Search Publications
On the nitrogen abundance of fast, low-ionization emission regions: the outer knots of the planetary nebula NGC 7009
Corradi, R. L. M.; Gonçalves, D. R.; Ercolano, B. +2 more
We have constructed a 3D photoionization model of a planetary nebula (PN) similar in structure to NGC 7009 with its outer pair of knots (also known as FLIERs - fast, low-ionization emission regions). The work is motivated by the fact that the strong [NII]λ6583 line emission from FLIERs in many PNe has been attributed to a significant local overabu…
The quest for Type 2 quasars: Chandra observations of luminous obscured quasars in the Sloan Digital Sky Survey
Comastri, Andrea; Vignali, Cristian; Alexander, Dave M.
We report on new Chandra exploratory observations of six candidate Type 2 quasars at z = 0.49-0.73 selected among the most [OIII] luminous emitters from the Sloan Digital Sky Survey (SDSS). Under the assumption that [OIII] is a proxy for the intrinsic luminosity of the central source, their predicted rest-frame X-ray luminosities are L2-10keV…
Solar FLAG hare and hounds: on the extraction of rotational p-mode splittings from seismic, Sun-as-a-star data
Baudin, F.; Jiménez-Reyes, S. J.; García, R. A. +18 more
We report on results from the first solar Fitting at Low-Angular degree Group (solar FLAG) hare-and-hounds exercise. The group is concerned with the development of methods for extracting the parameters of low-l solar p-mode data (`peak bagging'), collected by Sun-as-a-star observations. Accurate and precise estimation of the fundamental parameters…
Cross-correlation of Lyman α absorbers with gas-rich galaxies
Ryan-Weber, Emma V.
The HI Parkes all-sky survey (HIPASS) galaxy catalogue is cross-correlated with known low redshift, low column density (NHI < 1015cm-2) Lyman α (Lyα) absorbers from the literature. The redshift-space correlation is found to be similar in strength to HIPASS galaxy self-clustering (correlation length s0,ag
X-ray spectra of sources in the 13H XMM-Newton/Chandra deep field
McHardy, I.; Page, M. J.; Seymour, N. +8 more
We present the X-ray spectra of 86 optically identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The majority of these sources have 2-10keV fluxes between 10-15 and 5 × 10-14ergcm-2s-1. The sample consists of 50 broad-line active galactic nuclei (BLAGN),…
Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1
Warwick, R. S.; Roberts, T. P.; Ward, M. J. +2 more
We report the results of a two-month campaign conducted with the Chandra X-ray observatory to monitor the ultraluminous X-ray source (ULX) NGC 5204 X-1. This was composed of a 50-ks observation, followed by ten 5-ks follow-ups spaced initially at ~3, then at ~10-d intervals. The ULX flux is seen to vary by factors ~5 on time-scales of a few days, …
INTEGRAL and XMM-Newton observations of the X-ray pulsar IGR J16320-4751/AX J1631.9-4752
Petrucci, P. -O.; Tomsick, J. A.; Rodriguez, J. +16 more
We report on observations of the X-ray pulsar IGR J16320-4751 (also known as AX J1631.9-4752) performed simultaneously with International Gamma-Ray Astrophysics Laboratory (INTEGRAL) and XMM-Newton. We refine the source position and identify the most likely infrared counterpart. Our simultaneous coverage allows us to confirm the presence of X-ray …
Mapping stellar kinematics across the Galactic bar: HST measurements of proper motions in 35 fields
Kozłowski, S.; Mao, S.; Wyrzykowski, Ł. +4 more
We present a proper motion mini-survey of 35 fields in the vicinity of Baade window, (l, b) = (1°, -4°), sampling roughly a 5 × 2.5-deg2 region of the Galactic bar. Our second epoch observations collected with the Advanced Camera for Surveys/High Resolution Channel instrument onboard the Hubble Space Telescope were combined with the arc…
Gemini/GMOS spectra of globular clusters in the Virgo giant elliptical NGC 4649
Forbes, Duncan A.; Beasley, Michael A.; Zepf, Stephen E. +8 more
NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have obtained Gemini/GMOS (Gemini North Multi-Object Spectrograph) spectra for 38 globular clusters (GCs) associated with this galaxy. Applying the multi-index χ2 minimization technique of Proctor and Sansom with the single stellar population models of Thomas, Maraston an…
SCUBA observations of the Horsehead nebula - what did the horse swallow?
Bontemps, S.; Ward-Thompson, D.; Nutter, D. +2 more
We present observations taken with the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT) of the Horsehead nebula in Orion (B33), at wavelengths of 450 and 850 µm. We see bright emission from that part of the cloud associated with the photon-dominated region (PDR) at the `top' of the horse's head, w…