Search Publications
1ES 1927+654: a bare Seyfert 2
Fabian, A. C.; Cackett, E. M.; Panessa, F. +3 more
1ES 1927+654 is an active galactic nucleus (AGN) that appears to defy the unification model. It exhibits a type-2 optical spectrum, but possesses little X-ray obscuration. XMM-Newton and Suzaku observations obtained in 2011 are used to study the X-ray properties of 1ES 1927+654. The spectral energy distribution derived from simultaneous optical-to…
Photometric Calibration of the LASCO-C2 Coronagraph over 14 Years (1996 - 2009)
Llebaria, A.; Lamy, P.; Gardès, B.
We present a photometric calibration of the SOHO/LASCO-C2 coronagraph based on the analysis of all stars down to magnitude V=8 that transited its field of view during the past 14 years of operation (1996 - 2009), extending the previous work of Llebaria, Lamy, and Danjard (Icarus182, 281, 2006). The pre-processing of the images incorporates the mos…
X-ray emission from the ultramassive black hole candidate NGC 1277: implications and speculations on its origin.
Fabian, A. C.; Miller, J. M.; Sanders, J. S. +2 more
We study the X-ray emission from NGC 1277, a galaxy in the core of the Perseus cluster, for which van den Bosch et al. have recently claimed the presence of an ultramassive black hole (UMBH) of mass 1.7× 10^{10}{ M_{{⊙}}}, unless the initial mass function of the stars in the stellar bulge is extremely bottom heavy. The X-rays originate in a power-…
The NGC 1614 interacting galaxy. Molecular gas feeding a "ring of fire"
Gallagher, J. S.; Aalto, S.; König, S. +2 more
Minor mergers frequently occur between giant and gas-rich low-mass galaxies and can provide significant amounts of interstellar matter to refuel star formation and power active galactic nuclei (AGN) in the giant systems. Major starbursts and/or AGN result when fresh gas is transported and compressed in the central regions of the giant galaxy. This…
Plasma particle simulations of wake formation behind a spacecraft with thin wire booms
Miyake, Y.; Usui, H.; Cully, C. M. +1 more
Double-probe electric field sensors installed on scientific spacecraft are often deployed using wire booms with radii much less than typical Debye lengths of magnetospheric plasmas (millimeters compared to tens of meters). However, in tenuous and cold-streaming plasmas seen in the polar cap and lobe regions, the wire booms, electrically grounded a…
Post-Eruption Arcades and Interplanetary Coronal Mass Ejections
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +1 more
We compare the temporal and spatial properties of posteruption arcades (PEAs) associated with coronal mass ejections (CMEs) at the Sun that end up as magnetic cloud (MC) and non-MC events in the solar wind. We investigate the length, width, area, tilt angle, and formation time of the PEAs associated with 22 MC and 29 non-MC events and we find no d…
An X-ray-UV correlation in Cen X-4 during quiescence
Degenaar, N.; Wijnands, R.; Miller, J. M. +3 more
Quiescent emission from the neutron star low-mass X-ray binary Cen X-4 is seen to be variable on time-scales from hundreds of seconds to years, suggesting that at least in this object, low-level accretion is important during quiescence. Here, we present results from recent XMM-Newton and Swift observations of Cen X-4, where the X-ray flux (0.5-10 …
Profiles of electron temperature and Bz along Earth's magnetotail
Petrukovich, A. A.; Zelenyi, L. M.; Nakamura, R. +1 more
We study the electron temperature distribution and the structure of the current sheet along the magnetotail using simultaneous observations from THEMIS spacecraft. We perform a statistical study of 40 crossings of the current sheet when the three spacecraft THB, THC, and THD were distributed along the tail in the vicinity of midnight with coordina…
How does star formation proceed in the circumnuclear starburst ring of NGC 6951?
Hunt, L. K.; Schinnerer, E.; Emsellem, E. +3 more
Gas inflowing along stellar bars is often stalled at the location of circumnuclear rings, which form an effective reservoir for massive star formation and thus shape the central regions of galaxies. However, how exactly star formation proceeds within these circumnuclear starburst rings is the subject of debate. Two main scenarios for this process …
The occulting galaxy pair UGC 3995. Dust properties from HST and CALIFA data
Holwerda, B. W.; Keel, W. C.
UGC 3995 is an interacting and occulting galaxy pair. UGC 3995B is a foreground face-on spiral and UGC 3995A a bright background spiral with an AGN. We present analysis of the dust in the disc of UGC 3995B based on archival Hubble Space Telescope (HST) WFPC2 and PPAK IFU data from the CALIFA survey's first data release. From the HST F606W image, w…