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Isocurvature perturbations and tensor mode in light of Planck and BICEP2
Takahashi, Tomo; Kawasaki, Masahiro; Sekiguchi, Toyokazu +1 more
We investigate the degeneracy of the isocurvature perturbations and the primordial gravitational waves, by using recent observations of the cosmic microwave background (CMB) reported by Planck and BICEP2 collaborations. We show that the tension in the bound on the tensor-to-scalar ratio r between Planck and BICEP2 can be resolved by introducing th…
Mid-J CO observations of Perseus B1-East 5: evidence for turbulent dissipation via low-velocity shocks
Caselli, Paola; Johnstone, Doug; Pon, Andy +2 more
Giant molecular clouds contain supersonic turbulence and magnetohydrodynamic simulations predict that this turbulence should decay rapidly. Such turbulent dissipation has the potential to create a warm (T ∼ 100 K) gas component within a molecular cloud. We present observations of the CO J = 5-4 and 6-5 transitions, taken with the Herschel Space Ob…
Excitation of Kinetic Alfvén Waves by Fast Electron Beams
Chen, L.; Wu, D. J.; Zhao, G. Q. +2 more
Energetic electron beams, which are ubiquitous in a large variety of active phenomena in space and astrophysical plasmas, are one of the most important sources that drive plasma instabilities. In this paper, taking account of the return-current effect of fast electron beams, kinetic Alfvén wave (KAW) instability driven by a fast electron beam is i…
0.94-2.42 µm Ground-based Transmission Spectra of the Hot Jupiter HD-189733b
Waldmann, I. P.; Tinetti, G.; Swain, M. R. +3 more
We present here new transmission spectra of the hot Jupiter HD-189733b using the SpeX instrument on the NASA Infrared Telescope Facility. We obtained two nights of observations where we recorded the primary transit of the planet in the J, H, and K bands simultaneously, covering a spectral range from 0.94 to 2.42 µm. We used Fourier analysis …
High Resolution X-Ray Spectroscopy of the Local Hot Gas along the 3C 273 Sightline
Fang, Taotao; Jiang, Xiaochuan
X-ray observations of highly ionized metal absorption lines at z = 0 provide critical information on the hot gas distribution in and around the Milky Way. We present a study of more than 10 yr of Chandra and XMM-Newton observations of 3C 273, one of the brightest extragalactic X-ray sources. Compared with previous works, we obtain much tighter con…
Processing OMEGA/Mars Express hyperspectral imagery from radiance-at-sensor to surface reflectance
Bakker, W. H.; van Ruitenbeek, F. J. A.; van der Werff, H. M. A. +4 more
OMEGA/Mars Express hyperspectral imagery is an excellent source of data for exploring the surface composition of the planet Mars. Compared to terrestrial hyperspectral imagery, the data are challenging to work with; scene-specific transmission models are lacking, spectral features are shallow making them difficult to detect, and field data for val…
IMF control of the location of Venusian bow shock: The effect of the magnitude of IMF component tangential to the bow shock surface
Barabash, Stas; Zhang, Tielong; Rong, Zhaojin +7 more
The interplanetary magnetic field (IMF) frozen in the solar wind, together with the solar EUV radiation, can significantly affect the location of Venusian bow shock. To recognize the IMF effect on the Venusian bow shock, we investigated 1680 bow shock crossings recorded by Venus Express during the unusually long-lasting solar minimum (May 2006 to …
Discovery of O VII line emitting gas in elliptical galaxies
Fabian, Andrew C.; Sanders, Jeremy S.; Finoguenov, Alexis +7 more
In the cores of ellipticals, clusters, and groups of galaxies, the gas has a cooling time shorter than 1 Gyr. It is possible to probe cooling flows through the detection of Fe XVII and O VII emission lines, but so far O VII has not been detected in any individual object. The Reflection Grating Spectrometers (RGS) aboard XMM-Newton are currently th…
Evidence of deflected super-Alfvénic electron jet in a reconnection region with weak guide field
Xu, Xiaojun; Yuan, Zhigang; Huang, Shiyong +4 more
Recent numerical simulations demonstrated that electron diffusion region develops into two-scale structure, i.e., the inner electron diffusion region and the outer electron diffusion region. The outer diffusion region is manifested as super-Alfvénic electron jet embedded in central current sheet. However, the electron jets are deflected from neutr…
Pre-flare Dynamics of Sunspot Groups
Korsós, M. B.; Ludmány, A.; Baranyi, T.
Several papers provide evidence that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare-producing areas, this work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead…