Search Publications
A Population of Bona Fide Intermediate-mass Black Holes Identified as Low-luminosity Active Galactic Nuclei
Boutsia, Konstantina; Chilingarian, Igor V.; Zolotukhin, Ivan Yu. +4 more
Nearly every massive galaxy harbors a supermassive black hole (SMBH) in its nucleus. SMBH masses are millions to billions of solar mass, and they correlate with properties of spheroids of their host galaxies. While the SMBH growth channels, mergers, and gas accretion are well established, their origin remains uncertain: they could have emerged eit…
A new method for unveiling open clusters in Gaia. New nearby open clusters confirmed by DR2
Castro-Ginard, A.; Jordi, C.; Luri, X. +4 more
Context. The publication of the Gaia Data Release 2 (Gaia DR2) opens a new era in astronomy. It includes precise astrometric data (positions, proper motions, and parallaxes) for more than 1.3 billion sources, mostly stars. To analyse such a vast amount of new data, the use of data-mining techniques and machine-learning algorithms is mandatory.
The origin of ultra diffuse galaxies: stellar feedback and quenching
Hopkins, P. F.; Wetzel, A.; El-Badry, K. +5 more
We test if the cosmological zoom-in simulations of isolated galaxies from the FIRE project reproduce the properties of ultra diffuse galaxies (UDGs). We show that outflows that dynamically heat galactic stars, together with a passively aging stellar population after imposed quenching, naturally reproduce the observed population of red UDGs, withou…
Starbursts in and out of the star-formation main sequence
Daddi, E.; Elbaz, D.; Franco, M. +13 more
Aims: We use high-resolution continuum images obtained with the Atacama Large Millimeter Array (ALMA) to probe the surface density of star formation in z ~ 2 galaxies and study the different physical properties between galaxies within and above the star-formation main sequence of galaxies.
Methods: We use ALMA images at 870 µm with…
Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
Owen, James E.; Triaud, Amaury H. M. J.; Wakeford, Hannah R. +14 more
Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres3-6. Hydrogen in particular is a powerful greenhouse gas that may…
Hubble PanCET: an extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b
Sanz-Forcada, J.; Ehrenreich, D.; Lecavelier des Etangs, A. +16 more
GJ 3470b is a warm Neptune transiting an M-dwarf star at the edge of the evaporation desert. It offers the possibility of investigating how low-mass, close-in exoplanets evolve under the irradiation from their host stars. We observed three transits of GJ 3470b in the Lyman-α line with the Hubble Space Telescope (HST) as part of the Panchromatic Co…
Vacuum phase transition solves the H0 tension
Di Valentino, Eleonora; Melchiorri, Alessandro; Linder, Eric V.
Taking the Planck cosmic microwave background data and the more direct Hubble constant measurement data as unaffected by systematic offsets, the values of the Hubble constant H0 interpreted within the Λ CDM cosmological constant and cold dark matter cosmological model are in ∼3.3 σ tension. We show that the Parker vacuum metamorphosis (…
A peculiar low-luminosity short gamma-ray burst from a double neutron star merger progenitor
Li, Y.; Shao, L.; Zhang, S. +15 more
Double neutron star (DNS) merger events are promising candidates of short gamma-ray burst (sGRB) progenitors as well as high-frequency gravitational wave (GW) emitters. On August 17, 2017, such a coinciding event was detected by both the LIGO-Virgo gravitational wave detector network as GW170817 and Gamma-Ray Monitor on board NASA's Fermi Space Te…
The Chemical Homogeneity of Sun-like Stars in the Solar Neighborhood
Dreizler, Stefan; Bedell, Megan; Casagrande, Luca +9 more
The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large intrinsic variation in the elemental abundance patterns of stars with similar overall metal content. However, system…
Testing warm Comptonization models for the origin of the soft X-ray excess in AGNs
Bianchi, S.; Cappi, M.; Petrucci, P. -O. +5 more
The X-ray spectra of many active galactic nuclei (AGNs) show a soft X-ray excess below 1-2 keV on top of the extrapolated high-energy power law. The origin of this component is uncertain. It could be a signature of relativistically blurred, ionized reflection or the high-energy tail of thermal Comptonization in a warm (kT 1 keV), optically thick (…