Search Publications
The X-rays wind connection in PG 2112+059
Bauer, F. E.; Brandt, W. N.; Chartas, G. +4 more
We study the connection between the X-ray and ultraviolet (UV) properties of the broad absorption line (BAL) wind in the highly X-ray variable quasar PG 2112+059 by comparing Chandra-ACIS data with contemporaneous UV HST/STIS spectra in three different epochs. We observe a correlation whereby an increase in the equivalent widths (EWs) of the BALs …
Ultraluminous X-ray sources in seven edge-on spiral galaxies
Kundu, Arunav; Strader, Jay; Dage, Kristen C. +8 more
We investigate a sample of seven edge-on spiral galaxies using Chandra observations. Edge-on spiral galaxies allow us to clearly separate source associated with their star-forming regions versus the outer edges of the system, offering a clear advantage over other systems. We uncover a number of X-ray point sources across these galaxies, and after …
Jupiter's X-ray aurora during UV dawn storms and injections as observed by XMM-Newton, Hubble, and Hisaki
Coates, A. J.; Branduardi-Raymont, G.; Bonfond, B. +9 more
We present results from a multiwavelength observation of Jupiter's northern aurorae, carried out simultaneously by XMM-Newton, the Hubble Space Telescope (HST), and the Hisaki satellite in 2019 September. HST images captured dawn storms and injection events in the far-ultraviolet aurora several times during the observation period. Magnetic reconne…
Modelling X-ray RMS spectra II: the ultrafast outflow of PDS 456
Reeves, J. N.; Alston, W. N.; Matzeu, G. A. +6 more
We present an improved model for excess variance spectra describing ultrafast outflows and successfully apply it to the luminous ($L_{\rm bol}\sim 10^{47}\mathrm{erg}\, \mathrm{s}^{-1}$) low-redshift (z = 0.184) quasar Pico del Dias Survey (PDS) 456. The model is able to account well for the broadening of the spike-like features of these outflows …
Exotic image formation in strong gravitational lensing by clusters of galaxies - I. Cross-section
Meena, Ashish Kumar; Bagla, Jasjeet Singh
In a recent paper, we have discussed the higher order singularities in gravitational lensing. We have shown that a singularity map, comprising A3- lines and unstable (point) singularities (A4 and D4), is a compact representation of high magnification regions corresponding to a given lens model for all possible sour…
Optical and NIR spectroscopy of cool CEMP stars to probe the nucleosynthesis in low-mass AGB binary system
Ojha, D. K.; Sivarani, T.; Ninan, J. P. +4 more
We present the abundance analyses of seven carbon enhanced metal-poor (CEMP) stars to understand the origin of carbon in them. We used high-resolution optical spectra to derive abundances of various elements. We also used low-resolution near-infrared (NIR) spectra to derive the abundance of O and 12C/13C from the CO molecular…
The Hercules cluster in X-rays with XMM-Newton and Chandra
Singh, Kulinder Pal; Tiwari, Juhi
We present a detailed X-ray study of the central subcluster of the nearby ( $z\, \sim$ 0.0368) Hercules cluster (Abell 2151) identified as A2151C that shows a bimodal structure. A bright clump of hot gas with X-ray emission extending to radius $r\, \sim$ 304 kpc and $L_X = 3.03_{-0.04}^{+0.02}\times 10^{43}$ erg s-1 in the 0.4-7.0 keV e…
RGB photometric calibration of 15 million Gaia stars
Cardiel, Nicolás; Zamorano, Jaime; Masana, Eduard +6 more
Although a catalogue of synthetic RGB magnitudes, providing photometric data for a sample of 1346 bright stars, has been recently published, its usefulness is still limited due to the small number of reference stars available, considering that they are distributed throughout the whole celestial sphere, and the fact that they are restricted to John…
How stars formed in warps settle into (and contaminate) thick discs
Debattista, Victor P.; Beraldo e Silva, Leandro; Khachaturyants, Tigran
In recent years star formation has been discovered in the Milky Way's warp. These stars formed in the warp (warp stars) must eventually settle into the plane of the disc. We use an N-body+smooth particle hydrodynamics model of a warped galaxy to study how warp stars settle into the disc. By following warp stars in angular momentum space, we show t…
Exploring the dust content of galactic haloes with Herschel - IV. NGC 3079
Sturm, E.; Veilleux, S.; Rupke, D. S. N. +11 more
We present the results from an analysis of deep Herschel far-infrared (far-IR) observations of the edge-on disc galaxy NGC 3079. The point spread function-cleaned Photodetector Array Camera and Spectrometer (PACS) images at 100 and 160 µm display a 25 × 25 kpc2 X-shape structure centred on the nucleus that is similar in extent and orien…