299 research outputs found
New VLT observations of the Fermi pulsar PSR J1048-5832
PSR J1048-5832 is a Vela-like (P=123.6 ms; tau~20.3 kyr) gamma-ray pulsar
detected by Fermi, at a distance of ~2.7 kpc and with a rotational energy loss
rate dot{E}_{SD} ~2 x 10^{36} erg/s. The PSR J1048-5832 field has been observed
with the VLT in the V and R bands. We used these data to determine the colour
of the object detected closest to the Chandra position (Star D) and confirm
that it is not associated with the pulsar. For the estimated extinction along
the line of sight, inferred from a re-analysis of the Chandra and XMM-Newton
spectra, the fluxes of Star D (V~26.7; R~25.8) imply a -0.13 < (V-R)_0 < 0.6.
This means that the PSR J1048-5832 spectrum would be unusually red compared to
the Vela pulsar.Moreover, the ratio between the unabsorbed optical and X-ray
flux of PSR J1048-5832 would be much higher than for other young pulsars. Thus,
we conclude that Star D is not the PSR J1048-5832 counterpart. We compared the
derived R and V-band upper limits (R>26.4; V>27.6) with the extrapolation of
the X and gamma-ray spectra and constrained the pulsar spectrum at
low-energies. In particular, the VLT upper limits suggest that the pulsar
spectrum could be consistent with a single power-law, stretching from the
gamma-rays to the optical.Comment: 5 pages, 2 figures, accepted for publication on Monthly Notices of
the Royal Astronomical Society Main Journa
The impact of the GDPR on the governance of biobank research
Governance of health and genomic data access in the context of biobanking is of salient importance in implementing the EU General Data Protection Regulation (GDPR). Various components of data access governance could be considered as ‘organizational measures’ which are stressed in the Article 89(1) GDPR together with technical measures that should be used in order to safeguard rights of the data subjects when processing data under research exemption rules. In this chapter, we address the core elements regarding governance of biobanks in the view of GDPR, including conditions for processing personal data, data access models, oversight bodies and data access agreements. We conclude by highlighting the importance of guidelines and policy documents in helping the biobanks in improving the data access governance. In addition, we stress that it is important to ensure the existing and emerging oversight bodies are equipped with adequate expertise regarding using and sharing health and genomic data and are aware of the associated informational risks
Supergiant Fast X-ray Transients uncovered by the EXTraS project: flares reveal the development of magnetospheric instability in accreting neutron stars
The low luminosity, X-ray flaring activity, of the sub-class of high mass
X-ray binaries called Supergiant Fast X-ray Transients, has been investigated
using XMM-Newton public observations, taking advantage of the products made
publicly available by the EXTraS project. One of the goals of EXTraS was to
extract from the XMM-Newton public archive information on the aperiodic
variability of all sources observed in the soft X-ray range with EPIC (0.2-12
keV). Adopting a Bayesian block decomposition of the X-ray light curves of a
sample of SFXTs, we picked out 144 X-ray flares, covering a large range of soft
X-ray luminosities (1e32-1e36 erg/s). We measured temporal quantities, like the
rise time to and the decay time from the peak of the flares, their duration and
the time interval between adjacent flares. We also estimated the peak
luminosity, average accretion rate and energy release in the flares. The
observed soft X-ray properties of low-luminosity flaring activity from SFXTs is
in qualitative agreement with what is expected by the application of the
Rayleigh-Taylor instability model in accreting plasma near the neutron star
magnetosphere. In the case of rapidly rotating neutron stars, sporadic
accretion from temporary discs cannot be excluded.Comment: Accepted for publication in MNRAS (accepted 2019 May 1; received 2019
April 30; in original form 2019 February 25). 22 pages, 16 figures, 3 tables
The first orbital period of a very bright and fast Nova in M31: M31N 2013-01b
We present the first X-ray and UV/optical observations of a very bright and
fast nova in the disc of M31, M31N 2013-01b. The nova reached a peak magnitude
15 mag and decayed by 2 magnitudes in only 3 days, making it one of the
brightest and fastest novae ever detected in Andromeda. From archival
multi-band data we have been able to trace its fast evolution down to
mag in less than two weeks and to uncover for the first time the Super-Soft
X-ray phase, whose onset occurred 10-30 days from the optical maximum. The
X-ray spectrum is consistent with a blackbody with a temperature of 50 eV
and emitting radius of 4 cm, larger than a white dwarf
radius, indicating an expanded region. Its peak X-ray luminosity, 3.5 erg s, locates M31N 2013-01b among the most luminous novae in
M31. We also unambiguously detect a short 1.280.02 h X-ray periodicity
that we ascribe to the binary orbital period, possibly due to partial eclipses.
This makes M31N 2013-01b the first nova in M31 with an orbital period
determined. The short period also makes this nova one of the few known below
the 2-3 h orbital period gap. All the observed characteristics strongly
indicate that M31N 2013-01b harbours a massive white dwarf and a very low-mass
companion, consistent with being a nova belonging to the disc population of the
Andromeda Galaxy.Comment: 9 pages, 3 figures, 2 tables; accepted by the Astrophysical Journa
A systematic analysis of the XMM-Newton background: III. Impact of the magnetospheric environment
A detailed characterization of the particle induced background is fundamental
for many of the scientific objectives of the Athena X-ray telescope, thus an
adequate knowledge of the background that will be encountered by Athena is
desirable. Current X-ray telescopes have shown that the intensity of the
particle induced background can be highly variable. Different regions of the
magnetosphere can have very different environmental conditions, which can, in
principle, differently affect the particle induced background detected by the
instruments. We present results concerning the influence of the magnetospheric
environment on the background detected by EPIC instrument onboard XMM-Newton
through the estimate of the variation of the in-Field-of-View background excess
along the XMM-Newton orbit. An important contribution to the XMM background,
which may affect the Athena background as well, comes from soft proton flares.
Along with the flaring component a low-intensity component is also present. We
find that both show modest variations in the different magnetozones and that
the soft proton component shows a strong trend with the distance from Earth.Comment: To appear in Experimental Astronomy. Presented at AHEAD Background
Workshop, 28-30 November 2016. Rome, Ital
A Systematic Analysis of the XMM-Newton Background: I. Dataset and Extraction Procedures
XMM-Newton is the direct precursor of the future ESA ATHENA mission. A study
of its particle-induced background provides therefore significant insight for
the ATHENA mission design. We make use of about 12 years of data, products from
the third XMM-Newton catalog as well as FP7 EXTraS project to avoid celestial
sources contamination and to disentangle the different components of the
XMM-Newton particle-induced background. Within the ESA R&D AREMBES
collaboration, we built new analysis pipelines to study the different
components of this background: this covers time behavior as well as spectral
and spatial characteristics.Comment: To appear in Experimental Astronomy, presented at AHEAD Background
Workshop, 28-30 November 2016, Rome, Italy. 12 pages, 6 figure
X-ray pulsations from the radio-quiet gamma-ray pulsar in CTA 1
Prompted by the Fermi LAT discovery of a radio-quiet gamma-ray pulsar inside
the CTA 1 supernova remnant, we obtained a 130 ks XMM-Newton observation to
assess the timing behavior of this pulsar. Exploiting both the unprecedented
photon harvest and the contemporary Fermi LAT timing measurements, a 4.7 sigma
single peak pulsation is detected, making PSR J0007+7303 the second example,
after Geminga, of a radio-quiet gamma-ray pulsar also seen to pulsate in
X-rays. Phase-resolved spectroscopy shows that the off-pulse portion of the
light curve is dominated by a power-law, non-thermal spectrum, while the X-ray
peak emission appears to be mainly of thermal origin, probably from a polar cap
heated by magnetospheric return currents, pointing to a hot spot varying
throughout the pulsar rotation.Comment: 19 pages, 4 figures. Accepted for publication in ApJ Letter
Radio-quiet and radio-loud pulsars: similar in Gamma-rays but different in X-rays
We present new Chandra and XMM-Newton observations of a sample of eight
radio-quiet Gamma-ray pulsars detected by the Fermi Large Area Telescope. For
all eight pulsars we identify the X-ray counterpart, based on the X-ray source
localization and the best position obtained from Gamma-ray pulsar timing. For
PSR J2030+4415 we found evidence for an about 10 arcsec-long pulsar wind
nebula. Our new results consolidate the work from Marelli et al. 2011 and
confirm that, on average, the Gamma-ray--to--X-ray flux ratios (Fgamma/Fx) of
radio-quiet pulsars are higher than for the radio-loud ones. Furthermore, while
the Fgamma/Fx distribution features a single peak for the radio-quiet pulsars,
the distribution is more dispersed for the radio-loud ones, possibly showing
two peaks. We discuss possible implications of these different distributions
based on current models for pulsar X-ray emission.Comment: Accepted for publication in The Astrophysical Journal; 12 pages, 3
figures, 2 table
GLIS3 and Thyroid: A Pleiotropic Candidate Gene for Congenital Hypothyroidism
Variations in the transcription factor Gli-similar 3 (GLIS3) gene have been associated to variable congenital endocrine defects, including both morphogenetic and functional thyroid alterations. Evidence from Glis3 knockout mice indicates a relevant role for GLIS3 in thyroid hormone biosynthesis and postnatal thyroid gland growth, with a mechanism of action downstream of the TSH/TSHR interaction. However, the pathophysiological role of this transcription factor during the embryonic thyroid development remains unexplored. In this manuscript, we will provide an overview of the current knowledge on GLIS3 function during development. As a perspective, we will present preliminary evidence in the zebrafish model in support of a potential role for this pleiotropic transcription factor in the early stages of thyroid gland development
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