Search Publications
Nine tiny star clusters in Gaia DR1, PS1, and DES
Belokurov, V.; Koposov, S. E.; Torrealba, G.
We present the results of a systematic Milky Way satellite search performed across an array of publicly available wide-area photometric surveys. Our aim is to complement previous searches by widening the parameter space covered. Specifically, we focus on objects smaller than 1 arcmin and include old, young, metal-poor, and metal-rich stellar popul…
Nature versus nurture: what regulates star formation in satellite galaxies?
Hirschmann, Michaela; De Lucia, Gabriella; Fontanot, Fabio
We use our state-of-the-art Galaxy Evolution and Assembly (GAEA) semi-analytic model to study how and on which time-scales star formation is suppressed in satellite galaxies. Our fiducial stellar feedback model, implementing strong stellar driven outflows, reproduces relatively well the variations of passive fractions as a function of galaxy stell…
The velocity anisotropy of the Milky Way satellite system
Grand, Robert J. J.; Gómez, Facundo A.; Fattahi, Azadeh +9 more
We analyse the orbital kinematics of the Milky Way (MW) satellite system utilizing the latest systemic proper motions for 38 satellites based on data from Gaia Data Release 2. Combining these data with distance and line-of-sight velocity measurements from the literature, we use a likelihood method to model the velocity anisotropy, β, as a function…
Galactic rotation from Cepheids with Gaia DR2 and effects of non-axisymmetry
Bovy, Jo; Matsunaga, Noriyuki; Kawata, Daisuke +1 more
We apply a simple axisymmetric disc model to 218 Galactic Cepheids whose accurate measurements of the distance and velocities are obtained by cross-matching an existing Cepheids catalogue with the Gaia DR2 data. Our model fit determines the `local centrifugal speed', Vc - defined as the rotation speed required to balance the local radia…
H0LiCOW - X. Spectroscopic/imaging survey and galaxy-group identification around the strong gravitational lens system WFI 2033-4723
Smith, M.; Annis, J.; Bertin, E. +65 more
Galaxies and galaxy groups located along the line of sight towards gravitationally lensed quasars produce high-order perturbations of the gravitational potential at the lens position. When these perturbation are too large, they can induce a systematic error on H0 of a few per cent if the lens system is used for cosmological inference an…
Discrepancies in the ages of young star clusters; evidence for mergers?
Smith, Nathan; Bastian, Nate; Beasor, Emma R. +1 more
There is growing evidence that star clusters can no longer be considered simple stellar populations. Intermediate- and old-age clusters are often found to have extended main-sequence turn-offs (eMSTOs) which are difficult to explain with single-age isochrones, an effect attributed to rotation. In this paper, we provide the first characterization o…
X-ray dips and a complex UV/X-ray cross-correlation function in the black hole candidate MAXI J1820+070
Sanna, A.; Motta, S. E.; Segreto, A. +3 more
MAXI J1820+070, a black hole candidate first detected in early 2018 March, was observed by XMM-Newton during the outburst rise. In this letter we report on the spectral and timing analysis of the XMM-Newton X-ray and UV data, as well as contemporaneous X-ray data from the Swift satellite. The X-ray spectrum is well described by a hard thermal Comp…
Discovery of disc truncations above the galaxies' mid-plane in Milky Way-like galaxies
Trujillo, Ignacio; Knapen, Johan H.; Martínez-Lombilla, Cristina
Disc truncations are the closest feature to an edge that galaxies have, but the nature of this phenomenon is not yet understood. In this paper we explore the truncations in two nearby (D ∼15 Mpc) Milky Way-like galaxies: NGC 4565 and NGC 5907. We cover a wide wavelength range from the NUV and optical to 3.6 {µ m}. We find that the radius of …
WISDOM project - IV. A molecular gas dynamical measurement of the supermassive black hole mass in NGC 524
Sarzi, Marc; Cappellari, Michele; Davis, Timothy A. +6 more
We present high angular resolution (0.3 arcsec or 37 pc) Atacama Large Millimeter/submillimeter Array observations of the CO(2-1) line emission from a central disc in the early-type galaxy NGC 524. This disc is shown to be dynamically relaxed, exhibiting ordered rotation about a compact 1.3 mm continuum source, which we identify as emission from a…
Detection of a giant flare displaying quasi-periodic pulsations from a pre-main-sequence M star by the Next Generation Transit Survey
Jackman, James A. G.; Wheatley, Peter J.; Raddi, Roberto +18 more
We present the detection of an energetic flare on the pre-main-sequence M3 star NGTS J121939.5-355557, which we estimate to be only 2 Myr old. The flare had an energy of 3.2± ^{0.4}_{0.3}× 10^{36} erg and a fractional amplitude of 7.2 ± 0.8, making it one of the most energetic flares seen on an M star. The star is also X-ray active, in the saturat…