Search Publications
The Panchromatic Hubble Andromeda Treasury. XI. The Spatially Resolved Recent Star Formation History of M31
Bell, Eric F.; Monachesi, Antonela; Dolphin, Andrew E. +15 more
We measure the recent star formation history (SFH) across M31 using optical images taken with the Hubble Space Telescope as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We fit the color-magnitude diagrams in ∼9000 regions that are ∼100 pc × 100 pc in projected size, covering a 0.5 square degree area (∼380 kpc2, deprojected…
A Deep Hubble Space Telescope and Keck Search for Definitive Identification of Lyman Continuum Emitters at z~3.1
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +13 more
Narrowband imaging of the rest-frame Lyman continuum (LyC) of galaxies at z∼ 3.1 has produced a large number of candidate LyC-emitting galaxies. These samples are contaminated by galaxies at lower redshift. To better understand LyC escape, we need an uncontaminated sample of galaxies that emit strongly in the LyC. Here we present deep Hubble Space…
Coordinated X-Ray, Ultraviolet, Optical, and Radio Observations of the PSR J1023+0038 System in a Low-mass X-Ray Binary State
Deller, Adam T.; Lyne, Andrew G.; Bogdanov, Slavko +14 more
The PSR J1023+0038 binary system hosts a neutron star and a low-mass, main-sequence-like star. It switches on year timescales between states as an eclipsing radio millisecond pulsar and a low-mass X-ray binary (LMXB). We present a multi-wavelength observational campaign of PSR J1023+0038 in its most recent LMXB state. Two long XMM-Newton observati…
Temporal Evolution of Chromospheric Evaporation: Case Studies of the M1.1 Flare on 2014 September 6 and X1.6 Flare on 2014 September 10
Reeves, Katharine K.; Chen, Bin; Liu, Wei +3 more
With observations from the Interface Region Imaging Spectrograph, we track the complete evolution of ∼11 MK evaporation flows in an M1.1 flare on 2014 September 6 and an X1.6 flare on 2014 September 10. These hot flows, as indicated by the blueshifted Fe xxi 1354.08 Å line, evolve smoothly with a velocity decreasing exponentially from ∼200 km s
Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy
Wakker, Bart P.; Lehner, Nicolas; Howk, J. Christopher
We demonstrate the presence of an extended and massive circumgalactic medium (CGM) around Messier 31 using archival HST Cosmic Origins Spectrograph ultraviolet spectroscopy of 18 QSOs projected within two virial radii of M31 ({{R}vir}=300 kpc). We detect absorption from Si iii at -300≲ {{v}LSR}≲ -150 km s-1 toward …
Bayesian Ages for Early-type Stars from Isochrones Including Rotation, and a Possible Old Age for the Hyades
Huang, Chelsea X.; Brandt, Timothy D.
We combine recently computed models of stellar evolution using a new treatment of rotation with a Bayesian statistical framework to constrain the ages and other properties of early-type stars. We find good agreement for early-type stars and clusters with known young ages, including β Pictoris, the Pleiades, and the Ursa Majoris moving group. Howev…
The Ages, Metallicities, and Element Abundance Ratios of Massive Quenched Galaxies at z ≈ 1.6
Daddi, E.; Carollo, C. M.; Gobat, R. +8 more
We investigate the stellar population properties of a sample of 24 massive quenched galaxies at 1.25< zspec< 2.09 identified in the COSMOS field with our Subaru/Multi-object Infrared Camera and Spectrograph near-IR spectroscopic observations. Tracing the stellar population properties as close to their major formation epoch as poss…
Measuring the Mass of the Central Black Hole in the Bulgeless Galaxy NGC 4395 from Gas Dynamical Modeling
Ho, Luis C.; Neumayer, Nadine; Barth, Aaron J. +7 more
NGC 4395 is a bulgeless spiral galaxy, harboring one of the nearest known type 1 Seyfert nuclei. Although there is no consensus on the mass of its central engine, several estimates suggest it is one of the lightest massive black holes (MBHs) known. We present the first direct dynamical measurement of the mass of this MBH from a combination of two-…
The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. I. Very Large Array Detections of Dual AGNs and AGN Outflows
Cooper, M. C.; Comerford, J. M.; Greene, J. E. +3 more
We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have 2 optical AGN emission components separated by >0.″2, and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without f…
High-J CO versus Far-infrared Relations in Normal and Starburst Galaxies
Daddi, Emanuele; van der Werf, Paul; Liu, Daizhong +4 more
We present correlations between 9 CO transitions (J=4-3 to 12-11) and beam-matched far-infrared (far-IR) luminosities ({L}{FIR,b}) among 167 local galaxies, using Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (SPIRE; FTS) spectroscopic data and Photoconductor Array Camera and Spectrometer (PACS) photo…