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NuSTAR, XMM-Newton, and Suzaku Observations of the Ultraluminous X-Ray Source Holmberg II X-1
Harrison, F. A.; Stern, D.; Fabian, A. C. +14 more
We present the first broadband 0.3-25.0 keV X-ray observations of the bright ultraluminous X-ray source (ULX) Holmberg II X-1, performed by NuSTAR, XMM-Newton, and Suzaku in 2013 September. The NuSTAR data provide the first observations of Holmberg II X-1 above 10 keV and reveal a very steep high-energy spectrum, similar to other ULXs observed by …
Spectroscopic Study of Star-forming Galaxies in Filaments and the Field at z ~ 0.5: Evidence for Environmental Dependence of Electron Density
Sobral, David; Shivaei, Irene; Mobasher, Bahram +3 more
We study the physical properties of a spectroscopic sample of 28 star-forming galaxies in a large filamentary structure in the COSMOS field at z ∼ 0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of 30 field galaxies. We spectroscopically confirm the presence of a large galaxy filament (…
500 days of SN 2013dy: spectra and photometry from the ultraviolet to the infrared
Fox, O. D.; Lee, W. H.; Zheng, W. +23 more
SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to ∼ 500 d after explosion. We present 10 epochs of ultraviolet (UV) through near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), …
The progenitors of the Milky Way stellar halo: big bricks favoured over little bricks.
Belokurov, V.; Deason, A. J.; Weisz, D. R.
We present a census of blue horizontal branch (BHB) and blue straggler (BS) stars belonging to dwarf galaxies and globular clusters, and compare these counts to that of the Milky Way stellar halo. We find, in agreement with earlier studies, that the ratio of BS-to-BHB stars in these satellite populations is dependent on stellar mass. Dwarf galaxie…
Elemental Depletions in the Magellanic Clouds and the Evolution of Depletions with Metallicity
Meixner, Margaret; Seale, Jonathan; Dwek, Eli +4 more
We present a study of the composition of gas and dust in the Large and Small Magellanic Clouds (LMC and SMC) using UV absorption spectroscopy. We measure P ii and Fe ii along 84 spatially distributed sightlines toward the MCs using archival Far Ultraviolet Spectroscopic Explorer observations. For 16 of those sightlines, we also measure Si ii, Cr i…
The VLT SINFONI Mg II Program for Line Emitters (SIMPLE). II. Background Quasars Probing Z ~ 1 Galactic Winds
Finley, Hayley; Bouché, Nicolas; Contini, Thierry +3 more
The physical properties of galactic winds are of paramount importance for our understanding of galaxy formation. Fortunately, they can be constrained using background quasars passing near star-forming galaxies (SFGs). From the 14 quasar-galaxy pairs in our Very Large Telescope (VLT)/SINFONI Mg ii Program for Line Emitters sample, we reobserved the…
A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: HIPPARCOS-Tycho cool stars
Rosen, S.; Pye, J. P.; Schröder, A. C. +1 more
Context. The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection.
Aims: We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products pr…
The radio relic in Abell 2256: overall spectrum and implications for electron acceleration
Lovisari, L.; Dallacasa, D.; Bonafede, A. +5 more
Context. Radio relics are extended synchrotron sources thought to be produced by shocks in the outskirts of merging galaxy clusters. The cluster Abell 2256 hosts one of the most intriguing examples in this class of sources. It has been found that this radio relic has a rather flat integrated spectrum at low frequencies that would imply an injectio…
New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue
Parker, Quentin A.; Vickers, Shane B.; Frew, David J. +1 more
We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Toruń catalogue of Szczerba et al., and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are es…
Spectroscopic Confirmation of an Ultra Massive and Compact Galaxy at z = 3.35: a Detailed Look at an Early Progenitor of Local Giant Ellipticals
van Dokkum, Pieter G.; Muzzin, Adam; Labbé, Ivo +10 more
We present the first spectroscopic confirmation of an ultramassive galaxy at redshift z\gt 3 using data from Keck-NIRSPEC, VLT-X-shooter, and GTC-Osiris. We detect strong [O iii] and Lyα emission, and weak [O ii], C iv, and He ii, placing C1-23152 at a spectroscopic redshift of {{z}spec}=3.351. The modeling of the emission-line-correcte…