Analysis of 8,804,545 electron velocity distribution functions (VDFs), observed by the $\mathit{Wind}$ spacecraft near 1 AU between January 1, 2005 and January 1, 2022, was performed to determine the spacecraft floating potential, $φ{\scriptstyle_{sc}}$. $\mathit{Wind}$ was designed to be electrostatically clean, which helps keep the magnitude of $φ{\scriptstyle_{sc}}$ small (i.e., $\sim$5--9 eV for nearly all intervals) and the potential distribution more uniform. We observed spectral enhancements of $φ{\scriptstyle_{sc}}$ at frequencies corresponding to the inverse synodic Carrington rotation period with at least three harmonics. The 2D histogram of $φ{\scriptstyle_{sc}}$ versus time also shows at least two strong peaks with a potential third, much weaker peak. These peaks vary in time with the intensity correlated with solar maximum. Thus, the spectral peaks and histogram peaks are likely due to macroscopic phenomena like coronal mass ejections (solar cycle dependence) and stream interaction regions (Carrington rotation dependence). The values of $φ{\scriptstyle_{sc}}$ are summarized herein and the resulting dataset is discussed.
We present new results of the backscattering dominated prompt emission model in which the photons generated through pair annihilation at the centre of a gamma ray burst (GRB) are backscattered through Compton scattering by an outflowing stellar cork. %We show that the produced spectral features are capable of producing spectral features that are widely observed in GRBs. Using Comptonized pair annihilation spectrum accompanied by bremsstrahlung radiation for seed photons, we show that the obtained spectra produce low energy photon index in the range $α\sim -1.95$ to $-1.1$, steeper high energy slopes $β\sim -3.5$ to $-2.4$ and spectral peak energies $\sim$ few KeV to few $10\times$ MeV. These findings are consistent with the values covered in GRB prompt phase observations.
Sumanjit Chakraborty, Sarbani Ray, Abhirup Datta
et al.
This paper presents the equatorial ionospheric response to eleven strong-to-severe geomagnetic storms that occurred during the period 2000-2005, the declining phase of the solar cycle 23. The analysis has been performed using the global ion density plots of Defense Meteorological Satellite Program (DMSP). Observations show that for about 91% of the cases, post-sunset equatorial irregularities occurred within 3h from the time of northward to southward transition of the Interplanetary Magnetic Field (IMF) clock angle, thus bringing out the importance of the role played by IMF By in the process of Prompt Penetration of Electric Field (PPEF) in addition to the IMF Bz. This is an improvement from the previously reported (Ray et al.,2015) 4h window of ESF generation from the southward IMF Bz crossing -10 nT.
Horst Fichtner, Jens Kleimann, Peter H. Yoon
et al.
Measurements made with the Voyager 1 spacecraft indicate that significant levels of compressive fluctuations exist in the inner heliosheath. Some studies have already been performed with respect to the mirror-mode instability in the downstream region close to the solar wind termination shock, and here we extend the investigation to the whole inner heliosheath. We employ quasilinear theory and results from a global magnetohydrodynamic model of the heliosphere to compute the time evolution of both the temperature anisotropy and the energy density of the corresponding magnetic fluctuations, and we demonstrate their likely presence in the inner heliosheath. Furthermore, we compute the associated, locally generated density fluctuations. The results can serve as inputs for future models of the transport of compressible turbulence in the inner heliosheath.