140 research outputs found
The soft X-ray polarization in obscured AGN
The soft X-ray emission in obscured active galactic nuclei (AGN) is dominated
by emission lines, produced in a gas photoionized by the nuclear continuum and
likely spatially coincident with the optical narrow line region (NLR). However,
a fraction of the observed soft X-ray flux appears like a featureless power law
continuum. If the continuum underlying the soft X-ray emission lines is due to
Thomson scattering of the nuclear radiation, it should be very highly
polarized. We calculated the expected amount of polarization assuming a simple
conical geometry for the NLR, combining these results with the observed
fraction of the reflected continuum in bright obscured AGN.Comment: 6 pages, 3 figures, to appear in 'X-ray Polarimetry: A New Window in
Astrophysics', edited by R. Bellazzini, E. Costa, G. Matt and G. Tagliaferr
The NuSTAR view of the Seyfert Galaxy HE 0436-4717
We present the multi epoch spectral analysis of HE 0436-4717, a bright
Seyfert 1 galaxy serendipitously observed by the high energy satellite NuSTAR
four times between December 2014 and December 2015. The source flux shows
modest variability within each pointing and among the four observations.
Spectra are well modelled in terms of a weakly variable primary power law with
constant photon index (=2.010.08). A constant narrow \ion{Fe}
K emission line suggests that this feature has an origin far from the
central black hole, while a broad relativistic component is not required by the
data. The Compton reflection component is also constant in flux with a
corresponding reflection fraction R=0.7. The iron abundance is
compatible with being Solar (A=1.2), and a lower limit
for the high energy cut-off E>280 keV is obtained. Adopting a
self-consistent model accounting for a primary Comptonized continuum, we obtain
a lower limit for the hot corona electron temperature kT>65 keV and a
corresponding upper limit for the coronal optical depth of <1.3. The
results of the present analysis are consistent with the locus of local Seyfert
galaxies in the kT- and temperature-compactness diagrams.Comment: accepted for publication in A&
HST unveils a compact mildly relativistic Broad Line Region in the candidate true type 2 NGC 3147
NGC 3147 has been considered the best case of a true type 2 AGN: an
unobscured AGN, based on the unabsorbed compact X-ray continuum, which lacks a
broad line region (BLR). However, the very low luminosity of NGC 3147 implies a
compact BLR, which produces very broad lines, hard to detect against the
dominant background host galaxy. Narrow (0.1"x0.1") slit HST spectroscopy
allowed us to exclude most of the host galaxy light, and revealed an H
line with an extremely broad base (FWZI km s). The line
profile shows a steep cutoff blue wing and an extended red wing, which match
the signature of a mildly relativistic thin accretion disk line profile. It is
indeed well fit with a nearly face on thin disk, at , with an
inner radius at r, which matches the prediction of
r from the relation. This
result questions the very existence of true type 2 AGN. Moreover, the detection
of a thin disk, which extends below 100 r in an
system, contradicts the current view of the accretion flow configuration at
extremely low accretion rates.Comment: 6 pages, 3 figures, accepted for publication in MNRAS Letter
Towards precision tests of general relativity with black hole X-ray reflection spectroscopy
Astrophysical black hole systems are the ideal laboratories for testing
Einstein's theory of gravity in the strong field regime. We have recently
developed a framework which uses the reflection spectrum of black hole systems
to perform precision tests of general relativity by testing the Kerr black hole
hypothesis. In this paper, we analyze XMM-Newton and NuSTAR observations of the
supermassive black hole in the Seyfert 1 galaxy MCG-06-30-15 with our disk
reflection model. We consider the Johannsen metric with the deformation
parameters and , which quantify deviations from the
Kerr metric. For , we obtain the black hole spin and . For , we obtain
and . The Kerr solution is
recovered for . Thus, our results include the
Kerr solution within statistical uncertainties. Systematic uncertainties are
difficult to account for, and we discuss some issues in this regard.Comment: 10 pages, 7 figures. v2: title slightly changed, arXiv version
shorter than published versio
Olive mill wastewater phenolic concentrate as natural antioxidant against lipid-protein oxidative deterioration in chicken meat during storage
NGC 2992: The interplay between the multiphase disk, wind and radio bubbles
We present an analysis of the gas kinematics in NGC 2992, based on VLT/MUSE,
ALMA and VLA data, aimed at characterising the disk, the wind and their
interplay in the cold molecular and warm ionised phases. CO(2-1) and H arise from a multiphase disk with inclination 80 deg and radii 1.5 and
1.8 kpc, respectively. We find that the velocity dispersion of the cold
molecular phase is consistent with that of star forming galaxies at the same
redshift, except in the inner 600 pc region, and in the region between the cone
walls and the disk. This suggests that a disk-wind interaction locally boosts
the gas turbulence. We detect a clumpy ionised wind distributed in two wide
opening angle ionisation cones reaching scales of 7 kpc. The [O III] wind
expands with velocity exceeding -1000 km/s in the inner 600 pc, a factor of 5
larger than the previously reported wind velocity. Based on spatially resolved
electron density and ionisation parameter maps, we infer an ionised outflow
mass of , and a
total ionised outflow rate of \sfr. We detected
clumps of cold molecular gas located above and below the disk reaching maximum
projected distances and velocities of 1.7 kpc and 200 km/s, respectively. On
these scales, the wind is multiphase, with a fast ionised component and a
slower molecular one, and a total mass of , of which the molecular component carries the bulk of the mass.
The dusty molecular outflowing clumps and the turbulent ionised gas are located
at the edges of the radio bubbles, suggesting that the bubbles interact with
the surrounding medium through shocks. We detect a dust reservoir co-spatial
with the molecular disk, with a cold dust mass .Comment: 19 pages, 17 figures, 6 tables; Accepted by A&
Gene co-expression networks in liver and muscle transcriptome reveal sex-specific gene expression in lambs fed with a mix of essential oils
Background: Essential oil (EO) dietary supplementation is a new strategy to improve animal health. EO compounds have antiparasitic, antimicrobial, antiviral, antimycotic, antioxidant and anti-inflammatory proprieties. Nutrigenomics investigations represent innovative approaches in understanding the relation between diet effect and gene expression related to the animal performance. Few nutrigenomics studies have used a high-throughput RNA-Sequencing (RNA-Seq) approach, despite great potential of RNA-Seq data in gene expression quantification and in co-expression network analyses. Our aim is to use the potential of RNA-Sequencing data in order to evaluate the effect of an EO supplementary diet on gene expression in both lamb liver and muscle. Results: Using a treatment and sex interaction model, 13 and 4 differentially expressed genes were identified in liver and muscle respectively. Sex-specific differentially expressed (DE) genes were identified in both sexes. Using network based analysis, different clusters of co-expressed genes that were highly correlated to the diet were detected in males vs. females, in agreement with DE analysis. A total of five regulatory genes in liver tissue associated to EO diet were identified: DNAJB9, MANF, UFM1, CTNNLA1 and NFX1. Our study reveals a sex-dependent effect of EO diet in both tissues, and an influence on the expression of genes mainly involved in immune, inflammatory and stress pathway. Conclusion: Our analysis suggests a sex-dependent effect of the EO dietary supplementation on the expression profile of both liver and muscle tissues. We hypothesize that the presence of EOs could have beneficial effects on wellness of male lamb and further analyses are needed to understand the biological mechanisms behind the different effect of EO metabolites based on sex. Using lamb as a model for nutrigenomics studies, it could be interesting to investigate the effects of EO diets in other species and in humans
The lively accretion disc in NGC 2992. III. Tentative evidence of rapid Ultra Fast Outflow variability
We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert
galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The
time-averaged spectra of the two XMM-Newton orbits show Ultra Fast Outflows
(UFOs) absorbing structures above 9 keV with significance. A
detailed investigation of the temporal evolution on a 5 ks time scale
reveals UFO absorption lines at a confidence level 95% (2) in 8 out
of 50 XMM-Newton segments, estimated via Monte Carlo simulations. We observe a
wind variability corresponding to a length scale of 5 Schwarzschild radii
. Adopting the novel Wind in the Ionised Nuclear Environment (WINE) model,
we estimate the outflowing gas velocity (), column density
() and ionisation state ($\log(\xi_0/erg\ cm\
s^{-1})=3.7-4.7\dot{M}_{out}\simeq0.3-0.8 M_{\odot} yr^{-1}\dot{p}_{out}\simeq 20-90 L_{Bol}/c\dot{E}_K \simeq 2-25 L_{Bol}\approx\approx\approx 5 r_S, 10^{11} {cm}^{-3}$, respectively.Comment: Accepted for publication in the Astrophysical Journal. 21 pages, 11
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