1,205 research outputs found
Extended X-ray emission around four 3C quasars at 0.55<z<0.75 observed with Chandra
We report on the detection of a soft spatially-extended component of X-ray
emission around four intermediate-redshift 3C quasars observed with Chandra:
3C254, 3C263, 3C275.1 and 3C281. The bolometric luminosity of this emission
ranges over 0.3-1.6 times 10^{44}erg/s, and extends to lengthscales of over 350
kpc at the redshift of the quasar. The X-rays are most likely thermal emission
from the intracluster medium of a cluster of galaxies around each quasar, which
provides the working surface for the powerful radio lobes. Some X-ray emission
is also seen to be associated with the radio plasma.Comment: 8 pages, 4 panelled figures, MNRAS in pres
Spectral optical monitoring of 3C390.3 in 1995-2007: I. Light curves and flux variation of the continuum and broad lines
Here we present the results of the long-term (1995-2007) spectral monitoring
of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the
double peaked broad emission lines, usually assumed to be emitted from an
accretion disk. To explore dimensions and structure of the BLR, we analyze the
light curves of the broad H and H line fluxes and the continuum
flux. In order to find changes in the BLR, we analyze the H and
H line profiles, as well as the change in the line profiles during the
monitoring period. First we try to find a periodicity in the continuum and
H light curves, finding that there is a good chance for quasi-periodical
oscillations. Using the line shapes and their characteristics (as e.g. peaks
separation and their intensity ratio, or FWHM) of broad H and H
lines, we discuss the structure of the BLR. Also, we cross-correlate the
continuum flux with H and H lines to find dimensions of the BLR.
We found that during the monitoring period the broad emission component of the
H and H lines, and the continuum flux varied by a factor of
4-5. Also, we detected different structure in the line profiles of
H and H. It seems that an additional central component is
present and superposed to the disk emission. In the period of high activity
(after 2002), H became broader than H and red wing of H
was higher than the one of H. We found time lags of 95 days
between the continuum and H flux, and about 120 days between the
continuum and H flux. Variation in the line profiles, as well as
correlation between the line and continuum flux during the monitoring period is
in the favor of the disk origin of the broad lines with the possible
contribution of some additional region and/or some kind of perturbation in the
disk.Comment: 32 pages, accepted to A&A, typos correcte
An allelic series of spontaneous Rorb mutant mice exhibit a gait phenotype, changes in retina morphology and behavior, and gene expression signatures associated with the unfolded protein response.
The Retinoid-related orphan receptor beta (RORβ) gene encodes a developmental transcription factor and has 2 predominant isoforms created through alternative first exon usage; one specific to the retina and another present more broadly in the central nervous system, particularly regions involved in sensory processing. RORβ belongs to the nuclear receptor family and plays important roles in cell fate specification in the retina and cortical layer formation. In mice, loss of RORβ causes disorganized retina layers, postnatal degeneration, and production of immature cone photoreceptors. Hyperflexion or high-stepping of rear limbs caused by reduced presynaptic inhibition by Rorb-expressing inhibitory interneurons of the spinal cord is evident in RORβ-deficient mice. RORβ variants in patients are associated with susceptibility to various neurodevelopmental conditions, primarily generalized epilepsies, but including intellectual disability, bipolar, and autism spectrum disorders. The mechanisms by which RORβ variants confer susceptibility to these neurodevelopmental disorders are unknown but may involve aberrant neural circuit formation and hyperexcitability during development. Here we report an allelic series in 5 strains of spontaneous Rorb mutant mice with a high-stepping gait phenotype. We show retinal abnormalities in a subset of these mutants and demonstrate significant differences in various behavioral phenotypes related to cognition. Gene expression analyses in all 5 mutants reveal a shared over-representation of the unfolded protein response and pathways related to endoplasmic reticulum stress, suggesting a possible mechanism of susceptibility relevant to patients
The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity
We analyze the neutron electric dipole moment (EDM) in the Minimal
Supersymmetric Model with explicit R-parity violating terms. The leading
contribution to the EDM occurs at the 2-loop level and is dominated by the
chromoelectric dipole moments of quarks, assuming there is no tree-level
mixings between sleptons and Higgs bosons or between leptons and gauginos.
Based on the experimental constraint on the neutron EDM, we set limits on the
imaginary parts of complex couplings and
due to the virtual b-loop or tau-loop.Comment: final manuscript to appear in Phys. Rev. D, 15 pages, latex, 4
figures include
OGLE-2012-BLG-0455/MOA-2012-BLG-206: Microlensing event with ambiguity in planetary interpretations caused by incomplete coverage of planetary signal
Characterizing a microlensing planet is done from modeling an observed
lensing light curve. In this process, it is often confronted that solutions of
different lensing parameters result in similar light curves, causing
difficulties in uniquely interpreting the lens system, and thus understanding
the causes of different types of degeneracy is important. In this work, we show
that incomplete coverage of a planetary perturbation can result in degenerate
solutions even for events where the planetary signal is detected with a high
level of statistical significance. We demonstrate the degeneracy for an
actually observed event OGLE-2012-BLG-0455/MOA-2012-BLG-206. The peak of this
high-magnification event exhibits very strong deviation
from a point-lens model with for data sets with a
total number of measurement 6963. From detailed modeling of the light curve, we
find that the deviation can be explained by four distinct solutions, i.e., two
very different sets of solutions, each with a two-fold degeneracy. While the
two-fold (so-called "close/wide") degeneracy is well-understood, the degeneracy
between the radically different solutions is not previously known. The model
light curves of this degeneracy differ substantially in the parts that were not
covered by observation, indicating that the degeneracy is caused by the
incomplete coverage of the perturbation. It is expected that the frequency of
the degeneracy introduced in this work will be greatly reduced with the
improvement of the current lensing survey and follow-up experiments and the
advent of new surveys.Comment: 5 pages, 3 figures, ApJ accepte
The Science Case for an Extended Spitzer Mission
Although the final observations of the Spitzer Warm Mission are currently
scheduled for March 2019, it can continue operations through the end of the
decade with no loss of photometric precision. As we will show, there is a
strong science case for extending the current Warm Mission to December 2020.
Spitzer has already made major impacts in the fields of exoplanets (including
microlensing events), characterizing near Earth objects, enhancing our
knowledge of nearby stars and brown dwarfs, understanding the properties and
structure of our Milky Way galaxy, and deep wide-field extragalactic surveys to
study galaxy birth and evolution. By extending Spitzer through 2020, it can
continue to make ground-breaking discoveries in those fields, and provide
crucial support to the NASA flagship missions JWST and WFIRST, as well as the
upcoming TESS mission, and it will complement ground-based observations by LSST
and the new large telescopes of the next decade. This scientific program
addresses NASA's Science Mission Directive's objectives in astrophysics, which
include discovering how the universe works, exploring how it began and evolved,
and searching for life on planets around other stars.Comment: 75 pages. See page 3 for Table of Contents and page 4 for Executive
Summar
Halogen Oxidation Reactions of (C5Ph5)Cr(CO)3 and Lewis Base Addition To [(C5Ph5)Cr(μ-X)X]2: Electrochemical, Magnetic, and Raman Spectroscopic Characterization of [(C5Ph5)CrX2]2 and (C5Ph5)CrX2(THF) (X = Cl, Br, I). X-ray Crystal Structure of [(C5Ph5)Cr(μ-Cl)Cl]2
The 17-electron complex (C5Ph5)Cr(CO)3 reacts with halogens (C6H5I•Cl2, Br2, and I2) in C6H6 to yield the dimeric oxidation products [(C5Ph5)Cr(m-X)X]2 as thermally stable solids. Reactions with other chlorinating agents similarly yield [(C5Ph5)CrCl2]2. An X-ray crystal structure of [(C5Ph5)Cr(m-Cl)Cl]2 was obtained. The magnetic properties of the Cl2 bridged dimer have been determined and modeled using the usual isotropic hamiltonian which yields J/k = –30 K. Low-temperature (77 K) Raman spectra of solid [(C5Ph5)CrX2]2 (X = Cl, I) allow assignments to be made for the metal-ring and metal halogen stretching modes in the low frequency region (\u3c 600 cm-1). Tetrahydrofuran (THF) cleaves these dimers to yield complexes of the form (C5Ph5)CrX2(THF)
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