Search Publications
A Direct Measurement of the Forward Shock Speed in Supernova Remnant 0509-67.5: Constraints on the Age, Ambient Density, Shock Compression Factor, and Electron-ion Temperature Equilibration
Hughes, John P.; Hovey, Luke; Eriksen, Kristoffer
Two Hubble Space Telescope narrow-band Hα images separated in time by 1.03 years are used for a proper motion measurement of the forward shock of the LMC supernova remnant 0509-67.5, the only spectroscopically confirmed LMC remnant of Ia origin. We measure a global shock speed of 6500 ± 200 km s-1 and constrain the pre-shock neutral hyd…
Constraint on noncommutative spacetime from PLANCK data
Chingangbam, Pravabati; Das, Subinoy; P. K., Joby
We constrain the energy scale of noncommutativity of spacetime using cosmic microwave background data from PLANCK. We find that PLANCK data put the lower bound on the noncommutativity energy scale to about 20 TeV, which is about a factor of 2 larger than a previous constraint that was obtained using data from WMAP, ACBAR and CBI. We further show t…
The Accreting Black Hole Swift J1753.5-0127 from Radio to Hard X-Ray
Done, Chris; Kaaret, Philip; Gandhi, Poshak +19 more
We report on multiwavelength measurements of the accreting black hole Swift J1753.5-0127 in the hard state at low luminosity (L ∼ 2.7 × 1036 erg s-1 assuming a distance of d = 3 kpc) in 2014 April. The radio emission is optically thick synchrotron, presumably from a compact jet. We take advantage of the low extinction (E(B-V)…
Dynamical analysis of galaxy cluster merger Abell 2146
Clowe, D. I.; Fabian, A. C.; McNamara, B. R. +12 more
We present a dynamical analysis of the merging galaxy cluster system Abell 2146 using spectroscopy obtained with the Gemini Multi-Object Spectrograph on the Gemini North telescope. As revealed by the Chandra X-ray Observatory, the system is undergoing a major merger and has a gas structure indicative of a recent first core passage. The system pres…
The relationship between mesoscale circulation and cloud morphology at the upper cloud level of Venus from VMC/Venus Express
Ignatiev, N. I.; Rodin, A. V.; Markiewicz, W. J. +4 more
The Venus Monitoring Camera (VMC) acquired a set of ultraviolet (UV) images during the Venus Express mission unprecedented in its duration from May 2006 to September 2013. Here we present the results of digital tracking of the cloud features in the upper cloud layer at latitudes 25-75°S using images from 257 orbits with the best spatial coverage. …
Magnetic forces associated with bursty bulk flows in Earth's magnetotail
Karlsson, Tomas; Nilsson, Hans; Hamrin, Maria +2 more
We present the first direct measurements of magnetic forces acting on bursty bulk flow plasma in the magnetotail. The magnetic forces are determined using Cluster multispacecraft measurements. We analyze 67 bursty bulk flow (BBF) events and show that the curvature part of the magnetic force is consistently positive, acting to accelerate the plasma…
Statistical altitude distribution of the auroral density cavity
Karlsson, T.; Li, B.; Marklund, G. T. +1 more
The statistical altitude distribution of auroral density cavities located between 3.0 and 6.5 RE is investigated using in situ observations from flux tubes exhibiting auroral acceleration. The locations of the observations are described using a pseudo altitude derived from the distribution of the parallel potential drop above and below …
Revisiting constraints on the (pseudo)conformal universe with Planck data
Rubtsov, G. I.; Ramazanov, S. R.
We revisit constraints on the (pseudo)conformal universe from the nonobservation of statistical anisotropy in the Planck data. The quadratic maximal likelihood estimator is applied to the Planck temperature maps at frequencies 143 and 217 GHz as well as their cross-correlation. The strongest constraint is obtained in the scenario of the (pseudo)co…
Investigation of the Progenitors of the Type Ia Supernovae Associated with the LMC Supernova Remnants 0505-67.9 and 0509-68.7
Schaefer, Bradley E.; Pagnotta, Ashley
Although Type Ia supernovae have been heavily scrutinized due to their use in making cosmological distance estimates, we are still unable to definitively identify the progenitors for the entire population. While answers have been presented for certain specific systems, a complete solution remains elusive. We present observations of two supernova r…
Photometric evidence of an intermediate-age stellar population in the inner bulge of M31
Williams, Benjamin F.; Lauer, Tod R.; Dalcanton, Julianne J. +5 more
We explore the assembly history of the M31 bulge within a projected major-axis radius of 180 arcsec (∼680 pc) by studying its stellar populations in Hubble Space Telescope Wide Field Camera 3 and Advanced Camera for Surveys observations. Colours formed by comparing near-ultraviolet versus optical bands are found to become bluer with increasing maj…