Search Publications
The Open Flux Problem
Liu, Y.; Arge, C. N.; Henney, C. J. +9 more
The heliospheric magnetic field is of pivotal importance in solar and space physics. The field is rooted in the Sun’s photosphere, where it has been observed for many years. Global maps of the solar magnetic field based on full-disk magnetograms are commonly used as boundary conditions for coronal and solar wind models. Two primary observational c…
The Stellar Initial Mass Function in Early-type Galaxies from Absorption Line Spectroscopy. III. Radial Gradients
van Dokkum, Pieter; Romanowsky, Aaron J.; Conroy, Charlie +2 more
There is good evidence that the centers of massive early-type galaxies have a bottom-heavy stellar initial mass function (IMF) compared to that of the Milky Way. Here we study the radial variation of the IMF within such galaxies, using a combination of high-quality Keck spectroscopy and a new suite of stellar population synthesis models that cover…
The Green Bank Ammonia Survey: First Results of NH3 Mapping of the Gould Belt
Caselli, Paola; Di Francesco, James; Rosolowsky, Erik +23 more
We present an overview of the first data release (DR1) and first-look science from the Green Bank Ammonia Survey (GAS). GAS is a Large Program at the Green Bank Telescope to map all Gould Belt star-forming regions with {A}{{V}}≳ 7 mag visible from the northern hemisphere in emission from NH3 and other key molecular tracers. T…
Magnetic Properties of Solar Active Regions That Govern Large Solar Flares and Eruptions
Toriumi, Shin; Harra, Louise K.; Nagashima, Kaori +2 more
Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim of understanding the magnetic properties that govern such flares and eruptions, we systematically survey all flare events with Geostationary Orbiting Environmental Satellite levels of ≥M5.0 within 45° from disk center between…
Quasar-mode Feedback in Nearby Type 1 Quasars: Ubiquitous Kiloparsec-scale Outflows and Correlations with Black Hole Properties
Veilleux, Sylvain; Rupke, David S. N.; Gültekin, Kayhan
The prevalence and properties of kiloparsec-scale outflows in nearby Type 1 quasars have been the subject of little previous attention. This work presents Gemini integral field spectroscopy of 10 Type 1 radio-quiet quasars at z< 0.3. The excellent image quality, coupled with a new technique to remove the point-spread function using spectral inf…
The Environment of the Binary Neutron Star Merger GW170817
Troja, E.; Im, M.; Fox, O. D. +37 more
We present Hubble Space Telescope (HST) and Chandra imaging, combined with Very Large Telescope MUSE integral field spectroscopy of the counterpart and host galaxy of the first binary neutron star merger detected via gravitational-wave emission by LIGO and Virgo, GW170817. The host galaxy, NGC 4993, is an S0 galaxy at z = 0.009783. There is eviden…
Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628
Schaerer, D.; Östlin, G.; Herrero, A. +54 more
We report the large effort that is producing comprehensive high-level young star cluster (YSC) catalogs for a significant fraction of galaxies observed with the Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. We present the methodology developed to extract cluster positions, verify their genuine nature, produce multiband photometry…
The Radio Spectral Energy Distribution and Star-formation Rate Calibration in Galaxies
Boquien, M.; De Looze, I.; Murphy, E. J. +17 more
We study the spectral energy distribution (SED) of the radio continuum (RC) emission from the Key Insight in Nearby Galaxies Emitting in Radio (KINGFISHER) sample of nearby galaxies to understand the energetics and origin of this emission. Effelsberg multi-wavelength observations at 1.4, 4.8, 8.4, and 10.5 GHz combined with archive data allow us, …
Massive Warm/Hot Galaxy Coronae as Probed by UV/X-Ray Oxygen Absorption and Emission. I. Basic Model
Faerman, Yakov; Sternberg, Amiel; McKee, Christopher F.
We construct an analytic phenomenological model for extended warm/hot gaseous coronae of L* galaxies. We consider UV O VI Cosmic Origins Spectrograph (COS)-Halos absorption line data in combination with Milky Way (MW) X-ray O vii and O viii absorption and emission. We fit these data with a single model representing the COS-Halos galaxie…
Active Cryovolcanism on Europa?
Spencer, J. R.; Sparks, W. B.; Hand, K. P. +4 more
Evidence for plumes of water on Europa has previously been found using the Hubble Space Telescope using two different observing techniques. Roth et al. found line emission from the dissociation products of water. Sparks et al. found evidence for off-limb continuum absorption as Europa transited Jupiter. Here, we present a new transit observation o…