Black Hole Mass of the Ultraluminous X-ray source M82 X-1

We report the first clear evidence for the simultaneous presence of a low frequency break and a QPO in the fluctuation power spectrum of a well known ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The break occurs at a frequency of 34.2_{-3}^{+6}mHz. The QPO has a centroid at 114.3\pm1.5mHz, a coherence Q~3.5 and an amplitude (rms) of 19% in the 2-10keV band. The power spectrum is approximately flat below the break frequency and then falls off above the break frequency as a power law with the QPO superimposed. This form of the power spectrum is characteristic of the Galactic X-ray binaries (XRBs) in their high or intermediate states. M82 X-1 was likely in an intermediate state during the observation. The EPIC PN spectrum is well described by a model comprising an absorbed power-law (Gamma~2) and an iron line at ~6.6keV with a width sigma~0.2keV and an equivalent width of ~180eV. Using the well established correlations between the power and energy spectral parameters for XRBs, we estimate a black hole mass for M82 X-1 in the range of 25-520Msun including systematic errors that arise due to the uncertainty in the calibration of the photon spectral index versus QPO frequency relation.Comment: Final version, accepted for publication in ApJ Letter

On the origin of the featureless soft X-ray excess emission from the Seyfert 1 galaxy ESO~198--G24

We present medium and high resolution X-ray spectral study of a Seyfert 1 galaxy ESO~198--G24 using a long (122 ks) XMM-Newton observation performed in February 2006. The source has a prominent featureless soft X-ray excess below 2\kev. This makes the source well suited to investigate the origin of the soft excess. Two physical models -- blurred reflection, and optically thick thermal Comptonization in a warm plasma, describe the soft-excess equally well resulting in similar fits in the 0.3-10\kev band. These models also yield similar fits to the broad-band UV (Optical Monitor) and X-ray data. XMM-Newton observations performed in 2000, 2001 and 2006 on this source show flux variability. From 2001 to 2006, the UV flux increased by $\sim23\%$ while the 2-10\kev X-ray flux as well as the soft-excess flux decreased by ~ 20. This observation can be described in the blurred reflection scenario by a truncated accretion disk whose inner-most radius had come closer to the blackhole. We find that the best-fit inner radius of the accretion disk decreases from R_{in}=4.93_{-1.10}^{+1.12}R_G to R_{in}<2.5R_G from 2001 to 2006. This leads to an increase in the UV flux and compressing the corona, leading to reduction of the powerlaw flux and therefore the soft-excess. The blurred reflection model seems to better describe the soft-excess for this source.Comment: Accepted for publication in the 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