Search Publications
NGC 1850 BH1 is another stripped-star binary masquerading as a black hole
El-Badry, Kareem; Burdge, Kevin B.
We show that the radial velocity variable star in the black hole (BH) candidate NGC 1850 BH1 cannot be a normal ${\approx}5\hbox{-}{\rm M}_{\odot }$ subgiant, as was proposed, but is an overluminous stripped-envelope star with mass ≈1 M⊙. The result follows directly from the star's observed radius and the orbital period-density relation…
Stellar mergers as the origin of the blue main-sequence band in young star clusters
Lennon, D. J.; Sana, Hugues; Castro, Norberto +10 more
Recent high-quality Hubble Space Telescope photometry shows that the main-sequence stars of young star clusters form two discrete components in the colour-magnitude diagram. On the basis of their distribution in the colour-magnitude diagram, we show that stars of the blue main-sequence component can be understood as slow rotators originating from …
Proton acceleration in thermonuclear nova explosions revealed by gamma rays
Maraschi, L.; Covino, S.; Antonelli, L. A. +207 more
Classical novae are cataclysmic binary star systems in which the matter of a companion star is accreted on a white dwarf1,2. Accumulation of hydrogen in a layer eventually causes a thermonuclear explosion on the surface of the white dwarf3, brightening the white dwarf to ~105 solar luminosities and triggering eject…
Irreducible Axion Background
Rodd, Nicholas L.; Langhoff, Kevin; Outmezguine, Nadav Joseph
Searches for dark matter decaying into photons constrain its lifetime to be many orders of magnitude larger than the age of the Universe. A corollary statement is that the abundance of any particle that can decay into photons over cosmological timescales is constrained to be much smaller than the cold dark-matter density. We show that an irreducib…
Exploring the physical properties of lensed star-forming clumps at 2 ≲ z ≲ 6
Zanella, A.; Castellano, M.; Grillo, C. +12 more
We study the physical properties (size, stellar mass, luminosity, and star formation rate) and scaling relations for a sample of 166 star-forming clumps with redshift z ~ 2-6.2. They are magnified by the Hubble Frontier Field galaxy cluster MACS J0416 and have robust lensing magnification (2 ≲ µ ≲ 82) computed by using our high-precision len…
Strong Lyman-α emission in an overdense region at z = 6.8: a very large (R 3 physical Mpc) ionized bubble in COSMOS?
Stark, Daniel P.; Endsley, Ryan
Our understanding of reionization has advanced considerably over the past decade, with several results now demonstrating that the intergalactic medium transitioned from substantially neutral at z = 7 to largely reionized at z = 6. However, little remains known about the sizes of ionized bubbles at z ≳ 7 as well as the galaxy overdensities which dr…
Space Weather Environment During the SpaceX Starlink Satellite Loss in February 2022
Millward, George; Singer, Howard J.; Fang, Tzu-Wei +7 more
On 3 February 2022, SpaceX Starlink launched and subsequently lost 38 of 49 satellites due to enhanced neutral density associated with a geomagnetic storm. This study examines the space weather conditions related to the satellite loss, based on observations, forecasts, and numerical simulations from the National Oceanic and Atmospheric Administrat…
MeerKAT view of the diffuse radio sources in Abell 3667 and their interactions with the thermal plasma
Finoguenov, A.; Brüggen, M.; de Gasperin, F. +11 more
Context. During their lifetimes, galaxy clusters grow through the accretion of matter from the filaments of the large-scale structure and from mergers with other clusters. These mergers release a large amount of energy into the intracluster medium (ICM) through merger shocks and turbulence. These phenomena are associated with the formation of radi…
CLASSY IV. Exploring UV Diagnostics of the Interstellar Medium in Local High-z Analogs at the Dawn of the JWST Era
Ravindranath, Swara; Martin, Crystal L.; Feltre, Anna +22 more
The Cosmic Origins Spectrograph (COS) Legacy Archive Spectroscopic SurveY (CLASSY) provides the first high-resolution spectral catalog of 45 local high-z analogs in the ultraviolet (UV; 1200-2000 Å) to investigate their stellar and gas properties. Here we present a toolkit of UV interstellar medium (ISM) diagnostics, analyzing the main emission li…
Astrometric identification of nearby binary stars - I. Predicted astrometric signals
Belokurov, Vasily; Evans, N. Wyn; Penoyre, Zephyr
We examine the capacity to identify binary systems from astrometric errors and deviations alone. Until the release of the fourth Gaia data release, we lack the full astrometric time-series that the satellite records, but as we show can still infer the presence of binaries from the best-fitting models, and their error, already available. We generat…