Search Publications
Detection of type 2 quasars in the radio galaxies B3 0731+438 and 3C 257
O'Brien, P. T.; Reeves, J. N.; Ward, M. J. +3 more
We present XMM-Newton observations and spectral fitting of two high-redshift, [OIII]-luminous, narrow-line radio galaxies, B3 0731+438 and 3C 257. Their X-ray continua are well fitted by a partial covering model with intrinsically unabsorbed and absorbed power-law components. The spectral models indicate that both objects harbour highly obscured n…
Formation of bulges in very late-type galaxies from super star clusters
Deng, Z. G.; Fu, Y. N.; Huang, J. H.
The dynamical evolution of super star clusters (SSCs) moving in the background of a dark matter halo has been investigated as a possible event responsible for the formation of bulges in late-type spirals. The underlying physical processes include sinking of SSCs due to the dynamical friction and stripping of SSCs on their way to the centre. Our mo…
An XMM-Newton observation of the narrow-line Seyfert 1 galaxy Markarian 896
O'Brien, P. T.; Reeves, J. N.; Page, K. L. +1 more
We present XMM-Newton observations of the narrow-line Seyfert 1 galaxy Markarian 896. Over the 2-10 keV band, an iron emission line, close to 6.4 keV, is seen. The line is just resolved and has an equivalent width of ~170 eV. The broad-band spectrum is well modelled by a power-law slope of Γ~ 2.03, together with two blackbody components to fit the…
Stellar collisions in galactic centres: black hole growth and colour gradients
Yu, Qingjuan
We study the effects of stellar collisions, particularly on feeding massive black holes (BHs) and colour gradients, in realistic galactic centres. We find that the mass released by stellar collisions is not sufficient to account for the present BH mass in galactic centres, especially in bright galaxies. This study, together with the study by Magor…
A high-resolution radio study of neutral gas in the starburst galaxy NGC 520
Beswick, R. J.; Pedlar, A.; Clemens, M. S. +1 more
We present subarcsec angular resolution observations of the neutral gas in the nearby starburst galaxy NGC 520. The central kpc region of NGC 520 contains an area of significantly enhanced star formation. The radio continuum structure of this region resolves into ~10 continuum components. By comparing the flux densities of the brightest of these c…
`Hyper-parameters' approach to joint estimation: applications to Cepheid-calibrated distances and X-ray clusters
Lahav, Ofer; Ettori, Stefano; Erdogdu, Pirin
We use a generalized procedure for the combined likelihood analysis of different cosmological probes, the `hyper-parameters' method, that allows freedom in the relative weights of the raw measurements. We perform a joint analysis of the Cepheid-calibrated data from the Hubble Space Telescope Key Project and the baryon mass fraction in clusters to …
Chromospheric activity and unique solution of SZ Psc
Kang, Young Woon; Lee, Woo-Baik; Kim, Ho-il +1 more
We have confirmed that the MgII h and k emission lines of SZ Psc are mainly enhanced by the K subgiant component of the system, using the radial velocities reduced from the emission lines. The intensity variation of the emission line is correlated with the orbital phase of SZ Psc. The shape of light curves of SZ Psc were changing every season. The…
Measurement of the Sunyaev-Zel'dovich increment in massive galaxy clusters
Halpern, Mark; Pierpaoli, Elena; Chapman, Scott +4 more
We have detected the Sunyaev-Zel'dovich (SZ) increment at 850 µm in two galaxy clusters (Cl 0016+16 and MS 1054.4-0321) using the Submillimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Fits to the isothermal β model yield a central Compton y parameter of (2.2 +/- 0.7) × 10-4 and a central 850-&micr…
The sensitivity of the seismic solar model to Newton's constant
Silk, Joseph; Lopes, Ilídio P.
New experimental determinations of Newton's gravitational constant have been recently given. There are significant disagreements between these new measurements. We show that the high accuracy obtained with current standard solar models is such that the uncertainties in core temperature profiles arising from the uncertainties in G can be comparable…
Probing the extended emission-line region in 3C 171 with high-frequency radio polarimetry
Hardcastle, M. J.
I present high-frequency polarimetric radio observations of the radio galaxy 3C 171, in which depolarization is associated with an extended emission-line region. The radio hotspots, known to be depolarized at low radio frequencies, become significantly polarized above (observer's frame) frequencies of 15 GHz. There is some evidence that some of th…