Swift and Fermi observations of X-ray flares: the case of Late Internal Shock

Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than ten decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi during the first three years of Fermi operations. While bright in the X-ray band, X-ray flares are often undetected at lower (optical), and higher (MeV to GeV) energies. We show that this disfavors synchrotron self-Compton processes as origin of the observed X-ray emission. We compare the broadband properties of X-ray flares with the standard late internal shock model, and find that, in this scenario, X-ray flares can be produced by a late-time relativistic (Gamma>50) outflow at radii R~10^13-10^14 cm. This conclusion holds only if the variability timescale is significantly shorter than the observed flare duration, and implies that X-ray flares can directly probe the activity of the GRB central engine.Comment: 13 pages, 4 figures, accepted for publication in Ap

Right-to-Work Laws as Economic Freedom: Their Role in Influencing the Geographic Pattern of Manufacturing Jobs, Incomes, and Finances

A large empirical literature has found positive effects from economic freedom on economic outcomes, such as output and per capita economic growth. This study seeks to explain empirically the disparate timing of state manufacturing earnings and employment decline, as well as the shift among states in both manufacturing earnings and manufacturing employment resulting from right-to-work laws, which can be viewed as reflecting labor market freedom and thereby acting as a de facto economic policy. The results of the empirical estimations suggest a marked geographic shift of manufacturing employment and compensation in the U.S. during the 1970 to 2012 time period. The empirical estimations indicate that the regions of the country that have historically represented the manufacturing base have suffered the greatest relative losses in both employment and compensation during this period. In addition to regional location, it appears that right-to-work laws have had the effect of leveling manufacturing employment and compensation levels across the states since 1970. The data analysis suggests that, at least in part due to right-to-work laws, the manufacturing sectors of the states and regions are becoming increasingly similar over time, i.e., manufacturing activity that was once highly concentrated in the Great Lakes, Northeast, and Mideast has now converged significantly, with the outcome that there is little geographic difference in concentration among the eight BEA regions

Breakdown of Kolmogorov scaling in models of cluster aggregation with deposition

The steady state of the model of cluster aggregation with deposition is characterized by a constant flux of mass directed from small masses towards large masses. It can therefore be studied using phenomenological theories of turbulence, such as Kolmogorov's 1941 theory. On the other hand, the large scale behavior of the aggregation model in dimensions lower than or equal to two is governed by a perturbative fixed point of the renormalization group flow, which enables an analytic study of the scaling properties of correlation functions in the steady state. In this paper, we show that the correlation functions have multifractal scaling, which violates linear Kolmogorov scaling. The analytical results are verified by Monte Carlo simulations.Comment: 5 pages 4 figure

Superlong GRBs

We searched for anomalously long GRBs (GRBs) in the archival records of the Burst and Transient Sources Experiment (BATSE). Ten obvious superlong (>500 s) GRBs with almost continuous emission episodes were found. Nine of these events are known from the BATSE catalog, but five have no duration estimates; we found one burst for the first time. We also detected events with emission episodes separated by a long period of silence (up to 1000 s) with a total duration of 1000--2000 s. In the latter case, we cannot reach an unequivocal conclusion about a common origin of the episodes due to the BATSE poor angular resolution. However, for most of these pairs, the probability of a coincidence of independent GRBs is much lower than unity, and the probability that all of these are coincidences is 10E-8. All of the events have a hardness ratio (the ratio of the count rates in different energy channels) typical of GRBs, and their unique duration is unlikely to be related to their high redshifts. Superlong bursts do not differ in their properties from typical long (>2 s) GRBs. We estimated the fraction of superlong GRBs (>500 s) among the long GRBs in the BATSE sample with fluxes up to 0.1 ph cm^{-2} s^{-1} to be between 0.3 and 0.5%, which is higher than the estimate based on the BATSE catalog.Comment: 11 pages, 4 figures, 3 tables, translation is made by Astronomy Letter

CE19012

In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. For a period in the 1970s and1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989. Since 2004 the survey has been fixed in October and carried out onboard the RV Celtic Explorer. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complemented since 2004 by detailed hydrographic, marine mammal and seabird surveys

Implications of the Visible and X-Ray Counterparts to GRB970228

The gamma-ray burst source GRB970228 has been observed after a delay of 8--12 hours in X-rays and after one day in visible and near infrared light. This marks the first detection of emission at lower frequencies following the gamma-ray observation of a GRB and the first detection of any visible counterpart to a GRB. We consider possible delayed visible and X-ray emission mechanisms, and conclude that the intrinsic gamma-ray activity continued at a much reduced intensity for at least a day. There are hints of such continued activity in other GRB, and future observations can decide if this is true of GRB in general. The observed multi-band spectrum of GRB970228 agrees with the predictions of relativistic shock theory when the flux is integrated over a time longer than that required for a radiating electron to lose its energy.Comment: 5 pp., tex, 1 figur

Stationary Kolmogorov Solutions of the Smoluchowski Aggregation Equation with a Source Term

In this paper we show how the method of Zakharov transformations may be used to analyze the stationary solutions of the Smoluchowski aggregation equation for arbitrary homogeneous kernel. The resulting massdistributions are of Kolmogorov type in the sense that they carry a constant flux of mass from small masses to large. We derive a ``locality criterion'', expressed in terms of the asymptotic properties of the kernel, that must be satisfied in order for the Kolmogorov spectrum to be an admissiblesolution. Whether a given kernel leads to a gelation transition or not can be determined by computing the mass capacity of the Kolmogorov spectrum. As an example, we compute the exact stationary state for the family of kernels,$K_\zeta(m_1,m_2)=(m_1m_2)^{\zeta/2}$ which includes both gelling and non-gelling cases, reproducing the known solution in the case $\zeta=0$. Surprisingly, the Kolmogorov constant is the same for all kernels in this family.Comment: This article is an expanded version of a talk given at IHP workshop "Dynamics, Growth and Singularities of Continuous Media", Paris July 2003. Updated 01/04/04. Revised version with additional discussion, references added, several typographical errors corrected. Revised version accepted for publication by Phys. Rev.

Analysis of Sub-threshold Short Gamma-ray Bursts in Fermi GBM Data

The Fermi Gamma-ray Burst Monitor (GBM) is currently the most prolific detector of Gamma-Ray Bursts (GRBs). Recently the detection rate of short GRBs (SGRBs) has been dramatically increased through the use of ground-based searches that analyze GBM continuous time tagged event (CTTE) data. Here we examine the efficiency of a method developed to search CTTE data for sub-threshold transient events in temporal coincidence with LIGO/Virgo compact binary coalescence triggers. This targeted search operates by coherently combining data from all 14 GBM detectors by taking into account the complex spatial and energy dependent response of each detector. We use the method to examine a sample of SGRBs that were independently detected by the Burst Alert Telescope on board the Neil Gehrels Swift Observatory, but which were too intrinsically weak or viewed with unfavorable instrument geometry to initiate an on-board trigger of GBM. We find that the search can successfully recover a majority of the BAT detected sample in the CTTE data. We show that the targeted search of CTTE data will be crucial in increasing the GBM sensitivity, and hence the gamma-ray horizon, to weak events such as GRB 170817A. We also examine the properties of the GBM signal possibly associated with the LIGO detection of GW150914 and show that it is consistent with the observed properties of other sub-threshold SGRBs in our sample. We find that the targeted search is capable of recovering true astrophysical signals as weak as the signal associated with GW150914 in the untriggered data.Comment: 10 pages, 9 figures, 1 table, submitted to Ap

Right-to-Work Laws as Economic Freedom: Their Role in Influencing the Geographic Pattern of Manufacturing Jobs, Incomes, and Finances

A large empirical literature has found positive effects from economic freedom on economic outcomes, such as output and per capita economic growth. This study seeks to explain empirically the disparate timing of state manufacturing earnings and employment decline, as well as the shift among states in both manufacturing earnings and manufacturing employment resulting from right-to-work laws, which can be viewed as reflecting labor market freedom and thereby acting as a de facto economic policy. The results of the empirical estimations suggest a marked geographic shift of manufacturing employment and compensation in the U.S. during the 1970 to 2012 time period. The empirical estimations indicate that the regions of the country that have historically represented the manufacturing base have suffered the greatest relative losses in both employment and compensation during this period. In addition to regional location, it appears that right-to-work laws have had the effect of leveling manufacturing employment and compensation levels across the states since 1970. The data analysis suggests that, at least in part due to right-to-work laws, the manufacturing sectors of the states and regions are becoming increasingly similar over time, i.e., manufacturing activity that was once highly concentrated in the Great Lakes, Northeast, and Mideast has now converged significantly, with the outcome that there is little geographic difference in concentration among the eight BEA regions