Search Publications
High-molecular-weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko
Krüger, Harald; Haerendel, Gerhard; Langevin, Yves +39 more
The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley. Such matter is generally thought to have originated in the interstellar medium, but it might have formed in the solar nebula—the cloud of gas and dust that was left…
A 17-billion-solar-mass black hole in a group galaxy with a diffuse core
Ma, Chung-Pei; Greene, Jenny E.; Blakeslee, John P. +3 more
Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day ‘dormant’ descendants of this population of ‘active’ bla…
Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni
Ponti, G.; Charles, P. A.; Rodriguez, J. +7 more
Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and …
Positron annihilation signatures associated with the outburst of the microquasar V404 Cygni
Beloborodov, Andrei M.; Diehl, Roland; Greiner, Jochen +7 more
Microquasars are stellar-mass black holes accreting matter from a companion star and ejecting plasma jets at almost the speed of light. They are analogues of quasars that contain supermassive black holes of 106 to 1010 solar masses. Accretion in microquasars varies on much shorter timescales than in quasars and occasionally p…
A massive, quiescent, population II galaxy at a redshift of 2.1
Siana, Brian; van Dokkum, Pieter G.; Choi, Jieun +7 more
Unlike spiral galaxies such as the Milky Way, the majority of the stars in massive elliptical galaxies were formed in a short period early in the history of the Universe. The duration of this formation period can be measured using the ratio of magnesium to iron abundance ([Mg/Fe]) in spectra, which reflects the relative enrichment by core-collapse…
Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni
Ruiz, Javier; Enoto, Teruaki; Nogami, Daisaku +65 more
How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed…
Relativistic reverberation in the accretion flow of a tidal disruption event
Miller, Jon M.; Kara, Erin; Dai, Lixin +1 more
Our current understanding of the curved space-time around supermassive black holes is based on actively accreting black holes, which make up only ten per cent or less of the overall population. X-ray observations of that small fraction reveal strong gravitational redshifts that indicate that many of these black holes are rapidly rotating; however,…
Fission and reconfiguration of bilobate comets as revealed by 67P/Churyumov-Gerasimenko
Mottola, Stefano; Steckloff, Jordan; Naidu, Shantanu P. +6 more
The solid, central part of a comet—its nucleus—is subject to destructive processes, which cause nuclei to split at a rate of about 0.01 per year per comet. These destructive events are due to a range of possible thermophysical effects; however, the geophysical expressions of these effects are unknown. Separately, over two-thirds of comet nuclei th…
Ultraluminous X-ray bursts in two ultracompact companions to nearby elliptical galaxies
Romanowsky, Aaron J.; Liu, Jifeng; Strader, Jay +8 more
A flaring X-ray source was found near the galaxy NGC 4697 (ref. 1). Two brief flares were seen, separated by four years. During each flare, the flux increased by a factor of 90 on a timescale of about one minute. There is no associated optical source at the position of the flares, but if the source was at the distance of NGC 4697, then the luminos…
Formation of new stellar populations from gas accreted by massive young star clusters
Faucher-Giguère, Claude-André; Deng, Licai; de Grijs, Richard +4 more
Stars in clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old ‘globular’ clusters—those with ages greater than ten billion years and masses several hundred thousand times that of the Sun—often harbour multiple stellar populations, indicating that more than one star-forming event occu…