Search Publications
SU Lyncis, a hard X-ray bright M giant: clues point to a large hidden population of symbiotic stars
Nuñez, N. E.; Nelson, T.; Mukai, K. +6 more
Symbiotic star surveys have traditionally relied almost exclusively on low resolution optical spectroscopy. However, we can obtain a more reliable estimate of their total Galactic population by using all available signatures of the symbiotic phenomenon. Here we report the discovery of a hard X-ray source, 4PBC J0642.9+5528, in the Swift hard X-ray…
Timing the warm absorber in NGC 4051
Costantini, E.; Uttley, P.; Silva, C. V.
We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results of the extensive 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051 whose spectrum has revealed a complex multicomponent…
Evidence for the thermal Sunyaev-Zel'dovich effect associated with quasar feedback
Hilton, Matt; Sifón, Cristóbal; Bond, J. Richard +20 more
Using a radio-quiet subsample of the Sloan Digital Sky Survey spectroscopic quasar catalogue, spanning redshifts 0.5-3.5, we derive the mean millimetre and far-infrared quasar spectral energy distributions (SEDs) via a stacking analysis of Atacama Cosmology Telescope and Herschel-Spectral and Photometric Imaging REceiver data. We constrain the for…
Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz. A kpc-scale star forming disk surrounding nuclei with shocked outflows
Beswick, R.; Gallagher, J. S.; Horellou, C. +16 more
Context. Arp 220 is the prototypical ultra luminous infrared galaxy (ULIRG). Despite extensive studies, the structure at MHz-frequencies has remained unknown because of limits in spatial resolution.
Aims: This work aims to constrain the flux and shape of radio emission from Arp 220 at MHz frequencies.
Methods: We analyse new observations…
Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere
Smith, Howard A.; Masetti, N.; Jiménez-Bailón, E. +12 more
The extragalactic γ-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei. Many of the γ-ray sources included in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs) because there are no optical spectra available in the literature to confirm thei…
Primordial features and Planck polarization
Starobinsky, Alexei A.; Hazra, Dhiraj Kumar; Smoot, George F. +1 more
With the Planck 2015 Cosmic Microwave Background (CMB) temperature and polarization data, we search for possible features in the primordial power spectrum (PPS). We revisit the Wiggly Whipped Inflation (WWI) framework and demonstrate how generation of some particular primordial features can improve the fit to Planck data. WWI potential allows the …
The magnetic field and dust filaments in the Polaris Flare
Panopoulou, G. V.; Tassis, K.; Psaradaki, I.
In diffuse molecular clouds, possible precursors of star-forming clouds, the effect of the magnetic field is unclear. In this work, we compare the orientations of filamentary structures in the Polaris Flare, as seen through dust emission by Herschel, to the plane-of-the-sky magnetic field orientation (Bpos) as revealed by stellar optica…
Large-scale Structure around a z=2.1 Cluster
Casey, Caitlin M.; Kacprzak, Glenn G.; Tran, Kim-Vy H. +10 more
The most prodigious starburst galaxies are absent in massive galaxy clusters today, but their connection with large-scale environments is less clear at z≳ 2. We present a search of large-scale structure around a galaxy cluster core at z = 2.095 using a set of spectroscopically confirmed galaxies. We find that both color-selected star-forming galax…
Plasma code for astrophysical charge exchange emission at X-ray wavelengths
Raassen, A. J. J.; Gu, Liyi; Kaastra, Jelle
Charge exchange X-ray emission provides unique insight into the interactions between cold and hot astrophysical plasmas. Besides its own profound science, this emission is also technically crucial to all observations in the X-ray band, since charge exchange with the solar wind often contributes a significant foreground component that contaminates …
The JCMT Gould Belt Survey: Evidence for Dust Grain Evolution in Perseus Star-forming Clumps
White, G. J.; Di Francesco, J.; Marsh, K. +56 more
The dust emissivity spectral index, β, is a critical parameter for deriving the mass and temperature of star-forming structures and, consequently, their gravitational stability. The β value is dependent on various dust grain properties, such as size, porosity, and surface composition, and is expected to vary as dust grains evolve. Here we present …