Search Publications
Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
Williams, Benjamin F.; Lauer, Tod R.; Dalcanton, Julianne J. +5 more
We explore the assembly history of the M31 bulge within a projected major-axis radius of 180 arcsec (∼680 pc) by studying its stellar populations in Hubble Space Telescope Wide Field Camera 3 and Advanced Camera for Surveys observations. Colours formed by comparing near-ultraviolet versus optical bands are found to become bluer with increasing maj…
Detection of fundamental and first harmonic cyclotron line in X-ray pulsar Cep X-4
Naik, Sachindra; Jaisawal, Gaurava K.
We report the broad-band spectral properties of the X-ray pulsar Cep X-4 by using a Suzaku observation in 2014 July. The 0.8-70 keV spectrum was found to be well described by three continuum models - Negative and Positive power-law with Exponential cut-off (NPEX), high-energy cut-off power-law and CompTT models. Additional components such as a cyc…
The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216
Cernicharo, J.; Fonfría, J. P.; Richter, M. J. +3 more
We present high spectral resolution mid-IR observations of SiS towards the C-rich AGB star IRC+10216 carried out with the Texas Echelon-cross-Echelle Spectrograph mounted on the NASA Infrared Telescope Facility. We have identified 204 ro-vibrational lines of 28Si32S, 26 of 29Si32S, 20 of 28Si<…
H-ATLAS/GAMA and HeViCS - dusty early-type galaxies in different environments
Ivison, R. J.; De Looze, I.; Baes, M. +21 more
The Herschel Space Observatory has had a tremendous impact on the study of extragalactic dust. Specifically, early-type galaxies (ETG) have been the focus of several studies. In this paper, we combine results from two Herschel studies - a Virgo cluster study Herschel Virgo Cluster Survey (HeViCS) and a broader, low-redshift Herschel-Astrophysical …
Systematic characterization of the Herschel SPIRE Fourier Transform Spectrometer
Valtchanov, I.; Clements, D. L.; Spencer, L. D. +17 more
A systematic programme of calibration observations was carried out to monitor the performance of the Spectral and Photometric Imaging REceiver (SPIRE) Fourier Transform Spectrometer (FTS) instrument on board the Herschel Space Observatory. Observations of planets (including the prime point-source calibrator, Uranus), asteroids, line sources, dark …
Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters
De Grandi, S.; Gastaldello, F.; Jiménez-Bailón, E. +11 more
We present the first pointed X-ray observations of 10 candidate fossil galaxy groups and clusters. With these Suzaku observations, we determine global temperatures and bolometric X-ray luminosities of the intracluster medium (ICM) out to r500 for six systems in our sample. The remaining four systems show signs of significant contaminati…
A Suzaku view of IGR J16393-4643
Maitra, Chandreyee; Paul, Biswajit; Pradhan, Pragati +1 more
The pulsar IGR J16393-4643 belongs to a class of highly absorbed supergiant high-mass X-ray binaries (HMXBs), characterized by a very high column density of absorbing matter. We present the results of simultaneous broad-band pulsation and spectrum analysis from a 44-ks Suzaku observation of the source. The orbital intensity profile created with th…
Nuclear star cluster formation in energy-space
Böker, Torsten; Georgiev, Iskren Y.; den Brok, Mark +2 more
In a virialized stellar system, the mean-square velocity is a direct tracer of the energy per unit mass of the system. Here, we exploit this to estimate and compare root-mean-square velocities for a large sample of nuclear star clusters and their host (late- or early-type) galaxies. Traditional observables, such as the radial surface brightness an…
H-ATLAS/GAMA: quantifying the morphological evolution of the galaxy population using cosmic calorimetry
Baes, Maarten; Smith, M. W. L.; Graham, Alister W. +28 more
Using results from the Herschel Astrophysical Terrahertz Large-Area Survey (H-ATLAS) and the Galaxy and Mass Assembly (GAMA) project, we show that, for galaxy masses above ≃ 108 M⊙, 51 per cent of the stellar mass-density in the local Universe is in early-type galaxies (ETGs; Sérsic n > 2.5) while 89 per cent of the rate o…
Probing large-scale wind structures in Vela X-1 using off-states with INTEGRAL
Sidoli, L.; Bozzo, E.; Pottschmidt, K. +4 more
Vela X-1 is the prototype of the class of wind-fed accreting pulsars in high-mass X-ray binaries hosting a supergiant donor. We have analysed in a systematic way 10 years of INTEGRAL data of Vela X-1 (22-50 keV) and we found that when outside the X-ray eclipse, the source undergoes several luminosity drops where the hard X-rays luminosity goes bel…