Search Publications
The XMM-Newton spectra of the 2012 outburst of the black hole candidate 4U 1630-47 revisited
Méndez, Mariano; Wang, Yanan
Recent XMM-Newton observations of the black hole candidate 4U 1630-47 during the 2012 outburst revealed three relativistically Doppler-shifted emission lines that were interpreted as arising from baryonic matter in the jet of this source. Here, we reanalyse those data and find an alternative model that, with less free parameters than the model wit…
Extensive X-ray variability studies of NGC 7314 using long XMM-Newton observations
Papadakis, I. E.; Vaughan, S.; Emmanoulopoulos, D. +1 more
We present a detailed X-ray variability study of the low-mass active galactic nuclei (AGN) NGC 7314 using the two newly obtained XMM-Newton observations (140 and 130 ks), together with two archival data sets of shorter duration (45 and 84 ks). The relationship between the X-ray variability characteristics and other physical source properties (such…
Envelope overshooting in low-metallicity intermediate- and high-mass stars: a test with the Sagittarius dwarf irregular galaxy
Slemer, Alessandra; Marigo, Paola; Bianchi, Luciana +5 more
We check the performance of the Padova TRieste Stellar Evolution Code (PARSEC) tracks in reproducing the blue loops of intermediate age and young stellar populations at very low metallicity. We compute new evolutionary PARSEC tracks of intermediate- and high-mass stars from 2 to 350 M⊙ with enhanced envelope overshooting (EO), EO = 2H
Temporal features of LS I +61°303 in hard X-rays from the Swift/BAT survey data
Cusumano, G.; La Parola, V.; Segreto, A. +2 more
We study the long-term spectral and timing behaviour of LS I +61°303 in hard X-rays (15-150 keV) using ∼10 years of survey data from the Swift Burst Alert Telescope (BAT) monitor. We focus on the detection of long periodicities known to be present in this source in multiple wavelengths. We clearly detect three periods: the shorter one at 26.48 d i…
Globular cluster scale sizes in giant galaxies: orbital anisotropy and tidally underfilling clusters in M87, NGC 1399 and NGC 5128
Sills, Alison; Puzia, Thomas H.; Paolillo, Maurizio +4 more
We investigate the shallow increase in globular cluster half-light radii with projected galactocentric distance Rgc observed in the giant galaxies M87, NGC 1399, and NGC 5128. To model the trend in each galaxy, we explore the effects of orbital anisotropy and tidally underfilling clusters. While a strong degeneracy exists between the tw…
The XMM Cluster Survey: the halo occupation number of BOSS galaxies in X-ray clusters
Streblyanska, Alina; Schneider, Donald P.; Hilton, Matt +26 more
We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 < z < 0.4) and Constant-Mass (CMASS: 0.43 < z < 0.7) galaxies is inferred via …
The ionized X-ray outflowing torus in ESO 323-G77: low-ionization clumps confined by homogeneous warm absorbers
Miniutti, G.; Krongold, Y.; Longinotti, A. L. +2 more
We report on the long- and short-term X-ray spectral analysis of the polar-scattered Seyfert 1.2 galaxy ESO 323-G77, observed in three epochs between 2006 and 2013 with Chandra and XMM-Newton. Four high-resolution Chandra observations give us a unique opportunity to study the properties of the absorbers in detail, as well as their short time-scale…
A possible mechanism for the formation of magnetic field dropouts in the coma of 67P/Churyumov-Gerasimenko
Altwegg, K.; Huang, Z.; Jia, X. +10 more
The Rosetta Plasma Consortium MAGnetometer (RPC-MAG) has detected signatures of diamagnetic regions associated with comet 67P/Churyumov-Gerasimenko at distances from 30 to 400 km at different heliocentric distances, which is larger than what has been predicted by numerical simulations of the cometary plasam environment. The physical mechanism behi…
The featureless and non-variable optical spectral energy distribution of AXP 4U 0142+61
Muñoz-Darias, T.; Casares, J.; de Ugarte Postigo, A.
We present GTC-10.4 m spectroscopy and multiband photometry of the faint (r ∼ 26) optical counterpart of the anomalous X-ray pulsar 4U 0142+61. The 5000-9000 Å spectrum - the first obtained for a magnetar - is featureless, allowing us to set an equivalent width upper limit EW < 25 Å to the presence of emission lines in the H α region. Multiband…
Ultraviolet emission lines of Si II in cool star and solar spectra
Ayres, Thomas R.; Laha, Sibasish; Ferland, Gary J. +6 more
Recent atomic physics calculations for Si II are employed within the CLOUDY modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, β Geminorum, α Centauri A and B, as well as previously published HST/GHRS observations of α Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrogra…