Search Publications
A new candidate pulsating ULX in NGC 7793
Bachetti, M.; Webb, N. A.; Fürst, F. +2 more
We report here the discovery of NGC 7793 ULX-4, a new transient ultraluminous X-ray source (ULX) in NGC 7793, a spiral galaxy already well known for harbouring several ULXs. This new source underwent an outburst in 2012, when it was detected by XMM-Newton and the Swift X-ray telescope. The outburst reached a peak luminosity of 3.4 × 1039
The Pristine Inner Galaxy Survey (PIGS) III: carbon-enhanced metal-poor stars in the bulge
Lewis, Geraint F.; Placco, Vinicius M.; Buder, Sven +15 more
The most metal-deficient stars hold important clues about the early buildup and chemical evolution of the Milky Way, and carbon-enhanced metal-poor (CEMP) stars are of special interest. However, little is known about CEMP stars in the Galactic bulge. In this paper, we use the large spectroscopic sample of metal-poor stars from the Pristine Inner G…
Faint LAEs near z > 4.7 C IV absorbers revealed by MUSE
Salvadori, S.; Ouchi, M.; Vanzella, E. +5 more
We present the results from the search for Lyman alpha emitters (LAEs) in the proximity of 11 C IV absorption systems at z > 4.7 in the spectrum of the QSO J1030+0524, using data from Multi-Unit Spectroscopic Explorer. We have found multiple LAE candidates close to four C IV systems at $z_{{\rm{C {\small IV}}}}=4.94$ -5.74 with $\log _{10}(N_{{…
Completeness of the Gaia-verse - IV. The astrometry spread function of Gaia DR2
Everall, Andrew; Boubert, Douglas; Koposov, Sergey E. +2 more
Gaia Data Release 2 (DR2) published positions, parallaxes, and proper motions for an unprecedented 1331 909 727 sources, revolutionizing the field of Galactic dynamics. We complement this data with the astrometry spread function (ASF), the expected uncertainty in the measured positions, proper motions, and parallax for a non-accelerating point sou…
X-ray binary accretion states in active galactic nuclei? Sensing the accretion disc of supermassive black holes with mid-infrared nebular lines
Fernández-Ontiveros, Juan A.; Muñoz-Darias, Teo
Accretion states, which are universally observed in stellar mass black holes in X-ray binaries, might be expected in active galactic nuclei (AGN). This is the case at low luminosities, when the jet-corona coupling dominates the energy output in both populations. Previous attempts to extend this framework to a wider AGN population have been extreme…
The impact of ionized outflows from z 2.5 quasars is not through instantaneous in situ quenching: the evidence from ALMA and VLT/SINFONI
Alexander, D. M.; Mullaney, J.; Mainieri, V. +7 more
We present high-resolution (~2.4 kpc) ALMA band 7 observations (rest-frame λ ~ 250 $\mu$m) of three powerful z ~ 2.5 quasars (Lbol = 1047.3-1047.5 erg s-1). These targets have previously been reported as showing evidence for suppressed star formation based on cavities in the narrow H α emission at the lo…
2D kinematics of massive stars near the Galactic Centre
Anderson, Jay; Bedin, Luigi R.; Sabbi, Elena +12 more
The presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A* …
Red noise and pulsations in evolved massive stars
Nazé, Yaël; Gosset, Eric; Rauw, Gregor
We examine high-cadence space photometry taken by the Transiting Exoplanet Survey Satellite (TESS) of a sample of evolved massive stars: 26 Wolf-Rayet stars (WRs) and eight luminous blue variables (LBVs) or candidate LBVs. To avoid confusion problems, only stars without bright Gaia neighbours and without evidence of bound companions are considered…
A high-rate foreground of sub-second flares from geosynchronous satellites
Ofek, Eran O.; Polishook, David; Nir, Guy +3 more
The Weizmann Fast Astronomical Survey Telescope is a 55 cm optical survey telescope with a high-cadence (25 Hz) monitoring of the sky over a wide field of view (≈7 deg2). The high frame rate allows detection of sub-second transients over multiple images. We present a sample of ~0.1-0.3 s duration flares detected in an untargeted survey …
A bottom-heavy initial mass function for the likely-accreted blue-halo stars of the Milky Way
Maoz, Dan; Hallakoun, Na'ama
We use Gaia DR2 to measure the initial mass function (IMF) of stars within 250 pc and masses in the range of 0.2 < m/M⊙ < 1.0, separated according to kinematics and metallicity, as determined from Gaia transverse velocity, vT, and location on the Hertzsprung-Russell diagram (HRD). The predominant thin-disc population (v…