Search Publications
An active state of the BL Lacertae object Markarian 421 detected by INTEGRAL in April 2013
Maraschi, L.; Pian, E.; Villata, M. +22 more
Aims: Multiwavelength variability of blazars offers indirect, but very effective, insight into their powerful engines and on the mechanisms through which energy is propagated from the centre down the jet. The BL Lac object Mkn 421 is a TeV emitter, a bright blazar at all wavelengths, and therefore an excellent target for variability studies. …
Electron density inside Enceladus plume inferred from plasma oscillations excited by dust impacts
Gurnett, D. A.; Kurth, W. S.; Wahlund, J. -E. +4 more
Enceladus' southern plume is one of the major discoveries of the Cassini mission. The water neutrals and water ice particles (dust) ejected by the cryovolcanic activity populate Saturn's E ring and the neutral torus, and they interact with the plasma environment of Saturn's magnetosphere. The plasma neutrality inside Enceladus' plume has been show…
The X-Ray Spectrum of the Cooling-flow Quasar H1821+643: A Massive Black Hole Feeding Off the Intracluster Medium
Fabian, Andrew C.; Babul, Arif; Reynolds, Christopher S. +4 more
We present a deep Suzaku observation of H1821+643, an extremely rare example of a powerful quasar hosted by the central massive galaxy of a rich cooling-core cluster of galaxies. Informed by previous Chandra studies of the cluster, we achieve a spectral separation of emission from the active galactic nucleus (AGN) and the intracluster medium (ICM)…
Swift/BAT Detection of Hard X-Rays from Tycho's Supernova Remnant: Evidence for Titanium-44
Troja, E.; Cusumano, G.; Gehrels, N. +6 more
We report Swift/Burst Alert Telescope survey observations of the Tycho's supernova remnant, performed over a period of 104 months since the mission's launch. The remnant is detected with high significance (>10σ) below 50 keV. We detect significant hard X-ray emission in the 60-85 keV band, above the continuum level predicted by a simple synchro…
Increases in plasma sheet temperature with solar wind driving during substorm growth phases
Jackman, C. M.; Dandouras, I.; Fazakerley, A. N. +10 more
During substorm growth phases, magnetic reconnection at the magnetopause extracts ~1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phase…
Joint XMM-Newton and Chandra Observations of the NGC 1407/1400 Complex: A Tail of an Early-Type Galaxy and a Tale of a Nearby Merging Group
Gu, Liyi; White, Raymond E., III; Su, Yuanyuan +1 more
The nearby group centered on its bright central galaxy NGC 1407 has been suggested by previous kinematic studies to be an unusually dark system. It is also known for hosting a bright galaxy, NGC 1400, with a large radial velocity (1200 km s-1) with respect to the group center. Previous ROSAT X-ray observations revealed an extended regio…
X-ray observation of ULAS J1120+0641, the most distant quasar at z = 7.08
Salvaterra, R.; Moretti, A.; Vignali, C. +6 more
We probe the emission mechanism of the accreting super massive black holes in the high redshift Universe and, to do this, we study the X-ray spectrum of ULAS1120+064, the highest redshift quasar detected so far at z = 7.085, which has been deeply observed (340 ks) by XMM-Newton. Despite the long integration time, the spectral analysis is limited b…
Subsidence-induced methane clouds in Titan's winter polar stratosphere and upper troposphere
Barnes, J. W.; Flasar, F. M.; Achterberg, R. K. +2 more
Titan's atmospheric methane most likely originates from lakes at the surface and subsurface reservoirs. Accordingly, it has been commonly assumed that Titan's tropopause region, where the vertical temperature profile is a minimum, acts as a cold trap for convecting methane, leading to the expectation that the formation of methane clouds in Titan's…
The tilt of primordial gravitational waves spectra from BICEP2
Cheng, Cheng; Huang, Qing-Guo
In this paper we constrain the tilt of the spectrum of primordial gravitational waves from Background Imaging of Cosmic Extragalactic Polarization (BICEP2) data only. We find r = 0.21-0.10+0.04 and nt = -0.06-0.23+0.25 (at 68% C.L.) which implies that a scale-invariant primordial gravitational…
The physical nature of the 8 o'clock arc based on near-IR IFU spectroscopy with SINFONI
Vegetti, S.; Allam, S.; Brinchmann, J. +3 more
We present an analysis of near-infrared integral field unit spectroscopy of the 8 o'clock arc, a gravitationally lensed Lyman break galaxy, taken with SINFONI. We explore the shape of the spatially resolved Hβ profile and demonstrate that we can decompose it into three components that partially overlap (spatially) but are distinguishable when we i…