Search Publications
Spatially Resolved Dust Maps from Balmer Decrements in Galaxies at z ~ 1.4
van Dokkum, Pieter G.; Franx, Marijn; Whitaker, Katherine E. +6 more
We derive average radial gradients in the dust attenuation toward H II regions in 609 galaxies at z ∼ 1.4, using measurements of the Balmer decrement out to r ∼ 3 kpc. The Balmer decrements are derived from spatially resolved maps of Hα and Hβ emission from the 3D-HST survey. We find that with increasing stellar mass M both the normalization and s…
The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-redshift Galaxies
Carilli, Chris; Bell, Eric F.; Bacon, Roland +29 more
We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an ∼1 arcmin2 region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and c…
VLT FORS2 Comparative Transmission Spectroscopy: Detection of Na in the Atmosphere of WASP-39b from the Ground
Nikolov, Nikolay; Fortney, Jonathan J.; Gibson, Neale P. +5 more
We present transmission spectroscopy of the warm Saturn-mass exoplanet WASP-39b made with the Very Large Telescope FOcal Reducer and Spectrograph (FORS2) across the wavelength range 411-810 nm. The transit depth is measured with a typical precision of 240 parts per million (ppm) in wavelength bins of 10 nm on a V = 12.1 mag star. We detect the sod…
Inferred H⍺ Flux as a Star Formation Rate Indicator at z ~ 4-5: Implications for Dust Properties, Burstiness, and the z = 4-8 Star Formation Rate Functions
Wilkins, Stephen M.; Franx, Marijn; Labbé, Ivo +3 more
We derive Hα fluxes for a large spectroscopic and photometric-redshift-selected sample of sources over GOODS-North and South in the redshift range z = 3.8-5.0 with deep Hubble Space Telescope (HST), Spitzer/IRAC, and ground-based observations. The Hα flux is inferred based on the offset between the IRAC 3.6 µm flux and that predicted from th…
Green Pea Galaxies Reveal Secrets of Lyα Escape
Jaskot, Anne; Malhotra, Sangeeta; Gronke, Max +5 more
We analyze archival Lyα spectra of 12 “Green Pea” galaxies observed with the Hubble Space Telescope, model their Lyα profiles with radiative transfer models, and explore the dependence of the Lyα escape fraction on various properties. Green Pea galaxies are nearby compact starburst galaxies with [O III] λ5007 equivalent widths (EWs) of hundreds of…
Classification and Ranking of Fermi LAT Gamma-ray Sources from the 3FGL Catalog using Machine Learning Techniques
Marelli, M.; Saz Parkinson, P. M.; Falcone, A. D. +3 more
We apply a number of statistical and machine learning techniques to classify and rank gamma-ray sources from the Third Fermi Large Area Telescope Source Catalog (3FGL), according to their likelihood of falling into the two major classes of gamma-ray emitters: pulsars (PSR) or active galactic nuclei (AGNs). Using 1904 3FGL sources that have been id…
A Rich Globular Cluster System in Dragonfly 17: Are Ultra-diffuse Galaxies Pure Stellar Halos?
Peng, Eric W.; Lim, Sungsoon
Observations of nearby galaxy clusters at low surface brightness have identified galaxies with low luminosities, but sizes as large as L ⋆ galaxies, leading them to be dubbed “ultra-diffuse galaxies” (UDGs). The survival of UDGs in dense environments like the Coma cluster suggests that UDGs could reside in much more massive dark halos. …
Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data
Troja, E.; Caraveo, P. A.; Orlando, E. +109 more
We present results from γ-ray observations of the Coma cluster incorporating six years of Fermi-LAT data and the newly released “Pass 8” event-level analysis. Our analysis of the region reveals low-significance residual structures within the virial radius of the cluster that are too faint for a detailed investigation with the current data. Using a…
Deja Vu All Over Again: The Reappearance of Supernova Refsdal
Cenko, S. B.; Molino, A.; Zitrin, A. +19 more
In Hubble Space Telescope (HST) imaging taken on 2014 November 10, four images of supernova (SN) “Refsdal” (redshift z = 1.49) appeared in an Einstein-cross-like configuration (images S1-S4) around an early-type galaxy in the cluster MACS J1149.5+2223 (z = 0.54). Almost all lens models of the cluster have predicted that the SN should reappear with…
A New Approach to Analyzing HST Spatial Scans: The Transmission Spectrum of HD 209458 b
Tsiaras, A.; Waldmann, I. P.; Rocchetto, M. +4 more
The Wide Field Camera 3 on the Hubble Space Telescope is currently one of the most widely used instruments for observing exoplanetary atmospheres, especially with the use of the spatial scanning technique. An increasing number of exoplanets have been studied using this technique as it enables the observation of bright targets without saturating th…