Search Publications
Dust-scattered X-ray halos around gamma-ray bursts: GRB 031203 revisited and the new case of GRB 050713A
Tiengo, A.; Mereghetti, S.
Scattering by interstellar dust grains can produce time variable X-ray halos around gamma-ray bursts (GRB). In particular, an X-ray expanding ring is expected when a short pulse of X-ray radiation is scattered by a narrow layer of dust in our Galaxy. We present a new method for detecting and analyzing dust-scattering expanding rings around gamma-r…
A Catalog of Transient X-Ray Sources in M31
Williams, Benjamin F.; Garcia, Michael R.; Naik, S. +1 more
From 1999 October to 2002 August, 45 transient X-ray sources were detected in M31 by Chandra and XMM-Newton. We have performed spectral analysis of all XMM-Newton and Chandra ACIS detections of these sources, as well as flux measurements of Chandra HRC detections. The result is absorption-corrected X-ray light curves for these sources covering thi…
On the horizontal branch of the galactic globular cluster NGC 2808
Zoccali, M.; Bono, G.; Cassisi, S. +3 more
We present new UV (F218W) data for stars in the central region of the Galactic globular cluster NGC 2808, collected with the WFPC2 camera on board the Hubble Space Telescope. These data together with F439W and F555W-band data and previous ground-based observations provide a multifrequency coverage of the cluster stellar population extending up to …
Probing the proper motion of the central compact object in Puppis-A with the Chandra high resolution camera
Hui, C. Y.; Becker, W.
By making use of the sub-arcsecond angular resolution of the High Resolution Camera (HRC-I) aboard the Chandra X-ray satellite we have examined the central compact object RX J0822-4300 in the supernova remnant Puppis-A for a possible proper motion. Using data which span an epoch of 1952 days we found the position of RX J0822-4300 different by 0.57…
Subaru optical observations of the two middle-aged pulsars PSR B0656+14 and Geminga
Kawai, N.; Zharikov, S. V.; Urata, Y. +6 more
Aims.We carried out a deep subarcsecond BRI imaging of the two middle-aged pulsars to establish their properties in the optical range. Methods.Astrometry and photometry methods are applied to identify the pulsars and to measure their fluxes. We also reanalyze archival ESO/NTT and HST broadband data and find that some published fluxes for Geminga w…
Galaxies under the cosmic microscope: resolved spectroscopy and new constraints on the z = 1 Tully-Fisher relation
Kneib, J. -P.; Smith, Graham P.; Smail, Ian +5 more
We exploit the gravitational potential of massive cluster lenses to probe the emission-line properties of six z = 1 galaxies which appear as highly magnified luminous arcs. Using the Gemini Multi-Object Spectrograph (GMOS) integral field spectrograph together with detailed cluster lens models, we reconstruct the intrinsic morphologies and two-dime…
Where are the sources of the near-infrared background?
Ferrara, Andrea; Salvaterra, Ruben
The observed near-infrared background excess over light from known galaxies is commonly ascribed to redshifted radiation from early, very massive, Population III (Pop III) stars. We show here that this interpretation must be discarded as it largely overpredicts the number of J-dropouts and Lyα emitters in ultradeep field searches. Independently of…
Observations of magnetic anomaly signatures in Mars Express ASPERA-3 ELS data
Coates, A. J.; Kallio, E.; Fedorov, A. +40 more
Mars Express (MEX) Analyser of Space Plasmas and Energetic Atoms (ASPERA-3) data is providing insights into atmospheric loss on Mars via the solar wind interaction. This process is influenced by both the interplanetary magnetic field (IMF) in the solar wind and by the magnetic 'anomaly' regions of the martian crust. We analyse observations from th…
IGR J17252-3616: an accreting pulsar observed by INTEGRAL and XMM-Newton
Walter, R.; Stephen, J. B.; De Cesare, G. +5 more
The discovery of the X-ray source
On the nitrogen abundance of fast, low-ionization emission regions: the outer knots of the planetary nebula NGC 7009
Corradi, R. L. M.; Gonçalves, D. R.; Ercolano, B. +2 more
We have constructed a 3D photoionization model of a planetary nebula (PN) similar in structure to NGC 7009 with its outer pair of knots (also known as FLIERs - fast, low-ionization emission regions). The work is motivated by the fact that the strong [NII]λ6583 line emission from FLIERs in many PNe has been attributed to a significant local overabu…