Search Publications
A galaxy lacking dark matter
Mowla, Lamiya; van Dokkum, Pieter; Romanowsky, Aaron J. +9 more
Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky…
The onset of star formation 250 million years after the Big Bang
Ouchi, Masami; Harikane, Yuichi; Inoue, Akio K. +21 more
A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang1-3. The abundance of star-forming galaxies is known to decline4,5 from redshifts of about 6 to 10, but a key question is the extent of star formation …
Helium in the eroding atmosphere of an exoplanet
Ehrenreich, D.; Udry, S.; Bourrier, V. +20 more
Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres1. Searches for…
Observations of the missing baryons in the warm-hot intergalactic medium
Piro, L.; Shull, J. M.; Fiore, F. +18 more
It has been known for decades that the observed number of baryons in the local Universe falls about 30-40 per cent short1,2 of the total number of baryons predicted3 by Big Bang nucleosynthesis, as inferred4,5 from density fluctuations of the cosmic microwave background and seen during the first 2-3 billion years o…
Galaxy growth in a massive halo in the first billion years of cosmic history
Bayliss, M. B.; Béthermin, M.; Murphy, E. J. +34 more
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly—the first few hu…
Rotation in [C II]-emitting gas in two galaxies at a redshift of 6.8
Holwerda, Benne W.; Carniani, Stefano; Maiolino, Roberto +10 more
The earliest galaxies are thought to have emerged during the first billion years of cosmic history, initiating the ionization of the neutral hydrogen that pervaded the Universe at this time. Studying this ‘epoch of reionization’ involves looking for the spectral signatures of ancient galaxies that are, owing to the expansion of the Universe, now v…
Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua)
Chambers, Kenneth C.; Wainscoat, Richard J.; Weaver, Harold A. +14 more
'Oumuamua (1I/2017 U1) is the first known object of interstellar origin to have entered the Solar System on an unbound and hyperbolic trajectory with respect to the Sun. Various physical observations collected during its visit to the Solar System showed that it has an unusually elongated shape and a tumbling rotation state and that the physical pr…
Nearly all the sky is covered by Lyman-α emission around high-redshift galaxies
Inami, H.; Steinmetz, M.; Richard, J. +22 more
Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, that are fed by inflows from the intergalactic medium and by outflows from galactic winds. Absorption-line measurements along the lines of sight to bright and rare background quasars indicate that this circumgalactic medium extends far beyond the starlight seen in galaxies, but v…
An absolute sodium abundance for a cloud-free `hot Saturn' exoplanet
Fortney, J. J.; Helling, Ch.; Burgasser, A. J. +20 more
Broad absorption signatures from alkali metals, such as the sodium (Na i) and potassium (K i) resonance doublets, have long been predicted in the optical atmospheric spectra of cloud-free irradiated gas giant exoplanets1-3. However, observations have revealed only the narrow cores of these features rather than the full pressure-broadene…
A population of luminous accreting black holes with hidden mergers
Lu, Jessica R.; Schawinski, Kevin; Sartori, Lia F. +11 more
Major galaxy mergers are thought to play an important part in fuelling the growth of supermassive black holes1. However, observational support for this hypothesis is mixed, with some studies showing a correlation between merging galaxies and luminous quasars2,3 and others showing no such association4,5. Recent obse…