Search Publications
The X-ray binary analogy to the first AGN quasi-periodic oscillation
Done, Chris; Middleton, Matthew
The narrow line Seyfert 1 galaxy REJ 1034+396 is so far unique amongst active galaxies (AGN) in showing a quasi-periodic oscillation (QPO) in its variability power spectrum. There are multiple types of QPO seen in black hole binary (BHB) systems, so we need to identify which BHB QPO corresponds to the one seen in the AGN. A key hint is the `hot di…
Mapping the interstellar medium in galaxies with Herschel/SPIRE
Elbaz, D.; Pérez-Fournon, I.; Bock, J. J. +57 more
The standard method of mapping the interstellar medium in a galaxy, by observing the molecular gas in the CO 1-0 line and the atomic gas in the 21-cm line, is largely limited with current telescopes to galaxies in the nearby universe. In this letter, we use SPIRE observations of the galaxies M 99 and M 100 to explore the alternative approach of ma…
The tidal tails of the ultrafaint globular cluster Palomar 1
Evans, N. W.; Belokurov, V.; Gieles, M. +3 more
Using the optimal filter technique applied to Sloan Digital Sky Survey photometry, we have found extended tails stretching about 1° (or several tens of half-light radii) from either side of the ultrafaint globular cluster Palomar 1. The tails contain roughly as many stars as does the cluster itself. Using deeper Hubble Space Telescope data, we see…
Star Formation in the Bullet Cluster. I. The Infrared Luminosity Function and Star Formation Rate
Gonzalez, Anthony H.; Zaritsky, Dennis; Markevitch, Maxim +2 more
The Bullet Cluster is a massive galaxy cluster at z = 0.297 undergoing a major supersonic (Mach 3) merger event. Using data from Spitzer MIPS and the Infrared Array Camera, optical imaging, and optical spectroscopy, we present the global star formation rate (SFR) of this unique cluster. Using a 90% spectroscopically complete sample of 37 star-form…
Distribution of Magnetic Bipoles on the Sun over Three Solar Cycles
Pevtsov, Alexei A.; Tlatov, Andrey G.; Vasil'eva, Valerya V.
We employ synoptic full disk longitudinal magnetograms to study latitudinal distribution and orientation (tilt) of magnetic bipoles in the course of sunspot activity during cycles 21, 22, and 23. The data set includes daily observations from the National Solar Observatory at Kitt Peak (1975-2002) and Michelson Doppler Imager on board the Solar and…
Radio and Deep Chandra Observations of the Disturbed Cool Core Cluster Abell 133
Sarazin, C. L.; Forman, W. R.; Murray, S. S. +4 more
We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of emission extending from two symmetric wing-like features. The plume is capped with a filamentary radio structure that has been previously classified as a ra…
A Study of the Build-up, Initiation, and Acceleration of 2008 April 26 Coronal Mass Ejection Observed by STEREO
Cheng, X.; Ding, M. D.; Zhang, J.
In this paper, we analyze the full evolution, from a few days prior to the eruption to the initiation, final acceleration, and propagation, of the coronal mass ejection (CME) that occurred on 2008 April 26 using the unprecedented high cadence and multi-wavelength observations by the Solar Terrestrial Relations Observatory. There existed frequent f…
Cause of super-thermal electron heating during magnetotail reconnection
Eastwood, J. P.; Lin, R. P.; Øieroset, M. +5 more
We present a candidate mechanism for the energization of super-thermal electrons during magnetic reconnection in the Earth's magnetotail. By analyzing in-situ measurements of electron distribution functions we characterize the relative energy gain of the electrons as a function of energy, Δ${\cal{E}(${\cal{E}). For all the events considered the hi…
The Galaxy-wide Distributions of Mean Electron Density in the H II Regions of M51 and NGC 4449
Beckman, John E.; Gutiérrez, Leonel
Using Advanced Camera for Surveys-Hubble Space Telescope images to yield continuum-subtracted photometric maps in Hα of the Sbc galaxy M51 and the dwarf irregular galaxy NGC 4449, we produced extensive (over 2000 regions for M51 and over 200 regions for NGC 4449) catalogs of parameters of their H II regions: their Hα luminosities, equivalent radii…
Production of High-temperature Plasmas During the Early Phases of a C9.7 Flare
Harra, Louise K.; Hara, Hirohisa; Watanabe, Tetsuya +1 more
Explosive chromospheric evaporation is predicted from some current solar flare models. In this paper, we analyze a flare with high time cadence raster scans with the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft. This observation covers an area of 240'' × 240'', with the 1'' slit in about 160 s. The early phases of a C9.7 flare tha…