Search Publications
Calibration of colour gradient bias in shear measurement using HST/CANDELS data
Schrabback, T.; Hoekstra, H.; Maoli, R. +6 more
Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity for a broad-band observation can lead to new subtle effects that could hitherto be ignored…
Radio/X-ray monitoring of the broad-line radio galaxy 3C 382. High-energy view with XMM-Newton and NuSTAR
Bianchi, S.; Cappi, M.; Ponti, G. +14 more
We present the analysis of five joint XMM-Newton/NuSTAR observations, 20 ks each and separated by 12 days, of the broad-line radio galaxy 3C 382. The data were obtained as part of a campaign performed in September-October 2016 simultaneously with Very Long Baseline Array. The radio data and their relation with the X-ray ones will be discussed in a…
Testing the white dwarf mass-radius relation and comparing optical and far-UV spectroscopic results with Gaia DR2, HST, and FUSE
Barstow, M. A.; Holberg, J. B.; Casewell, S. L. +3 more
Observational tests of the white dwarf mass-radius relationship have always been limited by the uncertainty in the available distance measurements. Most studies have focused on Balmer line spectroscopy because these spectra can be obtained from ground-based observatories, while the Lyman lines are only accessible to space-based UV telescopes. We p…
SMHASH: anatomy of the Orphan Stream using RR Lyrae stars
Law, David R.; Kollmeier, Juna A.; van der Marel, Roeland P. +29 more
Stellar tidal streams provide an opportunity to study the motion and structure of the disrupting galaxy as well as the gravitational potential of its host. Streams around the Milky Way are especially promising as phase space positions of individual stars will be measured by ongoing or upcoming surveys. Nevertheless, it remains a challenge to accur…
The connection between the peaks in velocity dispersion and star-forming clumps of turbulent galaxies
Fisher, D. B.; Glazebrook, K.; Obreschkow, D. +5 more
We present Keck/OSIRIS adaptive optics observations with 150-400 pc spatial sampling of 7 turbulent, clumpy disc galaxies from the DYNAMO sample ($0.07<z<0.2$). DYNAMO galaxies have previously been shown to be well matched in properties to main sequence galaxies at $z\sim1.5$. Integral field spectroscopy observations using adaptive optics ar…
The Kormendy relation of galaxies in the Frontier Fields clusters: Abell S1063 and MACS J1149.5+2223
Tortorelli, Luca; Annunziatella, Marianna; Lombardi, Marco +12 more
We analyse the Kormendy relations (KRs) of the two Frontier Fields clusters, Abell S1063, at z = 0.348, and MACS J1149.5+2223, at z = 0.542, exploiting very deep Hubble Space Telescope photometry and Very Large Telescope (VLT)/Multi Unit Spectroscopic Explorer (MUSE) integral field spectroscopy. With this novel data set, we are able to investigate…
Pulsations and eclipse-time analysis of HW Vir
Dhillon, V. S.; Marsh, T. R.; Reed, M. D. +9 more
We analysed recent K2 data of the short-period eclipsing binary system HW Vir, which consists of a hot subdwarf-B type primary with an M-dwarf companion. We determined the mid-times of eclipses, calculated O-C diagrams, and an average shift of the secondary minimum. Our results show that the orbital period is stable within the errors over the cour…
Gaia transients in galactic nuclei
Harrison, D. L.; Koposov, S. E.; van Leeuwen, F. +9 more
The high spatial resolution and precise astrometry and photometry of the Gaia mission should make it particularly apt at discovering and resolving transients occurring in, or near, the centres of galaxies. Indeed, some nuclear transients are reported by the Gaia Science Alerts (GSA) team, but not a single confirmed tidal disruption event (TDE) has…
K2-139 b: a low-mass warm Jupiter on a 29-d orbit transiting an active K0 V star
Erikson, A.; Pätzold, M.; Rauer, H. +27 more
We announce the discovery of K2-139 b (EPIC 218916923 b), a transiting warm-Jupiter (Teq = 547 ± 25 K) on a 29-d orbit around an active (log R^' _HK = -4.46 ± 0.06) K0 V star in K2 Campaign 7. We derive the system's parameters by combining the K2 photometry with ground-based follow-up observations. With a mass of 0.387 _{ - 0.075 } ^ {+…
Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium
Kramer, M.; Pilia, M.; Grießmeier, J. -M. +17 more
We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 yr at 150 MHz using the LOw Frequency ARray (LOFAR), but they are not seen in contemporaneous Lovell observations at 1.5 GHz. We argue that prop…