Search Publications
UV Spectral Slopes at z = 6-9 in the Hubble Frontier Fields: Lack of Evidence for Unusual or Population III Stellar Populations
Conselice, Christopher J.; Bhatawdekar, Rachana
We present new measurements of the UV spectral slope β for galaxies at z = 6-9 in the Frontier Field cluster MACS J0416.1-2403 and its parallel field to an unprecedented level of low stellar mass. We fit synthetic stellar population models to the observed spectral energy distribution and calculate β by fitting a power law to the best-fit spectrum.…
Large metallicity variations in the Galactic interstellar medium
Jenkins, Edward B.; Petitjean, Patrick; Fox, Andrew J. +5 more
The interstellar medium (ISM) comprises gases at different temperatures and densities, including ionized, atomic and molecular species, and dust particles1. The neutral ISM is dominated by neutral hydrogen2 and has ionization fractions of up to eight per cent3. The concentration of chemical elements heavier than he…
PENELLOPE: The ESO data legacy program to complement the Hubble UV Legacy Library of Young Stars (ULLYSES). I. Survey presentation and accretion properties of Orion OB1 and σ-Orionis
Lodato, G.; France, K.; Mendigutía, I. +69 more
The evolution of young stars and disks is driven by the interplay of several processes, notably the accretion and ejection of material. These processes, critical to correctly describe the conditions of planet formation, are best probed spectroscopically. Between 2020 and 2022, about 500orbits of the Hubble Space Telescope (HST) are being devoted i…
Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b
Fang, Min; Herczeg, Gregory J.; Schneider, Glenn +6 more
Recent discoveries of young exoplanets within their natal disks offer exciting opportunities to study ongoing planet formation. In particular, a planet's mass accretion rate can be constrained by observing the accretion-induced excess emission. So far, planetary accretion is only probed by the Hα line, which is then converted to a total accretion …
VINTERGATAN III: how to reset the metallicity of the Milky Way
Feuillet, Diane K.; Ryde, Nils; Bensby, Thomas +5 more
Using the cosmological zoom simulation VINTERGATAN, we present a new scenario for the onset of star formation at the metal-poor end of the low-[α/Fe] sequence in a Milky Way-like galaxy. In this scenario, the galaxy is fuelled by two distinct gas flows. One is enriched by outflows from massive galaxies, but not the other. While the former feeds th…
A Local Baseline of the Black Hole Mass Scaling Relations for Active Galaxies. IV. Correlations Between MBH and Host Galaxy σ, Stellar Mass, and Luminosity
Treu, Tommaso; Auger, Matthew W.; Birrer, Simon +6 more
The tight correlations between the mass of supermassive black holes (MBH) and their host-galaxy properties have been of great interest to the astrophysical community, but a clear understanding of their origin and fundamental drivers still eludes us. The local relations for active galaxies are interesting in their own right and form the …
Revealing the Accretion Physics of Supermassive Black Holes at Redshift z ∼ 7 with Chandra and Infrared Observations
Hennawi, Joseph F.; Fan, Xiaohui; Walter, Fabian +14 more
X-ray emission from quasars has been detected up to redshift z = 7.5, although only limited to a few objects at z > 6.5. In this work, we present new Chandra observations of five z > 6.5 quasars. By combining with archival Chandra observations of six additional z > 6.5 quasars, we perform a systematic analysis on the X-ray properties of t…
Testing the effect of H0 on fσ8 tension using a Gaussian process method
Xu, Lixin; Li, En-Kun; Du, Minghui +2 more
Using the fσ8(z) redshift space distortion (RSD) data, the $\sigma _8^0\!-\!\Omega _\mathrm{ m}^0$ tension is studied utilizing a parametrization of growth rate f(z) = Ωm(z)γ. Here, f(z) is derived from the expansion history H(z) which is reconstructed from the observational Hubble data applying the Gaussian proces…
The diffuse γ-ray background is dominated by star-forming galaxies
Krumholz, Mark R.; Crocker, Roland M.; Roth, Matt A. +1 more
The Fermi Gamma-ray Space Telescope has revealed a diffuse γ-ray background at energies from 0.1 gigaelectronvolt to 1 teraelectronvolt, which can be separated into emission from our Galaxy and an isotropic, extragalactic component1. Previous efforts to understand the latter have been hampered by the lack of physical models capable of p…
Two Young Planetary Systems around Field Stars with Ages between 20 and 320 Myr from TESS
Torres, Guillermo; Hellier, Coel; Bieryla, Allyson +46 more
Planets around young stars trace the early evolution of planetary systems. We report the discovery and validation of two planetary systems with ages ≲300 Myr from observations by the Transiting Exoplanet Survey Satellite (TESS). The $40\mbox{--}320$ Myr old G star TOI-251 hosts a ${2.74}_{-0.18}^{+0.18}\,{R}_{\oplus }$ mini-Neptune with a $4.94$ d…