Search Publications
Ion Dynamics at a Rippled Quasi-parallel Shock: 2D Hybrid Simulations
Wang, Shui; Hao, Yufei; Lu, Quanming +1 more
In this paper, two-dimensional hybrid simulations are performed to investigate ion dynamics at a rippled quasi-parallel shock. The results show that the ripples around the shock front are inherent structures of a quasi-parallel shock, and the re-formation of the shock is not synchronous along the surface of the shock front. By following the trajec…
The Distribution of Mass Surface Densities in a High-mass Protocluster
Kainulainen, Jouni; Tan, Jonathan C.; Lim, Wanggi +2 more
We study the probability distribution function (PDF) of mass surface densities, Σ, of infrared dark cloud (IRDC) G028.37+00.07 and its surrounding giant molecular cloud. This PDF constrains the physical processes, such as turbulence, magnetic fields, and self-gravity, that are expected to be controlling cloud structure and star formation activity.…
Observations of Oppositely Directed Umbral Wavefronts Rotating in Sunspots Obtained from the New Solar Telescope of BBSO
Chen, J.; Banerjee, D.; Su, J. T. +7 more
We study the umbral waves as observed by chromospheric imaging observations of two sunspots with the New Solar Telescope at the Big Bear Solar Observatory. We find that the wavefronts (WFs) rotate clockwise and form a one-armed spiral structure in the first sunspot, whereas two- and three-armed structures arise in the second sunspot where the WFs …
Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy Clusters
Bulbul, Esra; Markevitch, Maxim; Smith, Randall K. +5 more
We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2σ -significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sa…
Broad [C II] Line Wings as Tracer of Molecular and Multi-phase Outflows in Infrared Bright Galaxies
Lutz, D.; Genzel, R.; Poglitsch, A. +13 more
We report a tentative correlation between the outflow characteristics derived from OH absorption at 119 µm and [C II] emission at 158 µm in a sample of 22 local and bright ultraluminous infrared galaxies (ULIRGs). For this sample, we investigate whether [C II] broad wings are a good tracer of molecular outflows, and how the two tracers…
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…