Search Publications
New constraints on the X-ray spectral properties of type 1 active galactic nuclei
Alexander, D. M.; Mateos, S.; Ward, M. J. +3 more
We present a detailed characterization of the X-ray spectral properties of 761 type 1 active galactic nuclei (AGN), selected from a cross-correlation of the SDSS DR5 quasar catalogue and the incremental version of the second XMM-Newton serendipitous X-ray source catalogue 2XMMi-DR2. The X-ray spectrum of each source has been fitted with models bas…
Influence of negatively charged plume grains on the structure of Enceladus' Alfvén wings: Hybrid simulations versus Cassini Magnetometer data
Dougherty, Michele K.; Saur, Joachim; Kriegel, Hendrik +5 more
We apply the hybrid simulation code AIKEF (adaptive ion kinetic electron fluid) to the interaction between Enceladus' plume and Saturn's magnetospheric plasma. For the first time, the influence of the electron-absorbing dust grains in the plume on the plasma structures and magnetic field perturbation, the Alfvén wing, is taken into account within …
Carbon chemistry in Galactic bulge planetary nebulae
Zijlstra, A. A.; Lagadec, E.; Gesicki, K. +4 more
Galactic bulge planetary nebulae show evidence of mixed chemistry with emission from both silicate dust and polycyclic aromatic hydrocarbons (PAHs). This mixed chemistry is unlikely to be related to carbon dredge-up, as third dredge-up is not expected to occur in the low-mass bulge stars. We show that the phenomenon is widespread and is seen in 30…
Arrival Time Calculation for Interplanetary Coronal Mass Ejections with Circular Fronts and Application to STEREO Observations of the 2009 February 13 Eruption
Luhmann, J. G.; Zhang, T. L.; Möstl, C. +11 more
One of the goals of the NASA Solar TErestrial RElations Observatory (STEREO) mission is to study the feasibility of forecasting the direction, arrival time, and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary C…
How Typical Are the Local Group Dwarf Galaxies?
McQuinn, Kristen B. W.; Dolphin, Andrew E.; Skillman, Evan D. +11 more
We compare the cumulative star formation histories (SFHs) of Local Group (LG) dwarf galaxies with those in the volume-limited ACS Nearby Galaxy Survey Treasury (ANGST) sample (D <~ 4 Mpc), in order to understand how typical the LG dwarf galaxies are relative to those in the nearby universe. The SFHs were derived in a uniform manner from high-qu…
Assessing black hole spin in deep Suzaku observations of Seyfert 1 AGN
Porquet, D.; Reeves, J. N.; Lobban, A. P. +2 more
We present a broad-band analysis of deep Suzaku observations of nearby Seyfert 1 active galactic nuclei (AGN): Fairall 9, MCG-6-30-15, NGC 3516, 3783 and 4051. The use of deep observations (exposures >200 ks) with high signal-to-noise ratio allows the complex spectra of these objects to be examined in full, taking into account features such as …
A new limit on Planck scale Lorentz violation from γ-ray burst polarization
Stecker, Floyd W.
Constraints on possible Lorentz invariance violation (LIV) to first order in E/ MPlanck for photons in the framework of effective field theory (EFT) are discussed, taking cosmological factors into account. Then, using the reported detection of polarized soft γ-ray emission from the γ-ray burst GRB041219a that is indicative of an absence…
How is open solar magnetic flux lost over the solar cycle?
Owens, M. J.; Crooker, N. U.; Lockwood, M.
The Sun's open magnetic field, magnetic flux dragged out into the heliosphere by the solar wind, varies by approximately a factor of 2 over the solar cycle. We consider the evolution of open solar flux in terms of a source and loss term. Open solar flux creation is likely to proceed at a rate dependent on the rate of photospheric flux emergence, w…
Discovery of the First Giant Double Radio Relic in a Galaxy Cluster Found in the Planck Sunyaev-Zel'dovich Cluster Survey: PLCK G287.0+32.9
Werner, Norbert; Ishwara-Chandra, C. H.; Joshi, Santosh +6 more
We report the discovery of large-scale diffuse non-thermal radio emission in PLCK G287.0+32.9, an exceptionally hot (T ~ 13 keV), massive, and luminous galaxy cluster, strongly detected by the Planck satellite in a recent, all-sky blind search for new clusters through Sunyaev-Zel'dovich effect. Giant Metrewave Radio Telescope 150 MHz and Very Larg…
Charge-exchange X-ray emission of M82: Kα triplets of O VII, Ne IX and Mg XI
Wang, Q. Daniel; Liu, Jiren; Mao, Shude
Starburst galaxies are primary feedback sources of mechanical energy and metals, which are generally measured from associated X-ray emission lines, assuming that they are from the thermal emission of the outflowing hot gas. Such line emission, however, can also arise from the charge-exchange X-ray emission (CXE) between highly ionized ions and neu…