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Observational constraints on the specific accretion-rate distribution of X-ray-selected AGNs
Georgakakis, A.; Salvato, M.; Schulze, A. +5 more
This paper estimates the specific accretion-rate distribution of AGNs using a sample of 4821 X-ray sources from both deep and shallow surveys. The specific accretion-rate distribution is used as a proxy of the Eddington ratio and is defined as the probability of a galaxy with a given stellar mass and redshift hosting an active nucleus with a certa…
The earliest phases of high-mass star formation, as seen in NGC 6334 by Herschel-HOBYS
Bernard, J. -P.; Martin, P. G.; Hill, T. +33 more
Aims: To constrain models of high-mass star formation, the Herschel-HOBYS key program aims at discovering massive dense cores (MDCs) able to host the high-mass analogs of low-mass prestellar cores, which have been searched for over the past decade. We here focus on NGC 6334, one of the best-studied HOBYS molecular cloud complexes.
Method…
The Extent of Chemically Enriched Gas around Star-forming Dwarf Galaxies
Johnson, Sean D.; Chen, Hsiao-Wen; Mulchaey, John S. +2 more
Supernova driven winds are often invoked to remove chemically enriched gas from dwarf galaxies to match their low observed metallicities. In such shallow potential wells, outflows may produce massive amounts of enriched halo gas (circumgalactic medium, CGM) and pollute the intergalactic medium (IGM). Here, we present a survey of the CGM and IGM ar…
Turbulent Kinetic Energy in the Energy Balance of a Solar Flare
Harra, L. K.; Kontar, E. P.; Perez, J. E. +5 more
The energy released in solar flares derives from a reconfiguration of magnetic fields to a lower energy state, and is manifested in several forms, including bulk kinetic energy of the coronal mass ejection, acceleration of electrons and ions, and enhanced thermal energy that is ultimately radiated away across the electromagnetic spectrum from opti…
COS-burst: Observations of the Impact of Starburst-driven Winds on the Properties of the Circum-galactic Medium
Heckman, Timothy; Wild, Vivienne; Borthakur, Sanchayeeta +2 more
We report on observations made with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) using background quasi-stellar objects to probe the circum-galactic medium (CGM) around 17 low-redshift galaxies that are undergoing or have recently undergone a strong starburst (the COS-Burst program). The sightlines extend out to roughl…
Does a Differentiated, Carbonate-rich, Rocky Object Pollute the White Dwarf SDSS J104341.53+085558.2?
Dufour, P.; Melis, Carl
We present spectroscopic observations of the dust- and gas-enshrouded, polluted, single white dwarf star SDSS J104341.53+085558.2 (hereafter SDSS J1043+0855). Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet spectra combined with deep Keck HIRES optical spectroscopy reveal the elements C, O, Mg, Al, Si, P, S, Ca, Fe, and Ni and e…
Witnessing the growth of the nearest galaxy cluster: thermodynamics of the Virgo Cluster outskirts
Simionescu, A.; Allen, S. W.; Werner, N. +2 more
We present results from Suzaku Key Project observations of the Virgo Cluster, the nearest galaxy cluster to us, mapping its X-ray properties along four long 'arms' extending beyond the virial radius. The entropy profiles along all four azimuths increase with radius, then level out beyond ∼0.5r200, while the average pressure at large rad…
Active galactic nuclei vs. host galaxy properties in the COSMOS field
Berta, S.; Pozzi, F.; Salvato, M. +13 more
Context. The coeval active galactic nuclei (AGN) and galaxy evolution, and the observed local relations between super massive black holes (SMBHs) and galaxy properties suggest some sort of connection or feedback between SMBH growth (I.e., AGN activity) and galaxy build-up (I.e., star formation history).
Aims: We looked for correlations betwee…
Microlensing of Extremely Magnified Stars near Caustics of Galaxy Clusters
Miralda-Escudé, Jordi; Dai, Liang; Venumadhav, Tejaswi
Recent observations of lensed galaxies at cosmological distances have detected individual stars that are extremely magnified when crossing the caustics of lensing clusters. In idealized cluster lenses with smooth mass distributions, two images of a star of radius R approaching a caustic brighten as {t}-1/2 and reach a peak magnification…
The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation
Alexander, D. M.; Wang, L.; De Zotti, G. +15 more
We investigate the mean star formation rates (SFRs) in the host galaxies of ∼3000 optically selected quasi-stellar objects (QSOs) from the Sloan Digital Sky Survey within the Herschel-ATLAS fields, and a radio-luminous subsample covering the redshift range of z = 0.2-2.5. Using Wide-field Infrared Survey Explorer (WISE) and Herschel photometry (12…