Search Publications
Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441
van der Marel, Roeland P.; Neumayer, Nadine; Watkins, Laura L. +6 more
We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a te…
Upper limits on the escape fraction of ionizing radiation from galaxies at 2 ≲ z < 6
Ryan-Weber, E. V.; Rafelski, M.; Bassett, R. +3 more
In this work, we investigate upper limits on the global escape fraction of ionizing photons ($f_{\rm esc/global}^{\rm abs}$) from a sample of galaxies probed for Lyman-continuum (LyC) emission characterized as non-LyC and LyC leakers. We present a sample of nine clean non-contaminated (by low-redshift interlopers, CCD problems, and internal reflec…
WISDOM project - VIII. Multiscale feedback cycles in the brightest cluster galaxy NGC 0708
Williams, Thomas G.; Sarzi, Marc; Cappellari, Michele +8 more
We present high-resolution (synthesized beam size 0${_{.}^{\prime\prime}}$088 × 0${_{.}^{\prime\prime}}$083 or 25 × 23 pc2) Atacama Large Millimetre/submillimetre Array 12CO(2-1) line and 236 GHz continuum observations, as well as 5 GHz enhanced Multi-Element Radio Linked Interferometer Network (e-MERLIN) continuum observatio…
In search of radio emission from exoplanets: GMRT observations of the binary system HD 41004
Henning, Thomas; Mathew, Blesson; Manoj, P. +6 more
This paper reports Giant Metrewave Radio Telescope (GMRT) observations of the binary system HD 41004 that are among the deepest images ever obtained at 150 and 400 MHz in the search for radio emission from exoplanets. The HD 41004 binary system consists of a K1 V primary star and an M2 V secondary; both stars are host to a massive planet or brown …
The outburst of a 60 min AM CVn reveals peculiar colour evolution: implications for outbursts in long-period double white dwarfs
Maccarone, T. J.; Cavecchi, Y.; Rivera Sandoval, L. E. +2 more
We report on multiwavelength observations during quiescence and of the first detected outburst of the ≈60 min orbital period AM CVn SDSS J113732+405458. Using X-ray and UV observations, we determined an upper limit duration of the event of about 1 yr. The amplitude of the outburst was remarkably small, of around 1 mag in r and 0.5 mag in g. We hav…
Identification of Sagittarius stream members in angular momentum space with gaussian mixture techniques
Peñarrubia, Jorge; Petersen, Michael S.
This paper uses Gaussian mixture techniques to dissect the Milky Way (MW) stellar halo in angular momentum space. Application to a catalogue of 5389 stars near the plane of the Sagittarius (Sgr) stream with full 6D phase-space coordinates supplied by Gaia EDR3 and SEGUE returns four independent dynamical components. The broadest and most populated…
The nearby extreme accretion and feedback system PDS 456: finding a complex radio-emitting nucleus
Nardini, Emanuele; Paragi, Zsolt; Varenius, Eskil +5 more
When a black hole accretes close to the Eddington limit, the astrophysical jet is often accompanied by radiatively driven, wide-aperture and mildly relativistic winds. Powerful winds can produce significant non-thermal radio emission via shocks. Among the nearby critical accretion quasars, PDS 456 has a very massive black hole (about 1 billion sol…
The size and pervasiveness of Ly α-UV spatial offsets in star-forming galaxies at z ∼ 6
Ryan, R. E.; Alvarez, C.; Hoag, A. +21 more
We study the projected spatial offset between the ultraviolet continuum and Ly α emission for 65 lensed and unlensed galaxies in the Epoch of Reionization (5 ≤ z ≤ 7), the first such study at these redshifts, in order to understand the potential for these offsets to confuse estimates of the Ly α properties of galaxies observed in slit spectroscopy…
Optical photometry of two transitional millisecond pulsars in the radio pulsar state
Dhillon, V. S.; Marsh, T. R.; Clark, C. J. +7 more
We present ULTRACAM multiband optical photometry of two transitional millisecond pulsars (tMSPs), PSR J1023+0038 and PSR J1227-4853, taken while both were in their radio pulsar states. The light curves show significant asymmetry about the flux maxima in all observed bands, suggesting an asymmetric source of heating in the system. We model the ligh…
Kinematics and multiband period-luminosity-metallicity relation of RR Lyrae stars via statistical parallax
Dambis, A. K.; Berdnikov, L. N.; Grebel, E. K. +2 more
This paper presents results from photometric and statistical-parallax analysis of a sample of 850 field RR Lyrae (RRL) variables. The photometric and spectroscopic data for our sample of RRLs are obtained from (1) our new spectroscopic observations (for 448 RRLs) carried out with the Southern African Large Telescope; (2) our photometric observatio…