Search Publications
INTEGRAL results on supergiant fast X-ray transients and accretion mechanism interpretation: ionization effect and formation of transient accretion discs
Sidoli, L.; Ducci, L.; Paizis, A.
We performed a systematic analysis of all INTEGRAL observations from 2003 to 2009 of 14 supergiant fast X-ray transients (SFXTs), implying a net exposure time of about 30 Ms. For each source we obtained light curves and spectra (3-100 keV), discovering several new outbursts. We discuss the X-ray behaviour of SFXTs emerging from our analysis in the…
Spectral variability and reverberation time delays in the Suzaku X-ray spectrum of NGC 4051
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +3 more
Long-exposure Suzaku X-ray observations of the nearby active galaxy NGC 4051 from 2005 and 2008 are analysed, in an attempt to reach a self-consistent understanding of both the spectral variability on long time-scales and the broad-band variability at high time resolution. The techniques of principal components analysis and a maximum likelihood me…
A study of interstellar gas and stars in the gravitationally lensed galaxy `the Cosmic Eye' from rest-frame ultraviolet spectroscopy
Pettini, Max; Shapley, Alice E.; Steidel, Charles C. +2 more
We report the results of a study of the rest-frame ultraviolet (UV) spectrum of the Cosmic Eye (J213512.73-010143), a luminous (L ~ 2L*) Lyman break galaxy at zsys = 3.07331 magnified by a factor of ~25 via gravitational lensing by foreground mass concentrations at z = 0.73 and 0.33. The spectrum, recorded at high resolution and signal-…
Metal transport by gas sloshing in M87
Böhringer, H.; Simionescu, A.; Churazov, E. +5 more
We present the results of an XMM-Newton mosaic covering the central ~200kpc of the nearby Virgo cluster. We focus on a strong surface brightness discontinuity in the outskirts of the brightest cluster galaxy (BCG), M87. Using both XMM-Newton and Suzaku, we derive accurate temperature and metallicity profiles across this feature and show that it is…
Quantifying dwarf satellites through gravitational imaging: the case of SDSSJ120602.09+514229.5
Czoske, Oliver; Koopmans, Léon V. E.; Vegetti, Simona
SDSSJ120602.09+514229.5 is a gravitational lens system formed by a group of galaxies at redshift zFG = 0.422 lensing a bright background galaxy at redshift zBG = 2.001. The main peculiarity of this system is the presence of a luminous satellite near the Einstein radius, which slightly deforms the giant arc. This makes SDSSJ12…
Excess AGN activity in the z = 2.30 Protocluster in HS 1700+64
Georgakakis, A.; Nandra, K.; Aird, J. +7 more
We present the results of spectroscopic, narrow-band and X-ray observations of a z = 2.30 protocluster in the field of the QSO HS 1700+643. Using a sample of BX/MD galaxies, which are selected to be at z ~ 2.2-2.7 by their rest-frame ultraviolet colours, we find that there are five protocluster AGN which have been identified by characteristic emis…
IC 2602: a lithium depletion boundary age and new candidate low-mass stellar members
Sharp, R. G.; Lodieu, N.; Dobbie, P. D.
We report the results from a photometric and spectroscopic survey of ∼1.4 deg2 of the young open cluster IC 2602. Fourteen objects have been identified as having magnitudes, spectral types and radial velocities consistent with being probable or possible low-mass stellar members of the cluster. We have used the observed location of the l…
Towards a fully consistent Milky Way disc model - I. The local model based on kinematic and photometric data
Jahreiß, H.; Just, A.
We present a fully consistent evolutionary disc model of the solar cylinder. The model is based on a sequence of stellar subpopulations described by the star formation history (SFR) and the dynamical heating law [given by the age-velocity dispersion relation (AVR)]. The stellar subpopulations are in dynamical equilibrium and the gravitational pote…
Clumpy galaxies at z ~ 0.6: kinematics, stability and comparison with analogues at other redshifts
Puech, M.
Distant clumpy galaxies are thought to be Jeans-unstable discs and an important channel for the formation of local galaxies, as suggested by recent spatially resolved kinematic observations of z ~ 2 galaxies. I study the kinematics of clumpy galaxies at z ~ 0.6 and compare their properties with those of counterparts at higher and lower redshifts. …
The X-ray spectrum of the newly discovered accreting millisecond pulsar IGR J17511-3057
Papitto, A.; Burderi, L.; Bozzo, E. +5 more
We report on a 70 ks XMM-Newton Target of Opportunity (ToO) observation of the newly discovered accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1)Hz are observed throughout the outburst with an rms-pulsed fraction of 14.4(3) per cent. Pulsations have been used to derive a precise solution for the Porb = 12487.51…