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Gamma RayBursts

may be formed by CannonBall pulses of AccretingMatter in SuperNova explosions. InA CannonBallModel of Gamma-Ray Bursts: SuperLuminal Signatures(astro-ph/0008474), Dar and De Rujula say: "... A core-collapseSN results in a compact object and a fast-rotating torus ofnon-ejected fallen-back material. ... the long-duration gamma raybursts (GRBs) and their afterglows are produced by highlyrelativistic jets emitted in supernova explosions. We propose thatthe result of the event is not just a compact object plus the ejecta:within a day, a fraction of the parent star falls back to produce athick accretion disk. The subsequent accretion ...(not shown [inthe above figure]) generates jets and constitutes the GRB"engine", as in the observed ejection of relativistic "cannonballs"of plasma by microquasars and active galactic nuclei. The GRB isproduced as the jetted cannonballs exit the supernova shell reheatedby the collision, re-emitting their own radiation and boosting thelight of the shell. They decelerate by sweeping up interstellarmatter, which is accelerated to cosmic-rayenergies and emits synchrotron radiation: the afterglow. Weemphasize here a smoking-gun signature of this model of GRBs: thesuperluminal motion of the afterglow ...".

In GAMMA-RAYBURSTS AND THE SOCIOLOGY OF SCIENCE, hep-ph/0306140, Alvaro deRujula says: "... I discuss what we have learned about Gamma-RayBursts (GRBs) by studying their afterglows, and how these areinterpreted in the generally-accepted fireball model of GRBs, as wellas in the generally-unaccepted cannonball model of the samephenomena. ... Some three times a day, on average, gamma-raybursts (GRBs) reach the upper atmosphere from isotropicallydistributed sky locations. Much of their energy is in photons ofa few hundred keV, with a total fluence of 10^(-6) erg s^(-1), giveor take a couple of orders of magnitude. GRB durations range fromtens of milliseconds to hundreds of seconds, with varied timestructures generally consisting of fast rising and declining,isolated or partially-superimposed pulses. The distribution of GRBdurations is bimodal, with a trough at [about] 2 s,separating "short" from "long" GRBs ... GRBs are ahighly-beamed but relatively- small fraction of the energetic budgetof a supernova (SN) explosion. ... Our information about the oncetotally mysterious gamma-ray bursts increased spectacularly in thepast few years. The rapid directional localization of GRBs by thesatellites BeppoSAX, Rossi and by the Inter-Planetary Network ofspacecrafts led to a flurry of progress. The crucial discovery ...was the existence of "afterglows" (AGs) of long-duration GRBs: notsurprisingly, a GRB "event" does not end as the gamma-ray fluxbecomes undetectably small. The source continues to emit light at allsmaller observable frequencies, ranging from X-rays to radio waves,and to be observable for months, or even years. The fact that theseremaining emissions can be very well localized in the sky has led tothe discovery of the GRBs' host galaxies ... the measurement oftheir redshifts ... that verified their cosmological origin; theidentification of their birthplaces - mainly star formation regionsin normal galaxies - and the first evidence for a possibleassociation (in time and location) between GRBs and supernovaexplosions .... that of GRB 980425 and the supernova SN1998bw. ...The fact that the progenitors of long GRBs are core-collapse SNe,long advocated in the CB model, has received spectacular supportafter this talk was delivered ... the CB model explains well andin an extremely simple fashion practically all aspects of the data onlong-duration GRBs. ... So far, the CB model has encountered noproblems in its confrontation with data.

It is in its confrontation with humans thatthe model fares the worst. ... a ... referee ... reports: "The claimthat the CB model works better than the standard fireball models isnot made in a way that would convince any objective reader". He doesnot bother to say why. To me this sounds as being impermeable tofacts. Finally, we complain to the editor, who responds: "I have noclaim to infallibility". My colleagues and I have written some 18papers on GRBs in the CB model, the first four of which were rejectedon grounds very similar to the above. That is, not once on the basisof scientific critique. This is very discouraging. One is temptedto entitle all of one's papers on the subject "Mission Impossible".... In other realms of science theexistence of a sensible model challenging the standard lore would bevery welcome, as opposed to olympically ignored. Viki Weisskopfused to say "Physics is bestdone in a hostile environment". Surely my coauthors and I are, inthis sense, obliged to quite a few ominous and anonymous colleagues.But we would not have been able to survive the environment for long,had we not held prior tenured positions. ...".


| 920229 | 920622| 940217 | 970111 |970228 | 970508 |971214 | 990123|


Some may be at CosmologicalDistances.

Some are at SuperNovas inother Galaxies.

Some may be in our Milky WayGalaxy.

Some may be related toCETI.

Here is a discussion ofhow GRBs might cause extinctions of ( some? all? ) intelligent lifein our Galaxy.

GRBs have many interestingcharacteristics.

Gamma Rays may be related to Thunderstorms,Jets, Sprites, and Elves.

 

Gamma Ray Burstsources (GRBs) were discovered in the 1960s by U. S. and Russiansatellites searching for nuclear explosions.

(from Sky and Telescope, September 1996)

 

astro-ph/0106574,by Djorgovski, Frail, Kulkarni, Sari, Bloom, Galama, Harrison, Price,Fox, Reichart, Yost, Berger, Dierks, Goodrich, and Chaffee, is a goodsummary of the status of GRB research as of June 2001.


Some GRBs are located very near X-ray sources, opticalsources, radio sources, or distant galaxies.

 

If the distant galaxies are where the GRBs arelocated, then the GRBs must be very energetic. GRB971214is near a galaxy that is about 12 billion light years from Earthand, in the 7 May 1998 issue of Nature, Kulkarni et. al. estimatethat the distance redshift z = 3.42 implies an energy of 3x10^53 ergin gamma-rays alone, if the emission is isotropic.

(GRB 9901023 may have been even moreenergetic.)

Kulkarni et. al. sat that the most likely source of such energy isthe Pair-ElectroMagnetic Pulse(PEM Pulse) in the Dyadosphere of a Black Hole.

Remo Ruffini, Bianco, Fraschetti, and Xue, in astro-ph/0106532,say: "... Given the very accurate data from the BATSE experiment andRXTE and Chandra satellites, we use the GRB 991216 as a prototypicalcase to test the EMBH theory linking the origin of the energy of GRBsto the electromagnetic energy of black holes. The fit of theafterglow fixes the only two free parameters of the model and leadsto a new paradigm for the interpretation of the burst structure, theIBS paradigm. ... in GRBs we can distinguish an injector phase anda beam-target phase.

The injector phase includes

The injector phase terminates at the point where the plasmatransparency condition is reached and the ... proper-gamma ray burst... P-GRB is emitted.

The beam-target phase addresses the interaction of the ...afterglow ... ultra-high energy baryons ... ABM pulse, namely thebeam generated during the injection phase, with the ... interstellarmedium ... ISM as the target. It gives rise to

... It leads as well to a reconsideration of the relative roles ofthe afterglow and burst in GRBs... Such differentiation leads to anatural possible explanation of the bimodal distribution of GRBsobserved by BATSE. The agreement with the observational data inregions extending from the horizon of the EMBH all the way out to thedistant observer confirms the uniqueness of the model. ... Theintrinsic simplicity of the EMBH model of GRBs, shown here to dependonly from two parameters, offers an unique opportunity to use GRBs as"standard candles" in cosmology. ...".

 

The cosmological distance of such GRBs depends on the validity ofthe identification of the GRB with the source or galaxy that ismeasured, usually by redshift, to be distant.

 

 

GRB 970228:

On 28 February 1997, the Beppo-SAX satellite observed a GRBand an X-ray source near the position of the GRB. Within a day,Paradijs, Groot, and Galama made an image of that part of the sky,using telescopes at the Canary Islands. Eight days later, they made asecond image, and found that one point of light had faded. On 13March 1997, they looked at the faded object (Optical Transient) withESO's 3.5 meter telescope at La Silla, Chile, and found a small dimgalaxy (Extended Soutce). If in fact the galaxy is the X-ray source,and if in fact the X-ray source is the GRB, then it would beestablished that the GRB is in a distant galaxy, at cosmologicaldistances. An article about the observations of Paradijs et. al. isin Science 275 (21 March1997) 1738. A HubbbleSpace Telescope press release on 16 September 1997 describedobservations made on 5 September 1997 of the Optical Transient andExtended Source, stating:

"1. The continued visibility of the [Optical Transientidentified with the burst], and the rate of its decline overtime, support theories that the light comes from a gamma-ray burst ina "relativistic" fireball (expanding at the speed of light) locatedat extragalactic distances. A burst in our galaxy, at the observedbrightness, would have been slowed by the interstellar medium withinthe first few weeks, and faded from sight by now.

2. The observations contradict earlier claims [such at thosestated in Caraveo,Mignani, Tavani, and Bignami, and in Skyand Telescope weekly news bulletin of 19 April 1997] that thegamma-ray burst is moving against the sky background [propermotion]. Had proper modtion been detected, the gamma-ray burstwould have had to be no further away than about 30,000 light-years,or about the distance to the center of the galaxy.

3. The fuzzy companion object the fireball is embedded in [theExtendedSource] - as first confirmed by Hubble in March 26observations - has not noticeably faded. This means it is not arelatively nearby nebula produced by the explosion, but in alllikelihoos a host galaxy.

4. Since the burst did not occur at the center of the host galaxy,but near its edge, the gamma-ray burst phenomenon is not related toactivity in the nucleus of a galaxy. The Hubble observations supportthe "fireball" model for a gamma-ray burst.

These observations are consistent with colliding neutron starscreating the fireball, but do not require it. "

A DISTANCE that is NOT DEPENDENT on IDENTIFICATION of a GRB withan OPTICAL SOURCE MUST come from OBSERVATION of the GAMMA RAYSTHEMSELVES. In astro-ph/9705128,Hurley et. al. attempt to calculate a lower bound on the distanceof the 28 February 1997 GRB by looking at the arrival times of thesignal at different satellites (Ulysses and SAX). They compare thosetime differences with the time differences due to plane-wave arrivaltimes from the direction of the GRB. If the GRB source has aspherical curved wave-front, then you can determine the distance tothe GRB source. They find that the wave-front is consistent with aplane wave (infinite distance) and at least has radius of curvaturegreater than 11,000 AU. However, their method does not apply if a GRBsource does not produce a spherical curved wave-front..

Francisco J. Castander and D. Q. Lamb, in astro-ph/ 9803324 (30Mar 1998), The Galactic Extinction Toward GRB 970228 and ItsImplications, say: " The IRAS 100 micron image of the GRB 970228field shows that the amount of galactic dust in this direction issubstantial ... if the extended source in the burst error circleis extragalactic and therefore lies beyond the dust in our owngalaxy, its optical spectrum is very blue: its observed color ... isconsistent only with a starburst galaxy, an irregular galaxy at z>1:5, or a spiral galaxy at z >2. On the other hand, itsobserved color and surface brightness ... are similar to thoseexpected for the reflected light from a dust cloud in our own galaxy,if the cloud lies in front of most of the dust in thisdirection."

GRB 970508:

Observations of another GRB on 8-10 May 1997 were reportedby Sky andTelescope in its weekly news bulletin of 16 May 1997 and in IAUCircular 6655. "On May 8th BeppoSAX pinpointed a gamma-ray burst inthe far-northern constellation Camelopardalis.Within hours, Howard E.Bond (Space Telescope Science Institute) imaged the burst's environswith the Kitt Peak 36-inch reflector. Returning to the field the nextnight, he found that one starlike point had brightened by about 1magnitude (a 2.5-fold increase). Subsequent observations byresearchers worldwide found that the variable "star" peaked aroundMay 10th at 20th magnitude and has since faded.The variable lies atthe same position as the GRB to the accuracy with which this can bedetermined --about one arcminute. ... Caltech astronomers[obtained] a decent spectrum with the Keck II telescope onMauna Kea. This spectrum shows the fingerprint of interveningmaterial, which has selectively absorbed light of certainwavelengths. The absorptions appear to be caused by iron andmagnesium ions, but at wavelengths stretched nearly twofold by theexpansion of space. This suggests that the burst took place at adistance of several billion light-years. ... According to ChryssaKouveliotou (Universities Space Research Association) and hercolleagues, if the gamma rays seen on May 8th really do lie at thedistance of the light-absorbing material, the outburst produced 6 x10^50 ergs each second at its brightest. This is comparable to theamount of energy our Sun has emitted over the last 5 billion years --making the energy-producing mechanism of [cosmologicallydistant] GRBs more mysterious than ever."

Twinkling fluctuations were seen in the radio counterpart of the 8May 1997 GRB. According to the Skyand Telescope weekly news bulletin of 19 Sepember 1997:":Astronomers have a new clue to the nature of gamma-ray bursts,mysterious eruptions of high-energy radiation that pop off about oncea day at random points on the sky. Earlier this year, on May 8th, onesuch burst was recorded not only by orbiting gamma-ray detectors, butalso by the BeppoSAX X-ray satellite, which pinpointed the burst'slocation on the celestial sphere almost instantly. Ground-basedoptical telescopes swung into action and found a previously unknownsource of visible light at the position of the gamma-ray event. Thissoon faded, but not before astronomers were able to deduce that itwas billions of light-years away, well outside our own galaxy. Radiotelescopes observed a counterpart too, and over several weeks thissource fluctuated in intensity like a twinkling star. Unlike visibletwinkling, which is caused by irregularities in Earth's atmosphere,radio twinkling is caused by irregularities in the gas cloudspervading the Milky Way. Just as planets don't twinkle due to theirfinite angular size, so too should radio sources not twinkle if theyare sufficiently large. As Shri Kulkarni (Caltech) and Dail Frail(National Radio Astronomy Observatory) report in Nature this week,the radio source coincident with the May 8th gamma-ray burst did stoptwinkling after awhile, suggesting that the source of the radioemission had grown in angular size. From their detailed studies,Kulkarni and Frail deduce that the fireball must have expanded to adiameter of at least a tenth of a light-year since the eruption lastMay, implying that debris is flying outward at least 85 percent ofthe speed of light. This means the burst itself must have beenoutrageously energetic -- perhaps resulting from the collision of twoneutron stars in a distant galaxy, or even the collision of two blackholes." Further details are in astro-ph/9709199by Waxman, Kulkarni, and Frail.

GRB990123:

Blandford andHelfand, in astro-ph/9902004, say "... The recent gamma rayburst, GRB 990123 has a redshift zs = 1:61 and appears to have anenergy E = 3 x 10^54 erg, and a peak luminosity Lmax = 10^53 erg/sec... assuming isotropic emission. This is ten times larger thanhitherto reported and in excess of the rest mass of a solar massobject. Optical observations have revealed an intervening galaxy withredshift zd = 0:286 displaced from the line of sight by 1.8 +/- 0.4".This raises the possibility that the burst is enhanced bygravitational lensing. We argue that multiple images are not presentwithin the burst profile or within 15 minutes of the burst trigger.Preliminary inspection of the intervening galaxy image allows us toset a limit on the magnification of M < 60; if subsequent analysisof Ulysses data extends this window to about 1 day, and/or if afainter burst is not observed within a few weeks, the magnificationis at most modest (M < 10), and the burst remains the mostintrinsically luminous event yet observed. ...".

Fenimore,Ramirez-Ruiz, and Wu, in astro-ph/9902007, say "... GRB990123 wasa long complex gamma-ray burst with an optical transient that startedearly within the gamma-ray phase ... . The peak and power law decayof the early optical emission strongly indicates the presence of adecelerating relativistic shell during that phase. Prior to thisburst, it was not known if the shell decelerated during the burst, soan external shock origin for the gamma rays was still possible. Ifthe gamma-rays are produced in the external shock, then the pulsewidths should reflect the observed deceleration of the shell andincrease by about 2.3. We analyze the fine time structure observed inthe gamma-ray data from BATSE and determine that the width of thepeaks do not increase as expected for a decelerating shell; the laterpulses are, at most, a factor of 1.15 longer than the earlier pulses.We also analyze the variability to determine what fraction of theshell's surface could be involved in the production of the gammarays, the so-called surface filling factor. For GRB990123 we find afilling factor of 0.008. The lack of pulse width evolution eliminatesthe only remaining kinematically acceptable external shockexplanation for the gamma-ray phase and, thus, the gamma rays mustoriginate at a central engine. ...".

 

If some of the Gamma Ray Bursts are atcosmological distances, they may be CETI messagesfrom Life in our Universe near the time of itsBig Bang. or slightly later times such as the time of massivestar formation in Starburst Galaxies.

Such Life could be of any of theThree Types of Life, or a combination of them.

 


Some GRBs may be LOCAL:

Cline, Matthey,and Otwinowski, in their Study of Very Short Gamma-Ray Bursts,"... carried out a detailed study of the morphology of gamma-raybursts (GRBs) with time duration less than 100 ms ...[they] show that these bursts are very different from therest of the GRB events. The short bursts appear to be nearlyidentical, suggesting a separate class of GRBs .. [and] ...show that the short bursts have a Euclidean space-time distribution... that implies that these sources are likely. ... local orGalactic ... ".

Link andEpstein say that high luminosity GRBs have a slight excess nearthe plane of our Galaxy and toward its center. IfGRBs are local CETI phenomena for communication withother stars in our Galaxy, then it would be expected that, asLink andEpstein found, low luminosity GRBs for communication with nearbystars would be distributed isotropically, while high luminosity GRBsfor communication with distant stars would have the slight excessnear the plane of our Galaxy and toward its center.

GRB 970111:

No radio, optical, or X-ray counterpart was observed for thebright gamma-ray burster GRB970111. In astro-ph/9704180,Frail, Kulkarni,Costa, Frontera, Heise, Feroci, Piro, Dal Fiume, Nicastro, Palazzi,and Jager report on a comprehensive radio monitoring program ofthe bright gamma-ray burster GRB970111. These VLA observationswere made at a frequency of 1.4 GHz and span a range of post-bursttimescales between 28 hours and one month. Despite extensive samplingat sub-milliJansky sensitivities, no radio source was detected above0.5 mJy in the current best error box (~14 arcmin^2) for GRB970111. Ahighly unusual radio source, VLA J1528.7+1945, was seen to drop influx density by a factor of two in our monitoring period but it liesoutside the error box and thus it is unlikely to be related toGRB970111. Cosmological fireball models of gamma-ray bursts makepredictions of late-time emission occurring at longer wavelengths.The absence of a flaring or fading radio counterpart to GRB970111provides strong constraints on these models.

 

Further, Scharf,Jahoda, and Boldt, in their paper astro-ph/9506008, On theMeasurement of a Cosmological Dipole in the Photon Number Countsof Gamma-Rays Bursts, conclude that

"... the fluence and number weighted dipoles are inconsistent forthe null hypothesis [that GRBs track the cosmological CMBdistribution] at roughly the 2-sigma level.

"... the correlation with the direction of motion of the LocalGroup is more significant ...

"... Together these results could indicate that a non-negligiblefraction of gamma-ray bursts originate within the local (anisotropic)universe.

"There is no evidence of correlation with the direction expectedin a halo model."

Although Scharf,Jahoda, and Boldt would like to analyze a catalogue of 10,000bursts rather than the 410 they used, and they do not rule outdistance scales intermediate between galactic halo and cosmologicaldistances, their results support consideration of the hypothesis thatsome of the GRBs are relatively local, in the solar neighborhood at adistance about 1000 AU, roughly the distance of an inner Oort cloudof comets.

 

In A Burst ofSpeculation, Katz discusses collisions among comets in the Oortcloud. Gamma ray production by sonoluminescencein the water formed from cometary ice in colliding comets may befeasible.

 

Ti-Pei Li discusses a HeliosphericOrigin of Gamma-Ray Bursts, due to large-voltage andhigh-temperature pinch plasma columns produced by disruptiveelectrical discharges in the heliosphere.

In this figure from Sky and Telescope (June 1997 p. 102), thetermination shock region is the region whose geometry is most likethe distribution of GRBs, as the heliopause, hydrogen wall, and bowshock regions are asymmetrical with respect to the direction movementof the Sun through the interstellar medium. The distance scales areprobably on the order of 100 AU, but are not known for certain sincePioneer and Voyagerspacecraft have not reached the boundaries of the regions.

 


Link andEpstein say that high luminosity GRBs have a slight excess nearthe plane of our Galaxy and toward its center. If GRBs are local CETIphenomena for communication with other stars in our Galaxy, then itwould be expected that, as Linkand Epstein found, low luminosity GRBs for communication withnearby stars would be distributed isotropically, while highluminosity GRBs for communication with distant stars would have theslight excess near the plane of our Galaxy and toward itscenter.

In GammaRay Bursts and CETI, I discuss the possibility that GRBs could beCommunication by Extra-Terrestrial Intelligences using gamma-raylaser signals focussed by THE SUN AS A GRAVITATIONAL LENS:

In this gif, the distance is measured in units of Neptunes'sorbital radius, which is about 30 AU. (see Sky & Telescope, Nov.1983, p. 387)

The focal length of the sun as a gravitational lens is about 540AU, or 18 times Neptune's orbit radius. Any beam of electromagneticradiation (whether light, radio waves, or gamma rays) hitting the sunfrom about 540 AU or farther out is focussed by the sun'sgravitational field into a beam that could be used forcommunication.

ENERGETICS OF CETI GRAVITATIONAL LENS GRBs:

If they were spherically symmetric sources, GRBs located 100light-hours (720 AU) from the sun would radiate about 10^(26)erg.

However, if the ETI were beaming the gamma rays in the directionof the sun, confining the beam to about 10^(-4) steradian, the earthwould still be in the beam and the required energy would be about10^(21) erg.

For comparison, about 10^(21) erg is roughly

the energy of fission of 1 kg of U^(235),

or of the annihilation of 1 gm of matter by antimatter.

The result would be a GALACTIC GAMMA-RAY LASER CETI INTERNET:


The gif below shows the sun as a node of a CETI net made up of thesun and 4 hypothetical tetrahedral neighbor nodes. The relativistictime axis is represented by color (blue = present at the sun, red =past at the 4 neighbors). An N-star network would be represented byan (N-1)-dimensional simplex, or an Indra's Net of N jewels.

"If we could but see it, this is what every star in the galaxylooks like, sort of a sea urchin if you will, a star making images ofevery other star, starting at the minimum distance and going out toinfinity. The casting of very high-resolution images of the wholeuniverse on the sky - and these images are in focus at all distances- is a really remarkable thing."

(Drake discussing the ideas of Eshleman in The Search forExtraterrestrial Intellingence, by McDonough, Wiley (1987))

 

If some of the GammaRay Bursts are at cosmological distances, they may be messagesfrom Life in our Universe near the time of itsBig Bang, or slightly later times such as the time of massivestar formation in Starburst Galaxies.

Such Life could be of any of theThree Types of Life, or a combination of them.

 

Maybe we will discover a GRB CETI Communications Network if wecarry out the exploration program suggested by RobinCorbet in his paper The Use of Gamma-ray Bursts as Direction andTime Markers in SETI Strategies, astro-ph/9904268, in whichhe says:

"When transmitting a signal over a large distance it is more efficient to send a brief beamed signal than a continuous omni-directional transmission but this requires that the receiver knows where and when to look for the transmission. ... gamma-ray bursts may well the best "synchronizers" of all currently known phenomena due to their large intrinsic luminosities, high occurrence rate, isotropic sky distribution, large distance from the Galaxy, short duration, and easy detectability. ...".

 

 

For Classical Shannon Information Theory,Lachmann, Newman, and Moore, in cond-mat/9907500,say:

"... It has been well-known since the pioneering work of Claude Shannon in the 1940s that a message transmitted with optimal efficiency over a channel of limited bandwidth is indistinguishable from random noise to a receiver who is unfamiliar with the language in which the message is written.

In this letter we demonstrate an equivalent result about electromagnetic transmissions.

We show that when electromagnetic radiation is used as the transmission medium, the most information-efficient format for a given message is indistinguishable from black-body radiation to a receiver who is unfamiliar with that format. The characteristic temperature of the radiation is set by the amount of energy used to make the transmission.

If information is not encoded in the direction of the radiation, but only its timing, energy or polarization, then the most efficient format has the form of a one-dimensional black-body spectrum

which is easily distinguished from the three-dimensional case. ...

... For the case where the transverse momentum of photons is not used to encode information, or for broadcast transmissions, the spectrum is indistinguishable from that of a one-dimensional black body. We have also shown that the characteristic temperature of the message is simply related to the energy used to send it, and we have derived an upper limit on the rate at which information can be transmitted in both cases. ...

... we speculate that results similar to those presented here may apply to transmissions using other radiative media as well. Since many natural processes maximize the Gibbs-Boltzmann entropy, they should give rise to spectra indistinguishable from optimally efficient transmissions. For instance, if we had a transmitter that can emit any type of particle (rather than just photons), it seems plausible that the optimal spectrum of particle types and energies would be that of Hawking black-hole radiation...".

 


SOME FURTHER INTERESTING OBSERVATIONS:

GRB920229:

In astro-ph/9810270,Schaefer and Walker say: "The Gamma Ray Burst GRB920229has four extreme and unprecedented properties; a rise in brightnesswith an e-folding time scale of 220 +/- 30 microsec, a fall inbrightness with an e-folding time scale of 400 +/- 100 microsec, alarge change in spectral shape over a time of 768 microsec, and asharp spectral cutoff to high energies with delta E / E = 18%. Therapid changes occur during a spike in the light curve which was seen0.164 sec after the start of the burst. The spectrum has a peak nuF_nu at 200 keV with no significant flux above 239 keV, although thecutoff energy shifts to less than 100 keV during the decay of thespike. ..."

 

In astro-ph/9810271,Walker and Schaefer say: "... We have shown that the majority ofGRBs have flickering with rise times faster than four milliseconds,while individual flares can vary with rise times as fast as 220microseconds. ..."

 

In astro-ph/9710064,Cohen, Piran and Narayan show that observed data is best modeledby an intrinsic lower energy cut-off at 120 keV and that there is anobservational bias agains detecting bursts with hardness energy over500 keV by current detectors. Therefore, they suggest that a largepopulation of unobserved hard gamma-ray bursts may exist.

 

GRB920622:

In Thegamma-ray burst GB 920622, Greiner, Sommer, Bade, Fishman, Hanlon,Hurley, Kippen, Kouveliotou, Preece, Ryan, Schonfelder, Williams,Winkler, Boer, and Niel show that

"... Unlike the single instrument spectra, the composite spectrumof GB 920622 averaged over the total burst duration ranging from 20keV up to 10 MeV cannot be fit by a single power law. Instead, thespectrum shows continuous curvature across the full energy range.

"... A high temperature (about 100 KeV or higher) blackbody modeldoes not fit at all.

"... no quiescent X-ray counterpart candidate for GB 920622 hasbeen found."

 

GRB940217:

In a letter to Nature (372 (15 Dec 95) 616, 652) Hurley et. al.describe a burst on 17 Feb 94 that lasted 90 minutes and contained atleast one 18 GeV photon.

 

BATSE, on 27 Oct 96 and 29 Oct 96, detected 4 GRBs from the same part of the sky. The 27 Oct GRBs were at UT times 42,247 sec and 43,322 sec, and locations RA 67.4 and 68.7, DEC -42.4 and -54.3, with durations 100 sec and 0.9 sec. The 29 Oct GRBs were at UT times 23,677 sec and 24,350 sec, and locations RA 59.4 and 59.8, DEC -52.6 and -48.9, with durations 30 sec and 750 sec. The uncertainties in position of the 4 GRBs were 5.6, 5.8, 4.6, and 0.3 degrees, respectively.  

 

Gamma Ray Bursts (and other things) are discussed on RobertJ. Nemiroff's home page and in hisrecent papers.

Robert Forward hasdescribed StarGates for Information carried by Gamma Rays built fromSuperHeavy Ring-Shaped Nuclei.


BATSE has detected 12 gamma-ray flashes from earth. For 7 of them,concurrent weather images were obtained, and all 7 seem to be relatedto thunderstorms (Skyand Telescope, Jan 95, p. 14, and Fishman et. al., Science (27 May94) 1250, 1313).

Some thunderstorms extend to 10miles altitude, and have

blue jets at altitudes from 10 to 30 miles,

red sprites at altitudes from 30 to 60 miles,

and circular elves at altitudes from 60 to 70 miles,

as illustrated and described in the July 1997 issue of Discovermagazine:

 

 

that shows lightning below theblue jets.  

 

In a webarticle for Scientific American Explorations, W. Wayt Gibbs inSan Francisco writes:

"The ancients imagined thunderstorms and lightning to be evidence of titanic war among the gods in the sky above. ... one can indeed find wonders: ... exotic stabs of illumination called sprites and elves. ...

... it wasn't until 1994 that a team out of the University of Alaska at Fairbanks, circling around midwestern thunderstorms in a jet aircraft, obtained the first color images of sprites. These snapshots show that sprites are colorful (usually red), quite enormous and often surprisingly delicate in form. Some sprites stretch upward 95 kilometers (58 miles) from the cloudtops. They always seem to appear just as a lightning bolt--usually an especially fierce one--strikes down toward earth, and they almost always appear in groups.

Investigators now think sprites probably occur when an unusually potent stroke of lightning creates an intense electrostatic field above the cloud from which it emanates. Ions (electrically charged atoms) and electrons floating about the atmosphere are heated by this field and glow red in response, scientists speculate. ...

When researchers pointed their cameras to pick up sprites, they were surprised to discover that other bizarre light shows also illuminate the high altitudes. Vast blue jets, rising from clouds at 300 times the speed of sound in air, form cones of light that stand 40 kilometers tall. ...

Blue jets may be formed when such conditions happen to occur just as a cosmic ray (an extremely fast moving particle kicked out of a supernova or some other energetic cosmic event) collides with an air molecule in that region. The collision produces a shower of fast electrons; the upward-pointing electrostatic field above the cloud can accelerate these electrons further, to energies at which they emit blue light. ...

... a group of Stanford University researchers, led by Umran Inan of Stanford University, reported at the American Geophysical Union meeting in San Francisco that they had clocked yet another form of stratospheric lightning, one that, paradoxical though it may seem, propagates faster than the speed of light. These halos of red light, dubbed elves, were first conclusively recorded by Japanese scientists in 1995. But little was known about their structure and movement until Inan's group imaged the phenomenon with The Fly's Eye--a custom-built instrument that chains together 12 highly sensitive photodetectors, each in its own 45-centimeter (18-inch) barrel and each pointing to a different part of the sky.

The Stanford researchers managed to get a good look at 10 elves. All started just above a groundstroke of normal lightning but expanded into rings up to 300 kilometers (200 miles) across in less than a thousandth of a second. Although the elves appear to spread faster than light, analysis of the physics behind elves demonstrates that no particles actually move that fast, so Einsteinian relativity is not violated. The faster-than-light illusion seems to be caused by successively distant air molecules lighting up in rapid-fire sequence, like the strobe lights running along an airport runway.

Inan and Yuri Taranenko of Los Alamos National Laboratory have developed mathematical models which they think may explain what causes elves. According to their simulation, the key is the electromagnetic pulse produced by lightning strokes. This pulse expands like a balloon, upward and away from the groundstroke. If the pulse is strong enough, the theory goes, it energizes the ions and free electrons at the border between the stratosphere and ionosphere enough to make the charged particles shine red.

So, although the electromagnetic pulse expands at exactly the speed of light, Inan explains, the ring of shining particles formed at the lower edge of the ionosphere grows faster--just as a balloon released underwater will, as it breaks the surface, create a ripple that moves much faster outward than the rate at which the balloon rises upward. Zeus himself might be impressed.".

Lightning

According to an article by Nicola Jones on page 18 of the 8February 2003 issue of the NewScientist:

"... Just before a flash of lightning ... a huge blast of X-rays or other high-energy particles is released. ... In 31 of 37 [lightning] strikes ... [in a field in Florida] a short burst of energetic radiation ...[was observed]... lasting 10 to 100 microseconds, just before the flash. The huge amount of energy - more than 10,000 electronvolts per particle - ...[means that]... anyone standing close to a lightning strike will get a ... dose of X-rays, of about the same energy as an X-ray at the dentist. ... One way X-rays could be generated is if electrons were being ripped away from air molecules and accelerated close to the speed of light. Such "runaway electrons" are seen in fusion experiments. But researchers did not expect to see them in lightning, where the surrounding air should act to slow the electrons. ...".

John Gilman, in his paper Ball Lightning and PlasmaCohesion, physics/0302063,says:

"...The phenomenon of ball lightning has been observed for a long time, but the nature of these luminous balls has been unknown. It is proposed here that they consist of highy excited Rydberg atoms with large polarizabilities that bind them together. Thus the cohesion of the balls comes from photon exchange forces (London dispersion forces) rather than the more usual electron exchange (chemical) forces. ...

... Laboratory microwave plasmas persist for 200 ms. ...

... The cohesion in plasmas generated at the back faces of detonating explosives has a similar basis. ... the plasmas have enough cohesion to turn sharp corners (180 deg.) when guided by glass tubing; indicating that the plasma has little shear stiffness.... the plasmas persist long enough to travel in air for a few meters (of order microseconds). ...

... The lifetimes of lightning balls may be ... 10-100 seconds ... Since lightning balls are observed to travel horizontally for considerable distances, and they are translucent, their densities must be comparable with that of air ... They have been reported to pass through openings smaller than themselves ... The observed diameters of ball lightning spheres ... range from 0.02 to 1.5 m. with an average of 0.25 m. Take 0.2 m. as typical, or a radius of 10 cm. This corresponds to the maximum possible Rydberg orbital, rR ... the average rR is about 3 cm. At this radius the binding energy of an electron to its positive ion is very small, but the polarizabilty ...[ 4 pi rR^3 / 3 ]... of the average Rydberg atom is very large. ...".

 

Using laser beams to control lightning on earth is beingdone by Kawasaki, Shindo, Diels and Xin MiaoZhao:

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