Spectral properties of long and short Gamma-Ray Bursts: comparison between BATSE and Fermi bursts

We compare the spectral properties of 227 Gamma Ray Bursts (GRBs) detected by the Fermi Gamma Ray Burst Monitor (GBM) up to February 2010 with those of bursts detected by the CGRO/BATSE instrument. Out of 227 Fermi GRBs, 166 have a measured peak energy E_peak_obs of their \nuF(\nu) spectrum: of these 146 and 20 belong the long and short class, respectively. Fermi long bursts follow the correlations defined by BATSE bursts between their E_peak_obs vs fluence and peak flux: as already shown for the latter ones, these correlations and their slopes do not originate from instrumental selection effects. Fermi/GBM bursts extend such correlations toward lower fluence/peak energy values with respect to BATSE ones whereas no GBM long burst with E_peak_obs exceeding a few MeV is found, despite the possibility of detecting them. Again as for BATSE, $\sim$ 5% of long and almost all short GRBs detected by Fermi/GBM are outliers of the E_peak-isotropic equivalent energy ("Amati") correlation while no outlier (neither long nor short) of the E_peak-isotropic equivalent luminosity ("Yonetoku") correlation is found. Fermi long bursts have similar typical values of E_peak_obs but a harder low energy spectral index with respect to all BATSE events, exacerbating the inconsistency with the limiting slopes of the simplest synchrotron emission models. Although the short GRBs detected by Fermi are still only a few, we confirm that their E_peak_obs is greater and the low energy spectrum is harder than those of long ones. We discuss the robustness of these results with respect to observational biases induced by the differences between the GBM and BATSE instruments.Comment: 10 pages, 8 figures, submitted to A&

A Note on Hot Springs in Southeastern Alaska

In an earlier note a survey was made of hot springs in interior Alaska which had been reported much earlier by Waring, and in this further account the coverage is extended to southeastern Alaska. Following directions recorded by Waring I attempted to reach four hot springs on Baranof Island. … Of those springs visited in southeastern Alaska, it is evident that the ones at the heads of Tenekee Inlet and Teka Bay are worthy of further study, and of inclusion into a system of land classification which would preserve them in their natural and unique state for future generations

Analysis of Plasma Bubble Signatures in the Ionosphere

Plasma bubbles are large scale structures of depleted plasma density in Earth\u27s ionosphere that disrupt radio and satellite communications, to include global navigation satellite systems. This study used the Ionospheric Forecast Model (IFM) to analyze affected look angles and total electron content (TEC) differences due to plasma bubbles of various sizes for 27 geophysical conditions consisting of different seasons and levels of solar and geomagnetic activity at 421 GPS ground stations worldwide. Overall, different geographic locations and plasma bubble configurations produced different affected look angle profiles. Bigger plasma bubbles, larger density depletion factors, higher levels of solar activity and the equinoctial months resulted in greater slant TEC differences and, hence, greater communication problems. The results of this study not only improved the accuracy of the Air Force\u27s operational ionospheric model and space weather forecasting capability, but also provided military leaders with a clear picture of the expected plasma bubble impacts to communications reliability when planning and executing military operations from the strategic to tactical level

Afterglows from precursors in Gamma Ray Bursts. Application to the optical afterglow of GRB 091024

About 15% of Gamma Ray Bursts have precursors, i.e. emission episodes preceding the main event, whose spectral and temporal properties are similar to the main emission. We propose that precursors have their own fireball, producing afterglow emission due to the dissipation of the kinetic energy via external shock. In the time lapse between the precursor and the main event, we assume that the central engine is not completely turned off, but it continues to eject relativistic material at a smaller rate, whose emission is below the background level. The precursor fireball generates a first afterglow by the interaction with the external circumburst medium. Matter injected by the central engine during the "quasi-quiescent" phase replenishes the external medium with material in relativistic motion. The fireball corresponding to the main prompt emission episode crashes with this moving material, producing a second afterglow, and finally catches up and merges with the first precursor fireball. We apply this new model to GRB 091024, an event with a precursor in the prompt light curve and two well defined bumps in the optical afterglow, obtaining an excellent agreement with the existing data.Comment: 11 pages, 6 figures, 3 tables. Accepted for publication in MNRAS, Main Journa

Ciao, Güiyermo, arrivederci!

Artículo memorativo sobre las actividades del poeta y traductor Guillermo Fernández como coordinador de talleres literarios y de traducción en Toluca, Estado de México

Lindblad dissipative dynamics in the presence of phase coexistence

We investigate the dissipative dynamics yielded by the Lindblad equation within the coexistence region around a first-order phase transition. In particular, we consider an exactly solvable, fully connected quantum Ising model with n-spin exchange (n>2) - the prototype of quantum first-order phase transitions - and several variants of the Lindblad equations. We show that physically sound results, including exotic nonequilibrium phenomena such as the Mpemba effect, can be obtained only when the Lindblad equation involves jump operators defined for each of the coexisting phases, whether stable or metastable

Debunking the Myths: International Commercial Arbitration and Section 1782(a)

International commercial arbitration continues to be the preferred dispute resolution mechanism for cross-border commercial disputes. Its popularity resides not only in the allure of efficient and flexible proceedings, but in the prospect of having highly qualified and reputable experts decide cases without the danger of national biases. Despite it being a private method of dispute resolution, international arbitration ultimately relies on an intergovernmental legal framework that allows enforcement of arbitral awards in over 150 countries in the world. Yet, arbitrators are constrained in their search for truth; they lack the coercive power to compel parties and non-parties to produce evidence that may be crucial to the outcome of the proceedings

Interspecific and Intraspecific Variation between and among Symphurus Plagiusa (Linnaeus) and Symphurus Civitatus Ginsburg with Notes on their Distribution

A thesis presented to the faculty of the School of Sciences and Mathematics at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Chester A, Nava, Jr. on December 3, 1976