Search Publications
XMM-Newton and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift
Georgakakis, A.; Hatziminaoglou, E.; Georgantopoulos, I. +2 more
We combine bright XMM-Newton data with the Chandra Deep Field South observations to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity. Our sample consists of 359 sources selected in the hard 2-8 keV band, spanning the flux range 6 × 10-16-3 × 10-13 erg~cm-2~s-1
Constraints on dark matter and the shape of the Milky Way dark halo from the 511-keV line
Knödlseder, J.; Jean, P.; Ascasibar, Y. +1 more
About one year ago, it was speculated that decaying or annihilating light dark matter (LDM) particles could explain the flux and extension of the 511-keV line emission in the Galactic Centre. Here, we present a thorough comparison between theoretical expectations of the Galactic positron distribution within the LDM scenario and observational data …
Carbon dioxide photoelectron energy peaks at Mars
Coates, A. J.; Kallio, E.; Fedorov, A. +40 more
The ELectron Spectrometer (ELS) from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) flown on the Mars Express spacecraft has an 8% energy resolution, combined with the capability to oversample the martian electron distribution. This makes possible the resolution and identification of electrons generated as a result of the He 304 Å io…
Finding benchmark brown dwarfs to probe the substellar initial mass function as a function of time
Steele, I. A.; Pinfield, D. J.; Kendall, T. R. +5 more
Using a simulated disc brown dwarf (BD) population, we find that new large area infrared surveys are expected to identify enough BDs covering wide enough mass-age ranges to potentially measure the present day mass function down to ~0.03Msolar, and the BD formation history out to 10Gyr, at a level that will be capable of establishing if …
Multiwavelength Observations of GRB 050820A: An Exceptionally Energetic Event Followed from Start to Finish
Cenko, S. B.; Price, P. A.; Harrison, F. A. +24 more
We present observations of the unusually bright and long γ-ray burst GRB 050820A, one of the best sampled broadband data sets in the Swift era. The γ-ray light curve is marked by a soft precursor pulse some 200 s before the main event; the lack of any intervening emission suggests that it is due to a physical mechanism distinct from the GRB itself…
Probing Cosmic Star Formation Using Long Gamma-Ray Bursts: New Constraints from the Spitzer Space Telescope
Armus, Lee; Le Floc'h, Emeric; Mirabel, I. Félix +3 more
We report on IRAC 4.5 µm, IRAC 8.0 µm, and MIPS 24 µm deep observations of 16 gamma-ray burst (GRB) host galaxies performed with the Spitzer Space Telescope, and we investigate in the thermal infrared the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with these objects. Our sample is…
Late-type galaxies observed with SAURON: two-dimensional stellar and emission-line kinematics of 18 spirals
Emsellem, Eric; Peletier, Reynier F.; Cappellari, Michele +5 more
We present the stellar and gas kinematics of a sample of 18 nearby late-type spiral galaxies (Hubble types ranging from Sb to Sd), observed with the integral-field spectrograph SAURON at the 4.2-m William Herschel Telescope. SAURON covers the spectral range 4800-5380Å, allowing us to measure the Hβ, Fe, Mgb absorption features and the emission in …
Observational Evidence of Gentle Chromospheric Evaporation during the Impulsive Phase of a Solar Flare
Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis +1 more
Observational evidence of gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory. Until now, evidence of gentle evaporation has often been reported …
The structure of flux transfer events recovered from Cluster data
Balogh, A.; Klecker, B.; Owen, C. J. +4 more
The structure and formation mechanism of a total of five Flux Transfer Events (FTEs), encountered on the equatorward side of the northern cusp by the Cluster spacecraft, with separation of ~5000 km, are studied by applying the Grad-Shafranov (GS) reconstruction technique to the events. The technique generates a magnetic field/plasma map of the FTE…
Evolution of the Color-Magnitude Relation in High-Redshift Clusters: Early-Type Galaxies in the Lynx Supercluster at z ~ 1.26
Franx, Marijn; Illingworth, Garth D.; Postman, Marc +10 more
Color-magnitude relations (CMRs) have been derived in two high-redshift clusters, RX J0849+4452 and RX J0848+4453 (with redshifts of z=1.26 and 1.27, respectively), that lie in the highest redshift cluster superstructure known today, the Lynx Supercluster. The CMR was determined from ACS imaging in the WFC F775W (i775) and F850LP (z