Search Publications
The origin of X-ray emission in the gamma-ray emitting narrow-line Seyfert 1 1H 0323+342
Fabian, A. C.; Reynolds, C. S.; Pinto, C. +7 more
We present the results of X-ray spectral and timing analyses of the closest gamma-ray emitting narrow-line Seyfert 1 (γ-NLS1) galaxy, 1H 0323+342. We use observations from a recent, simultaneous XMM-Newton/NuSTAR campaign. As in radio-quiet NLS1s, the spectrum reveals a soft excess at low energies (≲2 keV) and reflection features such as a broad i…
Explaining the chemical trajectories of accreted and in-situ halo stars of the Milky Way
Gibson, Brad K.; Kawata, Daisuke; Gallart, Carme +2 more
The Milky Way underwent its last significant merger ten billion years ago, when the Gaia-Enceladus-Sausage (GES) was accreted. Accreted GES stars and progenitor stars born prior to the merger make up the bulk of the inner halo. Even though these two main populations of halo stars have similar durations of star formation prior to their merger, they…
The H α star formation main sequence in cluster and field galaxies at z ∼ 1.6
Cooper, M. C.; Muzzin, Adam; Forrest, Ben +16 more
We calculate H α-based star formation rates and determine the star formation rate-stellar mass relation for members of three Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) clusters at z ~ 1.6 and serendipitously identified field galaxies at similar redshifts to the clusters. We find similar star formation rates in cluster and field…
The Gaia Ultra-Cool Dwarf Sample - III: seven new multiple systems containing at least one Gaia DR2 ultracool dwarf.
Caballero, J. A.; Sarro, L. M.; Marocco, F. +8 more
We present 10 new ultracool dwarfs in seven wide binary systems discovered using Gaia second data release data, identified as part of our Gaia Ultra-Cool Dwarf Sample project. The seven systems presented here include an L1 companion to the G5 IV star HD 164507, an L1: companion to the V478 Lyr AB system, an L2 companion to the metal-poor K5 V star…
The mergers in Abell 2256: displaced gas and its connection to the radio-emitting plasma
Simionescu, A.; Mernier, F.; Werner, N. +5 more
We present the results of deep Chandra and XMM-Newton X-ray imaging and spatially resolved spectroscopy of Abell 2256, a nearby (z = 0.058) galaxy cluster experiencing multiple mergers and displaying a rich radio morphology dominated by a large relic. The X-ray data reveal three subclusters: (I) the 'main cluster'; (II) the remnant of an older mer…
Masses of the components of SB2 binaries observed with Gaia - V. Accurate SB2 orbits for 10 binaries and masses of the components of 5 binaries
Mazeh, T.; Halbwachs, J. -L.; Arenou, F. +8 more
Double-lined spectroscopic binaries (SB2s) are one of the main sources of stellar masses, as additional observations are only needed to give the inclinations of the orbital planes in order to obtain the individual masses of the components. For this reason, we are observing a selection of SB2s using the SOPHIE spectrograph at the Haute-Provence obs…
Leveraging HST with MUSE - I. Sodium abundance variations within the 2-Gyr-old cluster NGC 1978
Martocchia, S.; Salaris, M.; Dreizler, S. +10 more
Nearly all of the well-studied ancient globular clusters (GCs), in the Milky Way and in nearby galaxies, show star-to-star variations in specific elements (e.g. He, C, N, O, Na, and Al), known as 'multiple populations' (MPs). However, MPs are not restricted to ancient clusters, with massive clusters down to ~2 Gyr showing signs of chemical variati…
Overdensity of SMGs in fields containing z ∼ 0.3 galaxies: magnification bias and the implications for studies of galaxy evolution
Bonavera, L.; Dunne, L.; Maddox, S. J. +2 more
We report a remarkable overdensity of high-redshift submillimetre galaxies (SMG), 4-7 times the background, around a statistically complete sample of twelve 250 µm selected galaxies at z = 0.35, which were targeted by ALMA in a study of gas tracers. This overdensity is consistent with the effect of lensing by the haloes hosting the target z …
Thermal inertias of pebble-pile comet 67P/Churyumov-Gerasimenko
Ohno, Kazumasa; Arakawa, Sota
The Rosetta mission to comet 67P/Churyumov-Gerasimenko has provided new data to better understand what comets are made of. The weak tensile strength of the cometary surface materials suggests that the comet is a hierarchical dust aggregate formed through gravitational collapse of a bound clump of small dust aggregates so-called 'pebbles' in the ga…
When the disc's away, the stars will play: dynamical masses in the nova-like variable KR Aur with a pinch of accretion
Gänsicke, B. T.; Koester, D.; Toloza, O. +8 more
We obtained time-resolved optical photometry and spectroscopy of the nova-like variable KR Aurigae in the low state. The spectrum reveals a DAB white dwarf (WD) and a mid-M dwarf companion. Using the companion star's i-band ellipsoidal modulation we refine the binary orbital period to be P = 3.906519 ± 0.000001 h. The light curve and the spectra s…