Search Publications
The evolution of field early-type galaxies in the FDF and WHDF
Böhm, Asmus; Ziegler, Bodo L.; Fritz, Alexander
We explore the properties of 24 field early-type galaxies in the redshift range 0.20 < z < 0.75 down to MB <= -19.30 in a sample extracted from the FORS Deep Field and the William Herschel Deep Field. Target galaxies were selected on the basis of a combination of luminosity, spectrophotometric type, morphology and photometric r…
The origin of the diffuse non-thermal X-ray and radio emission in the Ophiuchus cluster of galaxies
Panessa, F.; Guerrero, M. A.; Profumo, S. +4 more
We present high-resolution 240 and 607 MHz Giant Metrewave Radio Telescope radio observations, complemented with 74 MHz archival Very Large Array radio observations of the Ophiuchus cluster of galaxies, whose radio mini-halo has been recently detected at 1400 MHz. We also present archival Chandra and XMM-Newton data of the Ophiuchus cluster. Our o…
Evidence for a magnetic neutron star in high-mass X-ray binary 4U 2206+54 with INTEGRAL/IBIS observations
Wang, Wei
The hard X-ray source 4U 2206+54 is a peculiar high-mass X-ray binary with a main-sequence donor star. Recent X-ray observations suggested that the compact object in 4U 2206+54 may be a neutron star. The X-ray emission comes from the accretion of stellar winds from the massive donor star, and variability of its luminosity may be due to changes in …
The expected detection of dust emission from high-redshift Lyman α galaxies
Finkelstein, Steven L.; Hathi, Nimish P.; Pirzkal, Norbert +2 more
Recent results have shown that a substantial fraction of high-redshift Lyman α (Lyα) galaxies contain considerable amounts of dust. This implies that Lyα galaxies are not primordial, as has been thought in the past. However, this dust has not been directly detected in emission; rather it has been inferred based on extinction estimates from rest-fr…
Star clusters in the interacting galaxy system Arp 284
Peterson, Bradley W.; Struck, Curtis; Smith, Beverly J. +1 more
We present results from a study of protoglobular cluster candidates in the interacting galaxy system Arp 284 (NGC 7714/5) using data from the Hubble Space Telescope (HST). Previous studies of the Antennae and M51 have suggested that the majority of young massive star clusters dissolve within 20 Myr due to mass loss. We use the evolutionary synthes…
The unusual 2006 dwarf nova outburst of GK Persei
Osborne, J. P.; Beardmore, A. P.; Evans, P. A. +1 more
The 2006 outburst of GK Persei differed significantly at optical and ultraviolet (UV) wavelengths from typical outbursts of this object. We present multiwavelength (X-ray, UV and optical) Swift and AAVSO data, giving unprecedented broad-band coverage of the outburst, allowing us to follow the evolution of the longer-than-normal 2006 outburst acros…
The haloes of planetary nebulae in the mid-infrared: evidence for interaction with the interstellar medium
Ramos-Larios, G.; Phillips, J. P.
The motion of planetary nebulae through the interstellar medium (ISM) is thought to lead to a variety of observational consequences, including the formation of bright rims, deformation and fragmentation of the shells, and a shift of the central stars away from the geometric centres of the envelopes. These and other characteristics have been noted …
Hard X-ray observations of PSR J1833-1034 and its associated pulsar wind nebula
de Rosa, A.; Ubertini, P.; Bassani, L. +3 more
PSR J1833-1034 and its associated pulsar wind nebula (PWN) have been investigated in depth through X-ray observations ranging from 0.1 to 200 keV. The low-energy X-ray data from Chandra reveal a complex morphology that is characterized by a bright central plerion, no thermal shell and an extended diffuse halo. The spectral emission from the centra…
Optical spectroscopy of the quiescent counterpart to EXO0748-676
Torres, M. A. P.; Steeghs, D.; Bassa, C. G. +1 more
We present phase resolved optical spectroscopy and X-ray timing of the neutron star X-ray binary EXO0748-676 after the source returned to quiescence in the autumn of 2008. The X-ray light curve displays eclipses consistent in orbital period, orbital phase and duration with the predictions and measurements before the return to quiescence. Hα and He…
Studying X-ray reprocessing and continuum variability in quasars: PG 1211+143
Bachev, R.; Semkov, E.; Gallo, L. C. +5 more
We present the results from a monitoring campaign of the Narrow-Line Seyfert 1 galaxy PG 1211+143. The object was monitored with ground-based facilities (UBVRI photometry; from 2007 February to July) and with Swift [X-ray photometry/spectroscopy and ultraviolet (UV)/optical photometry; between 2007 March and May]. We found PG 1211+143 in a histori…