Search Publications
The kinematic footprints of five stellar streams in Andromeda's halo
Tanvir, N.; Rich, R. M.; Koch, A. +12 more
We present a spectroscopic analysis of five stellar streams (`A', `B', `Cr', `Cp' and `D') as well as the extended star cluster, EC4, which lies within Stream`C', all discovered in the halo of M31 from our Canada-France-Hawaii Telescope/MegaCam survey. These spectroscopic results were initially serendipitous, making use of our existing observation…
The faint and extremely red K-band-selected galaxy population in the DEEP2/Palomar fields
Conselice, C. J.; Bundy, K.; Lotz, J. +3 more
We present in this paper an analysis of the faint and red near-infrared (NIR) selected galaxy population found in NIR imaging from the Palomar Observatory Wide-Field Infrared Survey. This survey covers 1.53 deg2 to 5σ detection limits of Kvega = 20.5-21 and Jvega = 22.5, and overlaps with the DEEP2 spectroscopic re…
X-ray variability of the Seyfert 1 Markarian 335: power spectrum and time lags
Arévalo, P.; McHardy, I. M.; Summons, D. P.
To investigate further the comparison between active galactic nuclei (AGN) and black hole X-ray binaries, we have studied the main X-ray variability properties of the Seyfert 1 galaxy Mrk 335. We put particular emphasis on the X-ray time lags, which is a potentially important diagnostic of physical models. From a 100 ks observation by XMM-Newton, …
On the nature of unabsorbed Seyfert 2 galaxies
Nandra, Kirpal; Brightman, Murray
We present an analysis of six 12µm selected Seyfert 2 galaxies that have been reported to be unabsorbed in the X-ray. By comparing the luminosities of these galaxies in the mid-infrared (12µm), optical ([OIII]) and hard X-ray (2-10keV), we show that they are all underluminous in the 2-10keV X-ray band. Four of the objects exhibit X-ray…
Anatomy of a young massive star cluster: NGC 1569-B
Larsen, S. S.; Gallagher, J. S.; Origlia, L. +1 more
We present new H-band echelle spectra, obtained with the NIRSPEC spectrograph at Keck II, for the massive star cluster `B' in the nearby dwarf irregular galaxy NGC 1569. From spectral synthesis and equivalent width measurements, we obtain abundances and abundance patterns. We derive an Fe abundance of [Fe/H] = -0.63 +/- 0.08, a supersolar [α/Fe] a…
Structural parameters for globular clusters in NGC 5128 - III. ACS surface brightness profiles and model fits
Forbes, Duncan A.; Barmby, Pauline; Harris, William E. +2 more
We present internal surface brightness profiles, based on Hubble Space Telescope/ACS imaging in the F606W bandpass, for 131 globular cluster (GC) candidates with luminosities L ~= 104-3 × 106Lsolar in the giant elliptical galaxy NGC 5128. Several structural models are fitted to the profile of each cluster and combi…
A search for the progenitors of two TypeIa Supernovae in NGC 1316
Maoz, Dan; Mannucci, Filippo
Recent evidence of a young progenitor population for many TypeIa supernovae (SNeIa) raises the possibility that evolved intermediate-mass progenitor stars may be detected in pre-explosion images. NGC 1316, a radio galaxy in the Fornax cluster, is a prolific producer of SNeIa, with four detected since 1980. We analyse Hubble Space Telescope (HST) p…
On the evidence for narrow, relativistically shifted X-ray lines
Vaughan, S.; Uttley, P.
In recent years, there have been many reported detections of highly redshifted or blueshifted narrow spectral lines (both emission or absorption) in the X-ray spectra of active galaxies, but these are all modest detections in terms of their statistical significance. The aim of this paper is to review the issue of the significance of these detectio…
Keck spectroscopy of the faint dwarf elliptical galaxy population in the Perseus Cluster core: mixed stellar populations and a flat luminosity function
Conselice, Christopher J.; Penny, Samantha J.
We present the result of a photometric and Keck low-resolution imaging spectrometer (LRIS) spectroscopic study of dwarf galaxies in the core of the Perseus Cluster, down to a magnitude of MB = -12.5. Spectra were obtained for 23 dwarf-galaxy candidates, from which we measure radial velocities and stellar population characteristics from …
Multifrequency VLA observations of the FR I radio galaxy 3C 31: morphology, spectrum and magnetic field
Giovannini, G.; Parma, P.; Laing, R. A. +4 more
We present high-quality Very Large Array (VLA) images of the Fanaroff-Riley Class I (FRI) radio galaxy 3C31 in the frequency range 1365-8440MHz with angular resolutions from 0.25 to 40 arcsec. Our new images reveal complex, well resolved filamentary substructure in the radio jets and tails. We also use these images to explore the spectral structur…