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Constraining the Properties of Dark Matter with Observations of the Cosmic Microwave Background
Kopp, Michael; Skordis, Constantinos; Thomas, Daniel B.
We examine how the properties of dark matter, parameterized by an equation-of-state parameter w and two perturbative generalized dark matter (GDM) parameters, c 2 s (the sound speed) and {c}{vis}2 (the viscosity), are constrained by existing cosmological data, particularly the Planck 2015 data release.…
Giant Metrewave Radio Telescope observations of neutral atomic hydrogen gas in the COSMOS field at z ∼ 0.37
Chengalur, Jayaram N.; Colless, Matthew; Rhee, Jonghwan +2 more
We present the results of H I spectral stacking analysis of Giant Metrewave Radio Telescope (GMRT) observations targeting the Cosmological Evolution Survey (COSMOS) field. The GMRT data cube contains 474 field galaxies with redshifts known from the zCOSMOS-bright 10 k catalogue. Spectra for the galaxies are co-added and the stacked spectrum allows…
Gaia FGK benchmark stars: new candidates at low metallicities
Gilmore, G.; Randich, S.; Soubiran, C. +10 more
Context. We have entered an era of large spectroscopic surveys in which we can measure, through automated pipelines, the atmospheric parameters and chemical abundances for large numbers of stars. Calibrating these survey pipelines using a set of "benchmark stars" in order to evaluate the accuracy and precision of the provided parameters and abunda…
A cold-wet middle-latitude environment on Mars during the Hesperian-Amazonian transition: Evidence from northern Arabia valleys and paleolakes
Moore, Jeffrey M.; Wilson, Sharon A.; Howard, Alan D. +1 more
The growing inventory of post-Noachian fluvial valleys may represent a late, widespread episode of aqueous activity on Mars, contrary to the paradigm that fluvial activity largely ceased around the Noachian-Hesperian boundary. Fresh shallow valleys (FSVs) are widespread from ~30 to 45° in both hemispheres with a high concentration in northern Arab…
Search for associations containing young stars (SACY). VII. New stellar and substellar candidate members in the young associations
Bayo, A.; Montes, D.; Sterzik, M. F. +5 more
Context. The young associations offer us one of the best opportunities to study the properties of young stellar and substellar objects and to directly image planets thanks to their proximity (<200 pc) and age (≈5-150 Myr). However, many previous works have been limited to identifying the brighter, more active members (≈1 M⊙) owing to…
Constraints on dark-matter properties from large-scale structure
Kunz, Martin; Nesseris, Savvas; Sawicki, Ignacy
We use large-scale cosmological observations to place constraints on the dark-matter pressure, sound speed and viscosity and infer a limit on the mass of warm-dark-matter particles. Measurements of the cosmic microwave background anisotropies constrain the equation of state and sound speed of the dark matter (DM) at last scattering at the per mill…
Nature of the Soft ULX in NGC 247: Super-Eddington Outflow and Transition between the Supersoft and Soft Ultraluminous Regimes
Tao, Lian; Feng, Hua; Grisé, Fabien +1 more
We report on XMM-Newton/Chandra/Swift/Hubble Space Telescope observations of the ultraluminous X-ray source (ULX) in NGC 247, which is found to make transitions between the supersoft ultraluminous (SSUL) regime with a spectrum dominated by a cool (∼0.1 keV) blackbody component and the soft ultraluminous (SUL) regime with comparable luminosities sh…
A HIFI view on circumstellar H2O in M-type AGB stars: radiative transfer, velocity profiles, and H2O line cooling
Olofsson, H.; Justtanont, K.; De Beck, E. +4 more
Aims: We aim to constrain the temperature and velocity structures, and H2O abundances in the winds of a sample of M-type asymptotic giant branch (AGB) stars. We further aim to determine the effect of H2O line cooling on the energy balance in the inner circumstellar envelope.
Methods: We use two radiative-transfer co…
Pre-inflationary relics in the CMB?
Gruppuso, A.; Mandolesi, N.; Natoli, P. +2 more
String Theory and Supergravity allow, in principle, to follow the transition of the inflaton from pre-inflationary fast roll to slow roll. This introduces an infrared depression in the primordial power spectrum that might have left an imprint in the CMB anisotropy, if it occurred at accessible wavelengths. We model the effect extending Λ CDM with …
Spatially resolved integral field spectroscopy of the ionized gas in IZw18
Kunth, D.; Durret, F.; Brinchmann, J. +6 more
We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding …