Temperature Measurement during Thermonuclear X-ray Bursts with BeppoSAX

We have carried out a study of temperature evolution during thermonuclear bursts in LMXBs using broad band data from two instruments onboard BeppoSAX, the MECS and the PDS. However, instead of applying the standard technique of time resolved spectroscopy, we have determined the temperature in small time intervals using the ratio of count rates in the two instruments assuming a blackbody nature of burst emission and different interstellar absorption for different sources. Data from a total of twelve observations of six sources were analysed during which 22 bursts were detected. We have obtained temperatures as high as ~3.0 keV, even when there is no evidence of photospheric radius expansion. These high temperatures were observed in the sources within different broadband spectral states (soft and hard).Comment: To appear in New Astronom

The AstroSat observation of accreting millisecond X-ray pulsar SAX J1808.4-3658 during its 2019 outburst

We report on the analysis of the AstroSat dataset of the accreting millisecond X-ray pulsar SAX J1808.4-3658, obtained during its 2019 outburst. We found coherent pulsations at $\sim 401$ Hz and an orbital solution consistent with previous studies. The 3-20 keV pulse profile can be well fitted with three harmonically related sinusoidal components with background-corrected fractional amplitude of $\sim 3.5 \%$, $\sim 1.2 \%$ and $\sim 0.37 \%$ for fundamental, second and third harmonic, respectively. Our energy-resolved pulse profile evolution study indicate a strong energy dependence. We also observed a soft lag in fundamental and hard lag during its harmonic. The broadband spectrum of SAX J1808.4-3658 can be well described with a combination of thermal emission component with $kT \sim 1$ keV, a thermal Comptonization ($\Gamma \sim 1.67$) from the hot corona and broad emission lines due to Fe.Comment: Accepted for publication in MNRA

Características de las pacientes con cáncer de ovario en el Hospital de San José, Bogotá D.C., 2009-2013

ResumenEl cáncer de ovario presenta alta prevalencia con 238.719 casos reportados a nivel mundial, cuya mortalidad alcanza y supera el 50%, siendo la mayor causada por cáncer ginecológico.ObjetivoDescribir las características de las pacientes diagnosticadas o tratadas por cáncer de ovario en el Servicio de Ginecología Oncológica del Hospital de San José en el periodo 2009-2013.Materiales y métodosSerie de casos retrospectiva.ResultadosSe incluyeron 68 pacientes con edad promedio de 49 años (DE: 15,5, mínima: 14 y máxima: 82); 57,5% (n=39) fueron posmenopáusicas. El tipo histológico seroso papilar fue el más común en pre y menopáusicas. El 70,6% se diagnosticaron en estadios iii-iv. Se logró citorreducción óptima (R1) o total (R0) en el 40,9%. Se administró quimioterapia adyuvante al 74,24%. La supervivencia libre de recurrencia fue de 63,23% y la supervivencia global de 54,41%.ConclusiónEn nuestra población el cáncer de ovario se diagnosticó en edades más tempranas que lo reportado a nivel mundial. Coincidiendo con la literatura la histología más frecuente fue el seroso papilar, que se detectó en etapas avanzadas y con alta mortalidad.AbstractOvarian cancer has high prevalence, with 238,719 cases reported worldwide. The death rate is greater than 50%, and accounts for the most cancer deaths from gynaecological tumours.ObjectiveTo describe the features of patients diagnosed or treated for ovarian cancer at the Oncological Gynaecology Department of the Hospital de San José during the period 2009-2013.Materials and methodsA retrospective case series.ResultsA total of 68 patients were included, with a mean age of 49 years (SD 15.5: range: 14 - 82), of whom 39 (57.5%) were post-menopausal. Serous papillary tumours were the most common histology in pre- and menopausal patients, with 70.6% being diagnosed in stages III-IV. Optimal cytoreduction (R1) or total cytoreduction (R0) was achieved in 40.9%. Adjuvant chemotherapy was administered to 74.24%. Tumour-free survival rate was 63.23%, and overall survival rate was 54.41%.ConclusionIn our population, ovarian cancer is diagnosed at a more early age than that reported in the world literature. Coinciding with the literature, the serous papillary histotype in advanced stages is the most frequently detected type with a high mortality rate

A broadband look of the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 using AstroSat and XMM-Newton

SAX J1748.9-2021 is a transient accretion powered millisecond X-ray pulsar located in the Globular cluster NGC 6440. We report on the spectral and timing analysis of SAX J1748.9-2021 performed on AstroSat data taken during its faint and short outburst of 2017. We derived the best-fitting orbital solution for the 2017 outburst and obtained an average local spin frequency of 442.361098(3) Hz. The pulse profile obtained from 3-7 keV and 7-20 keV energy bands suggest constant fractional amplitude ~0.5% for fundamental component, contrary to previously observed energy pulse profile dependence. Our AstroSat observations revealed the source to be in a hard spectral state. The 1-50 keV spectrum from SXT and LAXPC on-board AstroSat can be well described with a single temperature blackbody and thermal Comptonization. Moreover, we found that the combined spectra from XMM-Newton (EPIC-PN) and AstroSat (SXT+LAXPC) indicated the presence of reflection features in the form of iron (Fe K${\alpha}$) line that we modeled with the reflection model xillvercp. One of the two X-ray burst observed during the AstroSat/LAXPC observation showed hard X-ray emission (>30 keV) due to Compton up-scattering of thermal photons by the hot corona. Time resolved analysis performed on the bursts revealed complex evolution in emission radius of blackbody for second burst suggestive of mild photospheric radius expansion.Comment: 9 pages, 8 figures. Accepted for publication in MNRA

Evolution of timing and spectral characteristics of 4U 1901+03 during its 2019 outburst using the Swift and NuSTAR observatories

We report the results from a detailed timing and spectral study of transient X-ray pulsars, 4U 1901+03 during its 2019 outburst. We performed broadband spectroscopy in the 1-70 keV energy band using four observations made with Swift and NuSTAR at different intensity levels. Our timing results reveal the presence of highly variable pulse profiles dependent on both luminosity and energy. Our spectroscopy results showed the presence of a cyclotron resonance scattering feature (CRSF) at ~30 keV. This feature at 30 keV is highly luminosity and pulse-phase dependent. Phase-averaged spectra during the last two observations, made close to the declining phase of the outburst showed the presence of this feature at around 30 keV. The existence of CRSF at 30 keV during these observations is well supported by an abrupt change in the shape of pulse profiles found close to this energy. We also found that 30 keV feature was significantly detected in the pulse-phase resolved spectra of observations made at relatively high luminosities. Moreover, all spectral fit parameters showed a strong pulse phase dependence. In line with the previous findings, an absorption feature at around 10 keV is significantly observed in the phase-averaged X-ray spectra of all observations and also showed a strong pulse phase dependence.Comment: 18 pages, accepted for publication in MNRA

Phase-resolved spectral analysis of the 11 mHz quasi-periodic oscillation in the black hole candidate H1743-322

H1743-322 is one of the few black hole candidates (BHCs) in low-mass X-ray binaries that shows mHz quasi-periodic oscillations (QPOs) that are not associated with the more common type A, B, and C oscillations seen in the X-ray light curves of typical BHC systems. To better understand the physical origin of the mHz oscillations, we carried out a phase-resolved spectroscopic study of two RXTE observations of this source. As previously reported, the averaged energy spectra of H1743-322 show a strong iron line at 6.5 keV. Here we found evidence that the line flux appears to be modulated at twice the frequency of the mHz QPO. This line flux modulation is very similar to the one previously found for the type-C QPO in this source. We interpret the possibly periodic line flux modulation with this mHz QPO in terms of Lense-Thirring precession of the inner flow, and discuss the possible connection with the modulation of the line properties with the type-C QPO frequency

Erratum: The reflection component in the average and heartbeat spectra of the black-hole candidate IGR J17091-3624 during the 2016 outburst

In the paper 'The reflection component in the average and heartbeat spectra of the black-hole candidate IGR J17091-3642 during the 2016 outburst', MNRAS, 478, 4837, sty1372 (2018), we mistakenly used the name of the black-hole candidate as IGR J17091-3642 instead of the correct one, IGR J17091-3624.</p

The reflection component in the average and heartbeat spectra of the black hole candidate IGR J17091-3642 during the 2016 outburst

We present simultaneous NuSTAR and Swift observations of the black hole transient IGR J17091-3642 during its 2016 outburst. By jointly fitting six NuSTAR and four Swift spectra, we found that during this outburst the source evolves from the hard to the hard/soft intermediate and back to the hard state, similar to the 2011 outburst. Unlike in the previous outburst, in this case we observed both a broad emission and an moderately broad absorption line in our observations. Our fits favour an accretion disc with an inclination angle of $\sim$$45\deg$ with respect to the line of sight and a high iron abundance of $3.5\pm0.3$ in units of the solar abundance. We also observed heartbeat variability in one NuSTAR observation. We fitted the phase-resolved spectra of this observation and found that the reflected emission varies independently from the direct emission, whereas in the fits to the average spectra these two quantities are strongly correlated. Assuming that in IGR J17091-3642 the inner radius of the disc both in the average and the phase-resolved spectra is located at the radius of the innermost stable circular orbit, with 90% confidence the spin parameter of the black hole in this system is $-0.13\leq a_{*}\leq0.27$.Comment: 14 pages, 12 figure