Search Publications
The treatment of mixing in core helium burning models - II. Constraints from cluster star counts
Campbell, Simon W.; Constantino, Thomas; Lattanzio, John C. +1 more
The treatment of convective boundaries during core helium burning is a fundamental problem in stellar evolution calculations. In the first paper of this series, we showed that new asteroseismic observations of these stars imply they have either very large convective cores or semiconvection/partially mixed zones that trap g modes. We probe this mix…
Shapley Supercluster Survey: ram-pressure stripping versus tidal interactions in the Shapley supercluster
Bourdin, H.; Mazzotta, P.; Haines, C. P. +4 more
We present two new examples of galaxies undergoing transformation in the Shapley supercluster core. These low-mass (M_{star }∼ 0.4-1× 10^{10} M⊙) galaxies are members of the two clusters SC 1329-313 (z ∼ 0.045) and SC 1327-312 (z ∼ 0.049). Integral-field spectroscopy complemented by imaging in the ugriK bands and in Hα narrow band is us…
Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert Galaxies - II. Warm absorber dynamics and feedback to galaxies
Dewangan, Gulab C.; Guainazzi, Matteo; Laha, Sibasish +2 more
This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high-resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile (n ∝ r-α) esti…
A free-form mass model of the Hubble Frontier Fields cluster AS1063 (RXC J2248.7-4431) with over one hundred constraints
Broadhurst, Tom; Zheng, Wei; Lam, Daniel +5 more
We derive a free-form mass distribution for the massive cluster AS1063 (z = 0.348) using the completed optical imaging from the Hubble Frontier Fields programmme. Based on a subset of 11 multiply lensed systems with spectroscopic redshift, we produce a lens model that is accurate enough to secure new multiply lensed systems, totalling over a 100 a…
A study of the circumgalactic medium at z ∼ 0.6 using damped Lyman α galaxies
Turnshek, David A.; Rao, Sandhya M.; Kulkarni, Varsha P. +6 more
We present the study of a sample of nine quasi-stellar object fields, with damped Lyman α (DLA) or sub-DLA systems at z ∼ 0.6, observed with the X-Shooter spectrograph at the Very Large Telescope. By suitably positioning the X-Shooter slit based on high spatial resolution images of Hubble Space Telescope/Advanced Camera for Surveys we are able to …
Acceleration of the universe: a reconstruction of the effective equation of state
Mukherjee, Ankan
This work is based upon a parametric reconstruction of the effective or total equation of state in a model for the Universe with accelerated expansion. The constraints on the model parameters are obtained by maximum-likelihood analysis using the supernova distance modulus data, observational Hubble data, baryon acoustic oscillation data and cosmic…
Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 at z = 1.39
Bender, Ralf; Mendel, J. Trevor; Cappellari, Michele +13 more
We analyse the sizes, colour gradients and resolved stellar mass distributions for 36 massive and passive galaxies in the cluster XMMUJ2235-2557 at z = 1.39 using optical and near-infrared Hubble Space Telescope (HST) imaging. We derive light-weighted Sérsic fits in five HST bands (I775, z850, Y105, J125…
The outburst decay of the low magnetic field magnetar SWIFT J1822.3-1606: phase-resolved analysis and evidence for a variable cyclotron feature
Mereghetti, Sandro; Esposito, Paolo; Turolla, Roberto +12 more
We study the timing and spectral properties of the low-magnetic field, transient magnetar SWIFT J1822.3-1606 as it approached quiescence. We coherently phase-connect the observations over a time-span of ∼500 d since the discovery of SWIFT J1822.3-1606 following the Swift-Burst Alert Telescope (BAT) trigger on 2011 July 14, and carried out a detail…
Extinction law in the range 0.4-4.8 µm and the 8620 Å DIB towards the stellar cluster Westerlund 1
Rubinho, M. S.; Almeida, L. A.; Damineli, A. +4 more
The young stellar cluster Westerlund 1 (Wd 1: l = 339.6°, b = -0.4°) is one of the most massive in the local Universe, but accurate parameters are pending on better determination of its extinction and distance. Based on our photometry and data collected from other sources, we have derived a reddening law for the cluster line-of-sight representativ…
Giant Metrewave Radio Telescope observations of neutral atomic hydrogen gas in the COSMOS field at z ∼ 0.37
Chengalur, Jayaram N.; Colless, Matthew; Rhee, Jonghwan +2 more
We present the results of H I spectral stacking analysis of Giant Metrewave Radio Telescope (GMRT) observations targeting the Cosmological Evolution Survey (COSMOS) field. The GMRT data cube contains 474 field galaxies with redshifts known from the zCOSMOS-bright 10 k catalogue. Spectra for the galaxies are co-added and the stacked spectrum allows…