Search Publications
Abundant hydrocarbons in the disk around a very-low-mass star
Waters, L. B. F. M.; Olofsson, G.; Kamp, I. +40 more
Very-low-mass stars (those less than 0.3 solar masses) host orbiting terrestrial planets more frequently than other types of stars. The compositions of those planets are largely unknown but are expected to relate to the protoplanetary disk in which they form. We used James Webb Space Telescope mid-infrared spectroscopy to investigate the chemical …
Optical polarization from colliding stellar stream shocks in a tidal disruption event
Blinov, D.; Liodakis, I.; Berton, M. +9 more
A tidal disruption event (TDE) occurs when a supermassive black hole rips apart a passing star. Part of the stellar material falls toward the black hole, forming an accretion disk that in some cases launches a relativistic jet. We performed optical polarimetry observations of a TDE, AT 2020mot. We find a peak linear polarization degree of 25 ± 4%,…
The dark matter interpretation of the 3.5-keV line is inconsistent with blank-sky observations
Safdi, Benjamin R.; Dessert, Christopher; Rodd, Nicholas L.
Observations of nearby galaxies and galaxy clusters have reported an unexpected x-ray emission line around 3.5 kilo-electron volts (keV). Proposals to explain this line include decaying dark matter—in particular, that the decay of sterile neutrinos with a mass around 7 keV could match the available data. If this interpretation is correct, the 3.5-…
A radio ridge connecting two galaxy clusters in a filament of the cosmic web
Brunetti, G.; Enßlin, T. A.; Shimwell, T. W. +26 more
Galaxy clusters are the most massive gravitationally bound structures in the Universe. They grow by accreting smaller structures in a merging process that produces shocks and turbulence in the intracluster gas. We observed a ridge of radio emission connecting the merging galaxy clusters Abell 0399 and Abell 0401 with the Low-Frequency Array (LOFAR…
A loud quasi-periodic oscillation after a star is disrupted by a massive black hole
Steiner, James F.; Remillard, Ronald A.; Homan, Jeroen +9 more
The tidal forces close to massive black holes can rip apart stars that come too close to them. As the resulting stellar debris spirals toward the black hole, the debris heats up and emits x-rays. We report observations of a stable 131-second x-ray quasi-periodic oscillation from the tidal disruption event ASASSN-14li. Assuming the black hole mass …
Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
Henning, Thomas; Dreizler, Stefan; Sánchez-López, Alejandro +25 more
Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-α line in the far ultraviolet region, which is strongly affected by inter…
A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger
Bondi, M.; Lundqvist, P.; Clements, D. L. +33 more
Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg at infrared and radio wavelengths but was not luminous at …
An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907
Wolter, Anna; Esposito, Paolo; Turolla, Roberto +20 more
Ultraluminous x-ray sources (ULXs) in nearby galaxies shine brighter than any x-ray source in our Galaxy. ULXs are usually modeled as stellar-mass black holes (BHs) accreting at very high rates or intermediate-mass BHs. We present observations showing that NGC 5907 ULX is instead an x-ray accreting neutron star (NS) with a spin period evolving fro…
Black hole feedback in the luminous quasar PDS 456
Harrison, F. A.; Stern, D.; Behar, E. +17 more
The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spheri…
The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud
Klochkov, D.; Santangelo, A.; Quirrenbach, A. +226 more
The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known, N 157B; the radio-loud supe…