Search Publications
Ultra-narrow Negative Flare Front Observed in Helium-10830 Å Using the 1.6 m New Solar Telescope
Xu, Yan; Cao, Wenda; Liu, Chang +10 more
Solar flares are sudden flashes of brightness on the Sun and are often associated with coronal mass ejections and solar energetic particles that have adverse effects on the near-Earth environment. By definition, flares are usually referred to as bright features resulting from excess emission. Using the newly commissioned 1.6 m New Solar Telescope …
Detection of Lyman-alpha Emission from a Triply Imaged z = 6.85 Galaxy behind MACS J2129.4-0741
Fontana, Adriano; Pentericci, Laura; Schmidt, Kasper B. +13 more
We report the detection of Lyα emission at ∼9538 Å in the Keck/DEIMOS and Hubble Space Telescope WFC3 G102 grism data from a triply imaged galaxy at z=6.846+/- 0.001 behind galaxy cluster MACS J2129.4-0741. Combining the emission line wavelength with broadband photometry, line ratio upper limits, and lens modeling, we rule out the scenario that th…
Effect of data gaps: comparison of different spectral analysis methods
Mursula, Kalevi; Echim, Marius; Munteanu, Costel +1 more
In this paper we investigate quantitatively the effect of data gaps for four methods of estimating the amplitude spectrum of a time series: fast Fourier transform (FFT), discrete Fourier transform (DFT), Z transform (ZTR) and the Lomb-Scargle algorithm (LST). We devise two tests: the single-large-gap test, which can probe the effect of a single da…
Estimation of bounce resonant scattering by fast magnetosonic waves
Shprits, Yuri Y.
In this study we present calculation of bounce resonant scattering of near equatorially mirroring electrons by fast magnetosonic waves. We first explore the sensitivity of the scattering rates and estimated time scales to a different number of resonances included into calculations. We then explore the sensitivity of calculated rates to the assumed…
The Impact of Accurate Extinction Measurements for X-Ray Spectral Models
Smith, Randall K.; Valencic, Lynne A.; Corrales, Lia
Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Non…
A textbook example of ram-pressure stripping in the Hydra A/A780 cluster
Rossetti, M.; Molendi, S.; De Grandi, S. +7 more
In the current epoch, one of the main mechanisms driving the growth of galaxy clusters is the continuous accretion of group-scale halos. In this process, the ram pressure applied by the hot intracluster medium on the gas content of the infalling group is responsible for stripping the gas from its dark-matter halo, which gradually leads to the viri…
The accelerated build-up of the red sequence in high-redshift galaxy clusters
Demarco, R.; Lidman, C.; Huertas-Company, M. +6 more
We analyse the evolution of the red sequence in a sample of galaxy clusters at redshifts 0.8 < z < 1.5 taken from the HAWK-I Cluster Survey (HCS). The comparison with the low-redshift (0.04 < z < 0.08) sample of the WIde-field Nearby Galaxy-cluster Survey (WINGS) and other literature results shows that the slope and intrinsic scatter o…
Magnetically Dominated Parallel Interstellar Filaments in the Infrared Dark Cloud G14.225-0.506
Zhang, Qizhou; Girart, Josep Miquel; Busquet, Gemma +2 more
The infrared dark cloud G14.225-0.506 (IRDC G14.2) displays a remarkable complex of parallel dense molecular filaments projected on the plane of the sky. Previous studies of dust emission and molecular lines have speculated whether magnetic fields could have played an important role in the formation of such elongated structures, which are hosts to…
The Search for Extraterrestrial Intelligence in Earth's Solar Transit Zone
Heller, René; Pudritz, Ralph E.
Over the past few years, astronomers have detected thousands of planets and candidate planets by observing their periodic transits in front of their host stars. A related method, called transit spectroscopy, might soon allow studies of the chemical imprints of life in extrasolar planetary atmospheres. Here, we address the reciprocal question, name…
GK Persei and EX Hydrae: Intermediate polars with small magnetospheres
Werner, K.; Ducci, L.; Doroshenko, V. +2 more
Observed hard X-ray spectra of intermediate polars are determined mainly by the accretion flow velocity at the white dwarf surface, which is normally close to the free-fall velocity. This allows us to estimate the white dwarf masses as the white dwarf mass-radius relation M - R and the expected free-fall velocities at the surface are well known. T…