Search Publications
The first gigayear of bulge star formation in Virgo ellipticals: constraints from their globular cluster systems
Spitler, Lee R.
Data products from the Advanced Camera for Surveys Virgo cluster survey are used to understand the bulge star formation history in early-type galaxies at redshifts z >~2. A new technique is developed whereby observed high-redshift age-metallicity relationships are utilized to constrain the typical formation epochs of metal-rich or `bulge' globu…
Study of a homogeneous QSO sample: relations between the QSO and its host galaxy
Magain, P.; Letawe, G.; Letawe, Y.
We analyse a sample of 69 quasi-stellar objects (QSOs) which have been randomly selected in a complete sample of 104 QSOs (R <= 18,0.142 < z < 0.198,δ < 10°). 60 have been observed with the NTT/SUSI2 at La Silla, through two filters in the optical band (WB 655 and V 812), and the remaining nine are taken from archive data bases. The fi…
XMM-Newton and INTEGRAL study of the SFXT IGR J18483-0311 in quiescence: hint of a cyclotron emission feature?
Sidoli, L.; Ducci, L.; Bassani, L. +2 more
We report the results from archival XMM-Newton and INTEGRAL observations of the Supergiant Fast X-ray Transient (SFXT) IGR J18483-0311 in quiescence. The 18-60 keV hard X-ray behaviour of the source is presented here for the first time; it is characterized by a spectral shape (Γ ~ 2.5) similar to that during outburst activity, and the lowest measu…
A study of the massive star-forming region M8 using images from the Spitzer Infrared Array Camera
Kumar, Dewangan Lokesh; Anandarao, B. G.
We present photometry and images (3.6, 4.5, 5.8 and 8.0 µm) from the Spitzer Infrared Array Camera (IRAC) of the star-forming region Messier 8 (M8). The IRAC photometry reveals ongoing star formation in the M8 complex, with 64 class 0/I and 168 class II sources identified in several locations in the vicinity of submm gas cores/clumps. Nearly…
A faint extended cluster in the outskirts of NGC 5128: evidence of a low mass accretion
Rejkuba, M.; Mouhcine, M.; Ibata, R. +1 more
We report the discovery of an extended globular cluster in a halo field in Centaurus A (NGC 5128), situated from the centre of that galaxy, imaged with the Advanced Camera for Surveys on board the Hubble Space Telescope. At the distance of the galaxy, the half-light radius of the cluster is rh ~ 17pc, placing it among the largest globul…
Weighing dark matter haloes with gravitationally lensed supernovae
Goobar, A.; Hook, I.; Mörtsell, E. +2 more
High-redshift Type Ia supernovae (SNe Ia) are likely to be gravitationally lensed by dark matter haloes of galaxies in the foreground. Since SNe Ia have very small dispersion after light-curve shape and colour corrections, their brightness can be used to measure properties of the dark matter haloes via gravitational magnification. We use observati…
Multifrequency nature of the 0.75 mHz feature in the X-ray light curves of the nova V4743 Sgr
Ness, J. -U.; Dobrotka, A.
We present timing analyses of eight X-ray light curves and one optical/UV light curve of the nova V4743 Sgr (2002) taken by Chandra and XMM-Newton on the following days after outburst: 50 (early hard emission phase), 180, 196, 302, 371, 526 [super soft source (SSS) phase], and 742 and 1286 (quiescent emission phase). We have studied the multifrequ…
Satellites in the field and lens galaxies: SDSS/COSMOS versus SLACS/CLASS
Mao, S.; Jackson, N.; Li, Cheng +1 more
The incidence of subgalactic level substructures is an important quantity, as it is a generic prediction of high-resolution cold dark matter (CDM) models which is susceptible to observational test. Confrontation of theory with observations is currently in an uncertain state. In particular, gravitational lens systems appear to show evidence for flu…
Malin1: interacting galaxy pair?
Moiseev, A. V.; Reshetnikov, V. P.; Sotnikova, N. Ya.
Malin1 is a unique, extraordinarily large low-surface brightness galaxy. The structure and the origins of the galaxy are poorly understood. The reason for this is the absence of detailed observational data, especially of high-resolution kinematics. In this Letter, we study the stellar kinematics of the inner part (r <= 15 kpc) of Malin1.
W…Flows along cometary tails in the Helix planetary nebula NGC 7293
Boumis, P.; Meaburn, J.
Previous velocity images which reveal flows of ionized gas along the most prominent cometary tail (from Knot 38) in the Helix planetary nebula are compared with that taken at optical wavelengths with the Hubble Space Telescope and with an image in the emission from molecular hydrogen. The flows from the second most prominent tail from Knot 14 are …