Search Publications
The orthogonally aligned dark halo of an edge-on lensing galaxy in the Hubble Frontier Fields: a challenge for modified gravity
Broadhurst, Tom; Lam, Daniel; Lim, Jeremy +2 more
We examine a well-resolved lensed image that is bent by an edge-on lenticular galaxy, in the Hubble Frontier Fields (HFF) data of MACSJ0416.1-20403. The fortuitous combination of a long arc (zs ≈ 1 ± 0.2) intersecting an edge-on galaxy from the cluster (z = 0.4) provides an opportunity to constrain its dark matter (DM) halo and its orie…
A comprehensive HST BVI catalogue of star clusters in five Hickson compact groups of galaxies
Bastian, N.; Konstantopoulos, I. S.; Gallagher, S. C. +5 more
We present a photometric catalogue of star cluster candidates in Hickson compact groups (HCGs) 7, 31, 42, 59, and 92, based on observations with the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope. The catalogue contains precise cluster positions (right ascension and declination), magnitudes, and colours in th…
Weak lensing by minifilament or minivoid as the origin of flux-ratio anomalies in lensed quasar MG0414+0534
Inoue, Kaiki Taro
We explore the weak lensing effects by ministructures in the line of sight in a quadruply lensed quasar MG0414+0534 that shows an anomaly in the flux ratios. We find that the observed flux-ratio anomaly can be explained by a presence of either a minifilament or a minivoid in the line of sight with a surface mass density of the order of 108-9<…
Exploring the potential X-ray counterpart of the puzzling TeV gamma-ray source HESS J1507-622 with new Suzaku observations
Eger, P.; Hahn, J.; Domainko, W. F.
The unidentified very high energy (VHE, E > 100 GeV) gamma-ray source HESS J1507-622 seems to not fit into standard models for sources related to young supernova remnants, pulsar wind nebulae, or young stellar populations in general. This is due to its intrinsically extended, but yet compact morphology, coupled with a relative large offset (∼3.…
Study of X-ray emission from the old open cluster, M67
Singh, K. P.; Mooley, K. P.
We present an X-ray analysis of a 4 Gyr old open cluster, M67, using archival XMM-Newton data. The aim of this study was to find new X-ray members of M67, and to use the updated member list for studying X-ray variability, and derive the X-ray luminosity functions (XLFs) of different stellar types and compare them with other star clusters of simila…
A spatial-correlation analysis of the cubic 3-torus topology based on the Planck 2013 data
Aurich, R.
Spatial correlations of the cubic 3-torus topology are analysed using the Planck 2013 data. The spatial-correlation method for detecting multiply connected spaces is based on the fact that positions on the cosmic microwave background (CMB) sky, that are separated by large angular distances, can be spatially much nearer according to a hypothesized …
Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz
Dickinson, C.; Pearson, T. J.; Readhead, A. C. S. +6 more
Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimizing the contamination in cosmological measurements. Motivated by this, we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at ∼4.5 arcmin resol…
Modelling warm absorption in HST/COS spectrum of Mrk 290 with XSTAR
Kriss, G. A.; Kallman, T. R.; Zhang, S. N. +4 more
We present a new method to model an HST/COS (Hubble Space Telescope/Cosmic Origins Spectrograph) spectrum, aimed to analyse intrinsic UV absorption from the outflow of Mrk 290, a Seyfert I galaxy. We use newly updated XSTAR to generate photoionization models for the intrinsic absorption from the active galactic nuclei (AGN) outflow, the line emiss…
Young star clusters in the interacting galaxies of Hickson Compact Group 90
Sharples, R. M.; Cho, J.; Miah, J. A.
Deep images of Hickson Compact Group 90 (HCG 90) have been obtained using the Advanced Camera for Surveys on the Hubble Space Telescope. We report results for star clusters observed in the interacting pair of galaxies NGC 7174 and NGC 7176. We present magnitude and colour distributions for the observed cluster population and find that the majority…
LMC S63: a historical reappraisal of the outburst behaviour of a deeply eclipsing Magellanic symbiotic star
Gromadzki, Mariusz; Miszalski, Brent; Iłkiewicz, Krystian +2 more
We present an analysis of multi-epoch low-resolution spectrophotometry, complemented by the light curves provided by massive photometric surveys spanning over 100 yr, of the symbiotic binary LMC S63. We showed that it is an eclipsing binary with the orbital period of 1050 d. We also found evidence of outbursts in history of the white dwarf. If it …