Search Publications
Time Dependent Nonequilibrium Ionization of Transition Region Lines Observed with IRIS
Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo H. +1 more
The properties of nonstatistical equilibrium ionization of silicon and oxygen ions are analyzed in this work. We focus on five solar targets (quiet Sun; coronal hole; plage; quiescent active region, AR; and flaring AR) as observed with the Interface Region Imaging Spectrograph (IRIS). IRIS is best suited for this work owing to the high cadence (up…
The Local Black Hole Mass Function Derived from the MBH-P and the MBH-n Relations
Mutlu-Pakdil, Burçin; Davis, Benjamin L.; Seigar, Marc S.
We present a determination of the supermassive black hole (SMBH) mass function for early- and late-type galaxies in the nearby universe (z < 0.0057), established from a volume-limited sample consisting of a statistically complete collection of the brightest spiral galaxies in the southern hemisphere. The sample is defined by limiting luminosity…
Constraining AGN Feedback in Massive Ellipticals with South Pole Telescope Measurements of the Thermal Sunyaev-Zel'dovich Effect
Cohen, Seth; Joshi, Bhavin; Scannapieco, Evan +2 more
Energetic feedback due to active galactic nuclei (AGNs) is likely to play an important role in the observed anti-hierarchical trend in the evolution of galaxies, and yet the energy injected into the circumgalactic medium by this process is largely unknown. One promising approach to constrain this feedback is through measurements of spectral distor…
When Shock Waves Collide
Hartigan, P.; Frank, A.; Hansen, E. +10 more
Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are impo…
The UV-Optical Color Gradients in Star-forming Galaxies at 0.5 < z < 1.5: Origins and Link to Galaxy Assembly
Barro, Guillermo; Faber, S. M.; Koo, David C. +10 more
The rest-frame UV-optical (I.e., NUV - B) color index is sensitive to the low-level recent star formation and dust extinction, but it is insensitive to the metallicity. In this Letter, we have measured the rest-frame NUV - B color gradients in ∼1400 large (r e > 0.″18), nearly face-on (b/a > 0.5) main sequence star-forming galaxie…
Discovery of a Makemakean Moon
Buie, Marc W.; Noll, Keith S.; Parker, Alex H. +1 more
We describe the discovery of a satellite in orbit about the dwarf planet (136472) Makemake. This satellite, provisionally designated S/2015 (136472) 1, was detected in imaging data collected with the Hubble Space Telescope’s Wide Field Camera 3 on UTC 2015 April 27 at 7.80 ± 0.04 mag fainter than Makemake and at a separation of 0.″57. It likely ev…
A New Perspective of the Radio Bright Zone at The Galactic Center: Feedback from Nuclear Activities
Morris, Mark R.; Goss, W. M.; Zhao, Jun-Hui
New observations of Sgr A have been carried out with the Jansky VLA in the B and C arrays using the broadband (2 GHz) continuum mode at 5.5 GHz. The field of view covers the central 13‧ (30 pc) region of the radio-bright zone at the Galactic center. Using the multi-scale and multi-frequency-synthesis (MS-MFS) algorithms in CASA, we have imaged Sgr…
Molecular Hydrogen Absorption from the Halo of a z ∼ 0.4 Galaxy
Charlton, Jane C.; Kacprzak, Glenn G.; Churchill, Christopher W. +1 more
Lyman- and Werner-band absorption of molecular hydrogen ({{{H}}}2) is detected in ∼50% of low-redshift (z\lt 1) DLAs/sub-DLAs with N({{{H}}}2) \gt {10}14.4 cm-2. However, the true origin(s) of the {{{H}}}2-bearing gas remain elusive. Here we report a new detection of an {{{H}}}2 abs…
Modeling the Solar Wind at the Ulysses, Voyager, and New Horizons Spacecraft
McComas, D. J.; Pogorelov, N. V.; Zank, G. P. +2 more
The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulat…
Broadband Observations of High Redshift Blazars
Stalin, C. S.; Fabian, A. C.; Parker, M. L. +1 more
We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2-3303 (z = 2.40) using quasi-simultaneous data from the Swift, Nuclear Spectroscopic Telescope Array (NuSTAR) and the Fermi-Large Area Telescope (LAT) and also archival XMM-Newton observ…