Search Publications
Morphologies of AGN host galaxies using HST/ACS in the CDFS-GOODS field
Hasan, Priya
Using HST/ACS images in four bands F435W, F606W, F775W and F850LP, we identify optical counterparts to the X-ray sources in the Chandra Deep Field South in the GOODS South field. A detailed study has been made of these sources to study their morphological types. We use methods like decomposition of galaxy luminosity profiles, color maps and visual…
Long term spectral variability in the soft gamma-ray repeater SGR 1900+14
Mereghetti, Sandro; Esposito, Paolo; Turolla, Roberto +8 more
We present a systematic analysis of all the BeppoSAX data of SGR1900+14. The observations spanning five years show that the source was brighter than usual on two occasions: ∼20 days after the August 1998 giant flare and during the 105 s long X-ray afterglow following the April 2001 intermediate flare. In the latter case, we explore the …
Thin magnetic hydrogen atmospheres and the neutron star RX J1856.5–3754
Ho, Wynn C. G.; Kaplan, David L.; Chang, Philip +2 more
RX J1856.5–3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire sp…
Hard X-ray emission from the SNR G337.2+0.1
Albacete Colombo, Juan F.; Benaglia, Paula; Combi, Jorge A. +1 more
We report hard X-ray emission of the non-thermal supernova remnant G337.2+0.1. The source presents centrally filled and diffuse X-ray emission. A spectral study confirms that the column density of the central part of the object is about NH∼5.9(±1.5)×1022 cm‑2 and its X-ray spectrum is well represented by a single p…
Filamentary structures in planetary nebulae
Gahm, Gösta F.; Carlqvist, Per; Dahlgren, Hanna
We have studied small-scale, filamentary features in 14 planetary nebulae and found that some structures are recurrent and shaped like the letters V and Y, with the apex or stem pointing toward the central parts of the nebula. Two such filaments containing dust, one in NGC 3132 and one in NGC 7293, were investigated in more detail. The mass and de…
The puzzling X-ray source in RCW103
Caraveo, P. A.; Bignami, G. F.; Tiengo, A. +2 more
1E 161348-5055 (1E) is a compact object lying at the center of the 2000 year old Supernova Remnant (SNR) RCW103. Its original identification as an isolated, radio-quiet neutron star has been questioned in recent years by the observation of a significant long-term variability, as well as by reports of a possible periodicity at ∼6 hours. Here we rep…
Multiwavelength observations of the two unidentified EGRET sources 3EG J0616-3310 and 3EG J1249-8330
Bignami, G. F.; Schirmer, M.; Hatziminaoglou, E. +3 more
We report on the X-ray and optical observation of the two unidentified EGRET sources 3EG J0616-3310 and 3EG J1249-8330. The X-ray coverage performed by the ESA space telescope XMM–Newton provided ∼150 X-ray sources within each of the two γ-ray error-circles. The optical follow-up carried on with the Wide Field Imager at the ESO/MPG 2.2 m telescope…
Using XMM-Newton to measure the spectrum of the Vela pulsar and its phase variation
De Luca, Andrea; Caraveo, Patrizia A.; Manzali, Armando
We report on our analysis of two XMM-Newton observations of the Vela pulsar performed in December 2000 (total exposure time: 96.5 ks). We succeeded in resolving the pulsar spectrum from the surrounding bright nebular emission taking advantage both of the accurate calibration of the EPIC point spread function and of the Chandra/HRC surface brightne…
Intrinsic spectra of the AXPs: De-extinction from model-independent measurement of interstellar column densities
Durant, Martin
Using direct measurements of photo-electric absorption edges, I derive the intrinsic spectra for the Anomalous X-ray Pulsars. In the past, the hydrogen column density, NH had been found by fitting the X-ray spectra with a variety of simple continuum models. Since different models fit equally well, with different values of NH,…
INTEGRAL/XMM views on the MeV source GRO J1411-64
Torres, Diego F.; Zhang, Shu; Barcons, Xavier +9 more
The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically significant sources (likelihood >10) were extracted and analy…