Search Publications
The complications of learning from Super Soft Source X-ray spectra
Ness, Jan-Uwe
Super Soft X-ray Sources (SSS) are powered by nuclear burning on the surface of an accreting white dwarf, they are seen around 0.1-1 keV (thus in the soft X-ray regime), depending on effective temperature and the amount of intervening interstellar neutral hydrogen (NH). The most realistic model to derive physical parameters from observe…
X-ray properties of dwarf nova EY Cyg and the companion star using an XMM-Newton observation
Balman, Şölen; Nabizadeh, Armin
We present the X-ray analysis of dwarf nova EY Cyg using the 45 ks XMM-Newton observatory archival data obtained in quiescence. We find orbital modulations in X-rays. We simultaneously fitted EPIC pn, MOS1 and MOS2 data using a model for interstellar medium absorption (tbabs) and a multi-temperature plasma emission model with a power-law distribut…
Data-driven modelling of the Van Allen Belts: The 5DRBM model for trapped electrons
Kretschmar, Peter; Ness, Jan-Uwe; Kuulkers, Erik +10 more
The magnetosphere sustained by the rotation of the Earth's liquid iron core traps charged particles, mostly electrons and protons, into structures referred to as the Van Allen Belts. These radiation belts, in which the density of charged energetic particles can be very destructive for sensitive instrumentation, have to be crossed on every orbit of…
X-rays from magnetic intermediate mass Ap/Bp stars
Robrade, Jan
The X-ray emission of magnetic intermediate mass Ap/Bp stars is reviewed and put into context of intrinsic as well as extrinsic hypotheses for its origin. New X-ray observations of Ap/Bp stars are presented and combined with an updated analysis of the available datasets, providing the largest sample of its type that is currently available. In the …
A study of the main resonances outside the geostationary ring
Celletti, Alessandra; Galeş, Cătălin
We investigate the dynamics of satellites and space debris in external resonances, namely in the region outside the geostationary ring. Precisely, we focus on the 1:2, 1:3, 2:3 resonances, which are located at about 66 931.4 km, 87 705.0 km, 55 250.7 km, respectively. Some of these resonances have been already exploited in space missions, like XMM…
Discovery of new X-ray sources near the unidentified gamma-ray source HESS J1841-055
Koyama, K.; Nobukawa, M.; Tsuru, T. G. +1 more
HESS J1841-055 is a diffuse unidentified gamma-ray source with the size of ∼1°.3 × 1°. No conclusive counterpart in other wavelengths has so far detected. To search for X-rays responsible for the TeV emission, the Suzaku observations were conducted, which covered a half region of the HESS source. In the soft band (0.5-2.0 keV), we discovered a dif…
The optical emission lines of type 1 X-ray bright Active Galactic Nuclei
La Mura, G.; Ciroi, S.; Cracco, V. +3 more
A strong X-ray emission is one of the defining signatures of nuclear activity in galaxies. According to the Unified Model for Active Galactic Nuclei (AGN), both the X-ray radiation and the prominent broad emission lines, characterizing the optical and UV spectra of Type 1 AGNs, are originated in the innermost regions of the sources, close to the S…
Are Boltzmann plots of hydrogen Balmer lines a tool for identifying a subclass of S1 AGN?
Popović, L. Č.; La Mura, G.; Ciroi, S. +4 more
It is becoming clear that we can define two different types of nearby AGN belonging to the Seyfert 1 class (S1), on the basis of the match of the intensities of their Broad Balmer Lines (BBL) with the Boltzmann Plots (BP). These two types of S1 galaxies, that we call BP-S1 and NoBP-S1, are characterized, in first approximation, by Broad Line Regio…
Observations of supergiant fast X-ray transients with LOFT
Esposito, P.; Romano, P.; Ferrigno, C. +2 more
Supergiant fast X-ray transients are a subclass of high mass X-ray binaries displaying a peculiar and still poorly understood extreme variability in the X-ray domain. These sources undergo short sporadic outbursts (L∼ 1036-1037 erg s-1), lasting few ks at the most, and spend a large fraction of their tim…
A view of supernova remnant CTB 37A with the Fermi Gamma-ray Space Telescope
Fermi-LAT Collaboration; Brandt, T. J.
Supernovae and their remnants have long been favored as cosmic ray accelerators. Recent data from the Fermi Gamma-ray Space Telescope has given us an improved window into such sources, including the remnant CTB 37A. Using the Fermi Large Area Telescope, we found significant gamma-ray emission coincident with the remnant, which also emits in radio,…