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Finding r-II Sibling Stars in the Milky Way with the Greedy Optimistic Clustering Algorithm
Hattori, Kohei; Roederer, Ian U.; Okuno, Akifumi
R-process enhanced stars with [Eu/Fe] ≥ +0.7 (so-called r-II stars) are believed to have formed in an extremely neutron-rich environment in which a rare astrophysical event (e.g., a neutron-star merger) occurred. This scenario is supported by the existence of an ultra-faint dwarf galaxy, Reticulum II, where most of the stars are highly enhanced in…
Target-of-Opportunity Observation Detectability of Kilonovae with WFST
Dai, Zi-Gao; Zhao, Wen; Liu, Zheng-Yan +4 more
Kilonovae are approximately thermal transients, produced by the mergers of binary neutron stars (BNSs) and neutron star (NS)-black hole binaries. As the optical counterpart of the gravitational-wave event GW170817, AT2017gfo is the first kilonova detected with smoking-gun evidence. Its observation offers vital information for constraining the Hubb…
Dynamics of stellar disc tilting from satellite mergers
Lisanti, Mariangela; Dodge, Benjamin C.; Slone, Oren +1 more
The Milky Way's stellar disc can tilt in response to torques that result from infalling satellite galaxies and their associated tidal debris. In this work, we explore the dynamics of disc tilting by running N-body simulations of mergers in an isolated, isotropic Milky Way-like host galaxy, varying over satellite virial mass, initial position, and …
The Gaia-ESO survey: Placing constraints on the origin of r-process elements
Guiglion, G.; Randich, S.; Bragaglia, A. +19 more
Context. A renewed interest in the origin of r-process elements has been stimulated by the multi-messenger observation of the gravitational event GW170817, with the detection of both gravitational waves and electromagnetic waves corresponding to the merger of two neutron stars. Such a phenomenon has been proposed as one of the main sources of the …
The effect of the adiabatic assumption on asteroseismic scaling relations for luminous red giants
Stello, Dennis; Pinsonneault, Marc H.; Bildsten, Lars +1 more
Although stellar radii from asteroseismic scaling relations agree at the per cent level with independent estimates for main sequence and most first-ascent red giant branch (RGB) stars, the scaling relations over-predict radii at the tens of per cent level for the most luminous stars ($R \gtrsim 30 \, \mathrm{R}_{\odot }$). These evolved stars have…
RXJ0437+00: constraining dark matter with exotic gravitational lenses
Mahler, Guillaume; Richard, Johan; Massey, Richard +6 more
We present the first strong-gravitational-lensing analysis of the galaxy cluster RX J0437.1+0043 (RXJ0437; z = 0.285). Newly obtained, deep MUSE observations, Keck/MOSFIRE near-infrared spectroscopy, and Hubble Space Telescope SNAPshot imaging reveal 13 multiply imaged background galaxies, three of them (at z = 1.98, 2.97, and 6.02, respectively) …
INTEGRAL study of MAXI J1535−571, MAXI J1820+070, and MAXI J1348 − 630 outbursts. I. Detection and polarization properties of the high-energy emission
Belloni, T.; Petrucci, P. -O.; Rodriguez, J. +5 more
In black hole X-ray binaries, a nonthermal high-energy component is sometimes detected at energies above 200 keV. The origin of this high-energy component is debated and distinct spectral modelizations can lead to different interpretations. High-energy polarimetry measurements with the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) ena…
The Physics of the Accelerating Universe Survey: narrow-band image photometry
Carretero, J.; Castander, F. J.; Crocce, M. +22 more
PAUCam is an innovative optical narrow-band imager mounted at the William Herschel Telescope built for the Physics of the Accelerating Universe Survey (PAUS). Its set of 40 filters results in images that are complex to calibrate, with specific instrumental signatures that cannot be processed with traditional data reduction techniques. In this pape…
Can ultralight dark matter explain the age-velocity dispersion relation of the Milky Way disc: A revised and improved treatment
Chiang, Barry T.; Ostriker, Jeremiah P.; Schive, Hsi-Yu
Ultralight axion-like particles ma ~ 10-22 eV, or Fuzzy Dark Matter (FDM), behave comparably to cold dark matter (CDM) on cosmological scales and exhibit a kpc-size de Broglie wavelength capable of alleviating established (sub-)galactic-scale problems of CDM. Substructures inside an FDM halo incur gravitational potential pert…
On the α/Fe Bimodality of the M31 Disks
Kobayashi, Chiaki; Gerhard, Ortwin; Arnaboldi, Magda +1 more
An outstanding question is whether the α/Fe bimodality exists in disk galaxies other than in the Milky Way. Here we present a bimodality using our state-of-the-art galactic chemical evolution models that can explain various observations in the Andromeda galaxy (M31) disks, namely, elemental abundances both of planetary nebulae and of red giant bra…