1,543 research outputs found
Discovery of a Cyclotron Resonance Scattering Feature in the X-ray Spectrum of XTE J1946+274
Observations of the transient accreting pulsar XTE J1946+274 made with the
Rossi X-ray Timing Explorer during the course of the 1998 September-November
outburst, reveal a cyclotron resonance scattering feature (or "cyclotron line")
in the hard X-ray spectrum near 35 keV. We determine a centroid energy of 36.2
+0.5/-0.7 keV, which implies a magnetic field strength of 3.1(1+z)x10^12 G,
where z is the gravitational redshift of the scattering region. The optical
depth, Tau = 0.33 +0.07/-0.06, and width, sigma = 3.37 +0.92/-0.75 keV, are
typical of known cyclotron lines in other pulsars. This discovery makes XTE
J1946+274 one of thirteen pulsars with securely detected cyclotron lines
resulting in direct magnetic field measurements.Comment: Five pages including four postscript figures and two tables. Uses
emulateapj5. Published in ApJ Letters:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001ApJ...563L..35
The pre-outburst flare of the A 0535+26 August/September 2005 outburst
We study the spectral and temporal behavior of the High Mass X-ray Binary A
0535+26 during a `pre-outburst flare' which took place ~5 d before the peak of
a normal (type I) outburst in August/September 2005. We compare the studied
behavior with that observed during the outburst. We analyse RXTE observations
that monitored A 0535+26 during the outburst. We complete spectral and timing
analyses of the data. We study the evolution of the pulse period, present
energy-dependent pulse profiles both at the initial pre-outburst flare and
close to outburst maximum, and measure how the cyclotron resonance-scattering
feature (hereafter CRSF) evolves. We present three main results: a constant
period P=103.3960(5)s is measured until periastron passage, followed by a
spin-up with a decreasing period derivative of Pdot=(-1.69+/-0.04)x10^(-8)s/s
at MJD 53618, and P remains constant again at the end of the main outburst. The
spin-up provides evidence for the existence of an accretion disk during the
normal outburst. We measure a CRSF energy of Ecyc~50kev during the pre-outburst
flare, and Ecyc~46kev during the main outburst. The pulse shape, which varies
significantly during both pre-outburst flare and main outburst, evolves
strongly with photon energy.Comment: 4 pages, 4 figures, accepted for publication in A&A Letters. To be
published in parallel to Postnov et al. 200
INTEGRAL observations of V0332+53 in outburst
We present the analysis of a 100ksec Integral(3-100kev) observation of the
transient X-ray pulsar V0332+53 inoutburst. The source is pulsating at
P=4.3751+/-0.0002s with a clear double pulse from 6 kev to 60 kev. The average
flux was ~550mCrab between 20 kev and 60 kev. We modeled the broad band
continuum from 5 kev to 100 kev with a power-law modified by an exponential cut
off. We observe three cyclotron lines: the fundamental line at 24.9+/-0.1 kev,
the first harmonic at 50.5+/-0.1 kev as well as the second harmonic
at71.7+/-0.8 kev, thus confirming the discovery of the harmonic lines by Coburn
et al. (2005) in RXTE data.Comment: 4 pages, 3 figures. Accepted for publication in A&A Letter
Monitoring PSR B1509–58 with RXTE: Spectral analysis 1996–2010
We present an analysis of the X-ray spectra of the young, Crab-like pulsar PSR B1509–58 (pulse period P ~ 151ms) observed by RXTE over 14 years since the beginning of the mission in 1996. The uniform dataset is especially well suited for studying the stability of the spectral parameters over time as well as for determining pulse phase resolved spectral parameters with high significance. The phase averaged spectra as well as the resolved spectra can be well described by an absorbed power law
Dynamic Scaling of an Adsorption-Diffusion Process on Fractals
A dynamic scaling of a diffusion process involving the Langmuir type
adsorption is studied. We find dynamic scaling functions in one and two
dimensions and compare them with direct numerical simulations, and we further
study the dynamic scaling law on fractal surfaces. The adsorption-diffusion
process obeys the fracton dynamics on the fractal surfaces.Comment: 9 pages, 7 figure
How to read a next-generation sequencing report-what oncologists need to know.
Next-generation sequencing (NGS) of tumor cell-derived DNA/RNA to screen for targetable genomic alterations is now widely available and has become part of routine practice in oncology. NGS testing strategies depend on cancer type, disease stage and the impact of results on treatment selection. The European Society for Medical Oncology (ESMO) has recently published recommendations for the use of NGS in patients with advanced cancer. We complement the ESMO recommendations with a practical review of how oncologists should read and interpret NGS reports. A concise and straightforward NGS report contains details of the tumor sample, the technology used and highlights not only the most important and potentially actionable results, but also other pathogenic alterations detected. Variants of unknown significance should also be listed. Interpretation of NGS reports should be a joint effort between molecular pathologists, tumor biologists and clinicians. Rather than relying and acting on the information provided by the NGS report, oncologists need to obtain a basic level of understanding to read and interpret NGS results. Comprehensive annotated databases are available for clinicians to review the information detailed in the NGS report. Molecular tumor boards do not only stimulate debate and exchange, but may also help to interpret challenging reports and to ensure continuing medical education
4U 1909+07: a Hidden Pearl
We present a detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U1909+07 is a persistent accreting X-ray pulsar with a period of approximately 605 s. The period changes erratically consistent with a random walk expected for a wind accreting system. INTEGRAL detects the source with an average of 2.4 cps (corresponding to 15mCrab), but sometimes exhibits flaring activity up to 50 cps (i.e. 300mCrab). The strongly energy dependent pulse profile shows a double peaked structure at low energies and only a single narrow peak at energies above 20 keV. The phase averaged spectrum is well described by a powerlaw modified at higher energies by an exponential cutoff and photoelectric absorption at low energies. In addition at 6.4 keV a strong iron fluorescence line and at lower energies a blackbody component are present. We performed phase resolved spectroscopy to study the pulse phase dependence of the spectral parameters: while most spectral parameters are constant within uncertainties, the blackbody normalization and the cutoff folding energy vary strongly with phase
Discovery of a Third Harmonic Cyclotron Resonance Scattering Feature in the X-ray Spectrum of 4U 0115+63
We have discovered a third harmonic cyclotron resonance scattering feature
(CRSF) in observations of the recent outburst of 4U 0115+63 with the Rossi
X-ray Timing Explorer (RXTE). The spectrum in a narrow pulse phase range shows
CRSFs at 12.40+0.65/-0.35, 21.45+0.25/-0.38, and 33.56+0.70/-0.90 keV. With
centroid energy ratios to the fundamental of 1.73+/-0.08 and 2.71+/-0.13, the
CRSFs are not harmonically spaced. Strong variability of the continuum and
CRSFs with pulse phase indicate a complex emission geometry near the neutron
star polar cap. In addition, one RXTE observation, which spanned periastron
passage, revealed a strong 2 mHz quasi-periodic oscillation (QPO). This is
slower by two orders of magnitude than the beat-frequency QPO expected in this
system and slower by a factor of more than 5 compared with other QPOs seen in
accreting X-ray pulsars.Comment: To appear in The Astrophysical Journal Letters. 4 pages, 5 figures.
Uses "emulateapj.sty". Revised version includes new figures and additions to
the analysi
A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL
In this Letter we present results from INTEGRAL and RXTE observations of the
spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its
August/September 2005 normal (type I) outburst with an average flux
F(5-100keV)~400mCrab. The search for cyclotron resonance scattering features
(fundamental and harmonic) is one major focus of the paper. Our analysis is
based on data from INTEGRAL and RXTE Target of Opportunity Observations
performed during the outburst. The pulse period is determined. X-ray pulse
profiles in different energy ranges are analyzed. The broad band INTEGRAL and
RXTE pulse phase averaged X-ray spectra are studied. The evolution of the
fundamental cyclotron line at different luminosities is analyzed. The pulse
period P is measured to be 103.39315(5)s at MJD 53614.5137. Two absorption
features are detected in the phase averaged spectra at E_1~45keV and
E_2~100keV. These can be interpreted as the fundamental cyclotron resonance
scattering feature and its first harmonic and therefore the magnetic field can
be estimated to be B~4x10^12G.Comment: 4 pages, 5 figures, accepted for publication in A&A Letter
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