase
one. Therefore, hot and cool plasma phases are inferred to co-exist in the
cluster core region within kpc. The iron and silicon abundances of
the plasma were reconfirmed to increase significantly towards the center, while
that of oxygen was consistent with being radially constant. The implied
non-solar abundance ratios explains away the previously reported excess X-ray
absorption from the central region. Although an additional cool (
keV) emission was detected within kpc of the center, the RGS data
gave tight upper limits on any emission with a tempeartures below
keV. These results are compiled into a magnetosphere model, which interprets
the cool phase as confined within closed magnetic loops anchored to the cD
galaxy. When combined with so-called Rosner-Tucker-Vaiana mechanism which
applies to solar coronae, this model can potentially explain basic properties
of the cool phase, including its temperature and thermal stability.Comment: 53 pages, 11 figures, accepted for publication in Astrophysical
Journa
Subaru Deep Survey V. A Census of Lyman Break Galaxies at z=4 and 5 in the Subaru Deep Fields: Photometric Properties
(abridged) We investigate photometric properties of Lyman Break Galaxies
(LBGs) at z=3.5-5.2 based on large samples of 2,600 LBGs detected in deep
(i'~27) and wide-field (1,200 arcmin^2) images taken in the Subaru Deep Field
(SDF) and the Subaru/XMM Deep Field (SXDF). The selection criteria for the LBG
samples are examined with 85 spectroscopically identified objects and by Monte
Carlo simulations. We find in the luminosity functions of LBGs (i) that the
number density of bright galaxies (M_{1700}<-22; corresponding to
SFR_{corr}>100 Msolar yr^{-1}) decreases significantly from z=4 to 5 and (ii)
that the faint-end slope of the luminosity function may become steeper towards
higher redshifts. We estimate dust extinction of z=4 LBGs with M<M^* from UV
slopes, and obtain E(B-V)=0.15+/-0.03 as the mean value. The dust extinction
remains constant with apparent luminosity, but increases with intrinsic
luminosity. We find no evolution in dust extinction between LBGs at z=3 and 4.
We investigate the evolution of UV-luminosity density at 1700A, rho, and find
that rho does not significantly change from z=3 to z=5, i.e.,
rho(z=4)/rho(z=3)=1.0+/-0.2 and rho(z=5)/rho(z=3)=0.8+/-0.4, thus the cosmic
star-formation rate (SFR) density remains constant. We find that the stellar
mass density estimated from the cosmic SFR is consistent with those derived
directly from the stellar mass function at z=0-1, but exceeds those at z~3 by a
factor of 3. We find that the ratio of the UV-luminosity density of Ly-a
emitters (LAEs) to that of LBGs is ~60% at z=5, and thus about a half of the
star formation at z=5 probably occurs in LAEs. We obtain a constraint on the
escape fraction of UV-ionizing photons produced by LBGs, f_{esc}>~0.13.Comment: 41 pages, 22 figures, ApJ in press. Paper with high resolution
figures is available at
http://hikari.astron.s.u-tokyo.ac.jp/~ouchi/work/astroph/SDS_V_VI/SDS_V.pdf
(PDF
The role of the CNR1 gene in schizophrenia: a systematic review including unpublished data
Objective: Schizophrenia is a multifactorial disorder. It is known that a combination of extensive multiple common alleles may be involved in its etiology, each contributing with a small to moderate effect, and, possibly, some rare alleles with a much larger effect size. We aimed to perform a systematic review of association studies between schizophrenia (and its subphenotypes) and polymorphisms in the CNR1 gene, which encodes cannabinoid receptors classically implicated in schizophrenia pathophysiology, as well as to present unpublished results of an association study in a Brazilian population. Methods: Two reviewers independently searched for eligible studies and extracted outcome data using a structured form. Papers were retrieved from PubMed and ISI Web of Knowledge using the search term schizophrenia in combination with CNR1 or CB1 or cannabinoid receptor. Twenty-four articles met our inclusion criteria. We additionally present data from a study of our own comparing 182 patients with schizophrenia and 244 healthy controls. Results: No consistent evidence is demonstrated. Conclusion: Some seemingly positive association studies stress the need for further investigations of the possible role of endocannabinoid genetics in schizophrenia.Fundacao de Amparo e Pesquisa do Estado de Sao Paulo (FAPESP) [2010/08968-6, 2011/50740-5, 2011/00030-1]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Fundacao SafraFundacao ABADSUniv Fed Sao Paulo UNIFESP, Dept Psiquiatria, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Lab Interdisciplinar Neurociencias Clin LiNC, Sao Paulo, SP, BrazilIrmandade Santa Casa Misericordia Sao Paulo, Dept Psiquiatria, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Morfol & Genet, Sao Paulo, SP, BrazilUniv Fed Sao Paulo UNIFESP, Dept Psiquiatria, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Lab Interdisciplinar Neurociencias Clin LiNC, Sao Paulo, SP, BraziWeb of Scienc
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