Search Publications
Evidence for crater ejecta on Venus tessera terrain from Earth-based radar images
Campbell, Donald B.; Nolan, Michael C.; Campbell, Bruce A. +3 more
We combine Earth-based radar maps of Venus from the 1988 and 2012 inferior conjunctions, which had similar viewing geometries. Processing of both datasets with better image focusing and co-registration techniques, and summing over multiple looks, yields maps with 1-2 km spatial resolution and improved signal to noise ratio, especially in the weake…
The Chandra Local Volume Survey. I. The X-Ray Point Source Populations of NGC 55, NGC 2403, and NGC 4214
Dalcanton, J. J.; Skillman, E. D.; Kong, A. K. H. +7 more
We present comprehensive X-ray point source catalogs of NGC 55, NGC 2403, and NGC 4214 as part of the Chandra Local Volume Survey. The combined archival observations have effective exposure times of 56.5 ks, 190 ks, and 79 ks for NGC 55, NGC 2403, and NGC 4214, respectively. When combined with our published catalogs for NGC 300 and NGC 404, our su…
Radio relics tracing the projected mass distribution in CIZA J2242.8+5301*
Umetsu, Keiichi; Fujita, Yutaka; Okabe, Nobuhiro +4 more
We present a weak-lensing analysis for a merging galaxy cluster, CIZA J2242.8+5301, which hosts double radio relics, using three-band Subaru/Suprime-Cam imaging (Br'z'). Since the lifetime of dark matter halos colliding into clusters is longer than that of X-ray emitting gas halos, weak-lensing analysis is a powerful method t…
The changing UV and X-ray properties of the Of?p star CPD -28°2561
Wade, Gregg A.; Walborn, Nolan R.; Nazé, Yaël +4 more
The Of?p star CPD -28°2561 was monitored at high energies with XMM-Newton and HST. In X-rays, this magnetic oblique rotator displays bright and hard emission that varies by ∼55 per cent with rotational phase. These changes occur in phase with optical variations, as expected for magnetically confined winds; there are two maxima and two minima in X-…
When is pile-up important in the XMM-Newton EPIC cameras?
Guainazzi, M.; Rodriguez-Pascual, P.; Stuhlinger, M. +2 more
Context. Pile-up in X-ray charged couple device (CCD) detectors is defined as the reconstruction of independent events in the same detection cell as a single event during a read-out cycle. Pile-up can seriously compromise the spectral performance, modifying both the flux and the spectral shape of celestial sources.
Aims: In this paper we defi…
The Gaia spectrophotometric standard stars survey: II. Instrumental effects of six ground-based observing campaigns
Jordi, C.; Figueras, F.; Marinoni, S. +16 more
The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, was awarded almost 450 observing nights and accumulated almost 100 000 raw data frames with both photometric and spectroscopic observations. Such large observational effort requires careful, homogeneous, and automatic data reduction and quality control procedures. In this pa…
A variable-density absorption event in NGC 3227 mapped with Suzaku and Swift
Guainazzi, M.; Elvis, M.; Miniutti, G. +15 more
Context. The morphology of the circumnuclear gas accreting onto supermassive black holes in Seyfert galaxies remains a topic of much debate. As the innermost regions of active galactic nuclei (AGN) are spatially unresolved, X-ray spectroscopy, and in particular line-of-sight absorption variability, is a key diagnostic to map out the distribution o…
Testing Dark Matter Halo Models of Quasars with Thermal Sunyaev-Zeldovich Effect
Cen, Renyue; Safarzadeh, Mohammadtaher
A statistical analysis of stacked Compton-y maps of quasar hosts with a median redshift of 1.5 using Millennium Simulation is performed to address two issues: one on the feedback energy from quasars and the other on testing dark matter halo models for quasar hosts. On the first, we find that at the resolution of FWHM = 10 arcmin obtained by Planck…
When do stars in 47 Tucanae lose their mass?
Marigo, Paola; Richer, Harvey B.; Heyl, Jeremy +4 more
By examining the diffusion of young white dwarfs through the core of the globular cluster 47 Tucanae, we estimate the time when the progenitor star lost the bulk of its mass to become a white dwarf. According to stellar evolution models of the white-dwarf progenitors in 47 Tucanae, we find this epoch to coincide approximately with the star ascendi…
The evolution of galaxy star formation activity in massive haloes
Finoguenov, A.; Berta, S.; Magnelli, B. +20 more
Context. There is now a large consensus that the current epoch of the cosmic star formation history (CSFH) is dominated by low mass galaxies while the most active phase, between redshifts 1 and 2, is dominated by more massive galaxies, which evolve more quickly.
Aims: Massive galaxies tend to inhabit very massive haloes, such as galaxy groups…