Search Publications
`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…
The deuterium abundance in the z= 0.7 absorber towards QSO PG1718+4807
Webb, J. K.; Carswell, R. F.; Lanzetta, K. M. +1 more
We report on a further analysis of the ratio of deuterium to hydrogen (D/H) using Hubble Space Telescope (HST) spectra of the z= 0.701 Lyman limit system towards the quasi-stellar object (QSO) PG1718+481. Initial analyses of this absorber found it gave a high D/H value, 1.8-3.1 × 10-4, inconsistent with several higher redshift measureme…
HST and UKIRT imaging observations of z~ 1 6C radio galaxies - I. The data
Eales, S.; Rawlings, S.; Röttgering, H. J. A. +3 more
The results of Hubble Space Telescope and UKIRT imaging observations are presented for a sample of 11 6C radio galaxies with redshifts 0.85 < z < 1.5. The observations of the 6C sources reveal a variety of different features, similar to those observed around the higher power 3CR sources of similar redshifts. However, the extent and luminosit…
A triple nucleus in the brightest cluster galaxy in Abell 193
Seigar, Marc S.; Lynam, Paul D.; Chorney, Nicole E.
We present a ground-based, near-infrared, K-band image and a Hubble Space Telescope (HST) WFPC2 image of the brightest cluster galaxy in Abell 193 (IC 1695). This object was selected as the central cluster galaxy using X-ray information. Both images reveal a triple nucleus structure. Previously, this galaxy was thought to have only two nuclei. We …
The warm absorber of the type 1 Seyfert galaxy H1419+480
Barcons, X.; Carrera, F. J.; Ceballos, M. T.
The bright type 1 Seyfert galaxy H1419+480 (z~ 0.072), whose X-ray colours from earlier HEAO-1 and ROSAT missions suggested a complex X-ray spectrum, has been observed with XMM-Newton. The EPIC spectrum above 2 keV is well fitted by a power law with photon index Γ= 1.84 +/- 0.01 and an Fe Kα line of equivalent width ~250 eV. At softer energies, a …
Balmer absorption variability and the disc wind of V592 Cassiopeiae
Prinja, R. K.; Wagner, R. M.; Howell, S. B. +1 more
We present results from time-series optical spectroscopy of the low-inclination, nova-like cataclysmic variable, V592 Cas. The data span the wavelength range from ~4000 to 5000 Å, and include Balmer lines (Hβ to Hɛ) as well as He I and He II. The Balmer lines are generally characterized by shallow absorption troughs with superimposed narrower cent…