Search Publications
Pathways to quiescence: SHARDS view on the star formation histories of massive quiescent galaxies at 1.0 < z < 1.5
Barro, Guillermo; Pérez-González, Pablo G.; Koekemoer, Anton M. +12 more
We present star formation histories (SFHs) for a sample of 104 massive (stellar mass M > 1010 M⊙) quiescent galaxies (MQGs) at z = 1.0-1.5 from the analysis of spectrophotometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) and HST/WFC3 G102 and G141 surveys of the GOODS-North field, jointly wit…
Is the escape velocity in star clusters linked to extended star formation histories? Using NGC 7252: W3 as a test case
Rejkuba, M.; Cabrera-Ziri, I.; Bastian, N. +9 more
The colour-magnitude diagrams of some intermediate-age (1-2 Gyr) star clusters show unexpectedly broad main-sequence turnoffs, raising the possibility that these clusters have experienced more than one episode of star formation. Such a scenario predicts the existence of an extended main-sequence turnoff (eMSTO) only in clusters with escape velocit…
Ultraviolet diversity of Type Ia Supernovae
Fox, O. D.; Kirshner, R. P.; Foley, Ryan J. +9 more
Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blu…
Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE
Zejda, M.; Skarka, M.; Liška, J. +2 more
This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS data base, and determined maxima timings from data of sky surveys and our own observations. T…
Towards a comprehensive picture of powerful quasars, their host galaxies and quasar winds at z ∼ 0.5
Zakamska, Nadia L.; Wylezalek, Dominika; Obied, Georges +1 more
Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured quasars where high-velocity-ionized nebulae have been found. We present rest-frame yellow-band (∼5000 Å) obse…
A lucky imaging multiplicity study of exoplanet host stars - II
Avenhaus, H.; Ginski, C.; Mugrauer, M. +6 more
The vast majority of extrasolar planets are detected by indirect detection methods such as transit monitoring and radial velocity measurements. While these methods are very successful in detecting short-periodic planets, they are mostly blind to wide sub-stellar or even stellar companions on long orbits. In our study, we present high-resolution im…
Chemical abundances in the multiple sub-giant branch of 47 Tucanae: insights on its faint sub-giant branch component
Milone, A. P.; Marino, A. F.; Bedin, L. R. +8 more
The globular cluster 47 Tuc exhibits a complex sub-giant branch (SGB) with a faint-SGB comprising only about the 10 per cent of the cluster mass and a bright-SGB hosting at least two distinct populations. We present a spectroscopic analysis of 62 SGB stars including 21 faint-SGB stars. We thus provide the first chemical analysis of the intriguing …
The 80 Ms follow-up of the X-ray afterglow of GRB 130427A challenges the standard forward shock model
Troja, E.; Piro, L.; Page, M. J. +12 more
GRB 130427A was the brightest gamma-ray burst detected in the last 30 yr. With an equivalent isotropic energy output of 8.5 × 1053 erg and redshift z = 0.34, it uniquely combined very high energetics with a relative proximity to Earth. As a consequence, its X-ray afterglow has been detected by sensitive X-ray observatories such as XMM-N…
Monsters in the dark: predictions for luminous galaxies in the early Universe from the BLUETIDES simulation
Wilkins, Stephen M.; Nagai, Daisuke; Croft, Rupert +3 more
Using deep Hubble and Spitzer observations Oesch et al. have identified a bright (MUV ≈ -22) star-forming galaxy candidate at z ≈ 11. The presence of GN-z11 implies a number density ∼10-6 Mpc-3, roughly an order of magnitude higher than the expected value based on extrapolations from lower redshift. Using the unpre…
Overconfidence in photometric redshift estimation
Wittman, David; Bhaskar, Ramya; Tobin, Ryan
We describe a new test of photometric redshift performance given a spectroscopic redshift sample. This test complements the traditional comparison of redshift differences by testing whether the probability density functions p(z) have the correct width. We test two photometric redshift codes, BPZ and EAZY, on each of two data sets and find that BPZ…