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Encyclopedia > Gamma ray burst
The image above shows the optical afterglow of gamma ray burst GRB-990123 taken on January 23, 1999. The burst is seen as a bright dot denoted by a square on the left, with an enlarged cutout on the right. The object above it with the finger-like filaments is the originating galaxy. This galaxy seems to be distorted by a collision with another galaxy.
The image above shows the optical afterglow of gamma ray burst GRB-990123 taken on January 23, 1999. The burst is seen as a bright dot denoted by a square on the left, with an enlarged cutout on the right. The object above it with the finger-like filaments is the originating galaxy. This galaxy seems to be distorted by a collision with another galaxy.
Drawing of a massive star collapsing to form a black hole. Energy released as jets along the axis of rotation forms a gamma ray burst. Credit: Nicolle Rager Fuller/NSF
Drawing of a massive star collapsing to form a black hole. Energy released as jets along the axis of rotation forms a gamma ray burst. Credit: Nicolle Rager Fuller/NSF

Gamma-ray bursts (GRBs) are the most luminous events occurring in the universe since the Big Bang. They are flashes of gamma rays emanating from seemingly random places in deep space at random times. The duration of a gamma-ray burst is typically a few seconds, but can range from a few milliseconds to minutes, and the initial burst is usually followed by a longer-lived "afterglow" emitting at longer wavelengths (X-ray, ultraviolet, optical, infrared, and radio). Gamma-ray bursts are detected by orbiting satellites about two to three times per week, but their actual rate of occurrence is much higher because not all bursts are pointed at Earth. Download high resolution version (2908x1844, 855 KB) File links The following pages link to this file: Gamma ray burst GRB 990123 Categories: Astronomy images ... Download high resolution version (2908x1844, 855 KB) File links The following pages link to this file: Gamma ray burst GRB 990123 Categories: Astronomy images ... Optical afterglow of gamma ray burst GRB-990123 (the bright dot within the white square and in the enlarged cutout) on 23 January 1999. ... is the 23rd day of the year in the Gregorian calendar. ... This article is about the year. ... Image File history File links Size of this preview: 800 × 558 pixelsFull resolution (2000 × 1396 pixel, file size: 1. ... Image File history File links Size of this preview: 800 × 558 pixelsFull resolution (2000 × 1396 pixel, file size: 1. ... This article is about the astronomical object. ... For other uses, see Black hole (disambiguation). ... This article does not cite any references or sources. ... For other uses, see Universe (disambiguation). ... For other uses, see Big Bang (disambiguation). ... This article is about electromagnetic radiation. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... For other uses, see Ultraviolet (disambiguation). ... Visible light redirects here. ... For other uses, see Infrared (disambiguation). ...


The majority of observed GRBs appear to be collimated emission caused by the collapse of the core of a rapidly rotating, high-mass star into a black hole. A subclass of GRBs (the "short" bursts) appear to originate from a different process, the leading candidate being the collision of neutron stars orbiting in a binary system. All known GRBs originate from outside our own galaxy, though a related class of phenomena, SGR flares, are associated with Galactic magnetars. The sources of most GRBs are billions of light years away. Collimated light is light whose rays are parallel. ... For other uses, see Black hole (disambiguation). ... For the Hugo Award-winning story by Larry Niven, see Neutron Star (story). ... For the band of the same name, see: Binary Star (band) Hubble image of the Sirius binary system, in which Sirius B can be clearly distinguished (lower left). ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos; or simply the Galaxy) is a barred spiral galaxy in the Local Group, and has special significance to humanity as the location of the solar system, which is located near the Orion... A soft gamma repeater is an astronomical object, now known to be a type of magnetar, which emits large bursts of gamma rays and X-rays at irregular intervals. ... Artists conception of a magnetar, with magnetic field lines A magnetar is a neutron star with an extremely powerful magnetic field, the decay of which powers the emission of copious amounts of high-energy electromagnetic radiation, particularly X-rays and gamma-rays. ... A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one year. ...


A nearby gamma ray burst could possibly cause mass extinctions on Earth.[1] Though the short duration of a gamma ray burst would limit the immediate damage to life, a nearby burst might alter atmospheric chemistry by reducing the ozone layer and generating acidic nitrogen oxides. These atmospheric changes could ultimately cause severe damage to the biosphere. An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... For other uses, see Atmosphere (disambiguation). ... For other uses, see Chemistry (disambiguation). ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen... For other uses, see Biosphere (disambiguation). ...

Contents

Discovery and history

Vela and the discovery of GRBs

Cosmic gamma-ray bursts were discovered in the late 1960s by the US Vela nuclear test detection satellites. The Velas were built to detect gamma-radiation pulses emitted by nuclear weapon tests in space. The United States suspected that the USSR might attempt to conduct secret nuclear tests after signing the Nuclear Test Ban Treaty in 1963. Any discoveries of weapon tests has never been publicly declared and details of the Vela Incident, an as-yet unidentified flash of light over the South Atlantic on September 22, 1979, remain classified. For other uses of terms redirecting here, see US (disambiguation), USA (disambiguation), and United States (disambiguation) Motto In God We Trust(since 1956) (From Many, One; Latin, traditional) Anthem The Star-Spangled Banner Capital Washington, D.C. Largest city New York City National language English (de facto)1 Demonym American... Vela was the name of a group of satellites developed as the Vela Hotel element of Project Vela by the United States to monitor compliance with the 1963 Partial Test Ban Treaty by the Soviet Union, and other nuclear-capable states. ... The Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water, often abbreviated as the Partial Test Ban Treaty (PTBT), Limited Test Ban Treaty (LTBT), or Nuclear Test Ban Treaty (NTBT), although the former also refers to the Comprehensive Test Ban Treaty (CTBT), is a treaty... Orthographic projection centered on the Prince Edward Islands, the location of the Vela incident The Vela Incident (sometimes known as the South Atlantic Flash) was an as-yet unidentified flash of light detected by a United States Vela satellite on September 22, 1979. ...


In a classic example of scientific serendipity, the satellites did detect flashes of radiation that looked nothing like a nuclear weapons signature, coming from seemingly random directions in deep space. These results were published in 1973,[2] launching the scientific study of GRBs. Look up Serendipity in Wiktionary, the free dictionary. ...


BATSE

The presence of GRBs was confirmed later by many space missions such as Apollo and the Soviet Venera probes. Many speculative theories about these events were presented, most of which involved nearby Galactic sources. There were no major advances until the 1991 launch of the Compton Gamma Ray Observatory and its Burst and Transient Source Explorer (BATSE) instrument, an extremely sensitive gamma-ray detector. This instrument provided crucial data indicating that gamma-ray bursts are isotropic,[3] and not biased towards any particular direction in space, such as the galactic plane or the Galactic center, ruling out nearly all Galactic origins. BATSE data also showed that GRBs fall into two distinct categories: short-duration, hard-spectrum bursts ("short bursts"), and long-duration, soft-spectrum bursts ("long bursts").[4] Short bursts are typically less than two seconds in duration and are dominated by higher-energy photons; long bursts are typically more than two seconds in duration and dominated by lower-energy photons. The separation is not absolute and the populations overlap observationally, but the distinction suggests two different classes of progenitors. Project Apollo was a series of human spaceflight missions undertaken by the United States of America (NASA) using the Apollo spacecraft and Saturn launch vehicle, conducted during the years 1961 – 1975. ... Venera 7 lander Color image taken from the surface of Venus by the Soviet Venera 13 lander The Venera (Russian: Венера; formerly, sometimes referred to as Venusik in the West) series of probes was developed by the USSR to gather data from Venus. ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos; or simply the Galaxy) is a barred spiral galaxy in the Local Group, and has special significance to humanity as the location of the solar system, which is located near the Orion... Illustration of CGRO The Compton Gamma Ray Observatory(CGRO) was the second of the NASA Great Observatories to be launched to space, following the Hubble Space Telescope. ... Illustration of CGRO The Compton Gamma Ray Observatory(CGRO) was the second of the NASA Great Observatories to be launched to space, following the Hubble Space Telescope. ... Isotropic means independent of direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented. ... The galactic plane is the plane in which the majority of a flattened galaxys mass lies. ... For the series of books, see Galactic Center Saga. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ...


BeppoSAX and the afterglow era

For decades after the initial discovery, no GRB had been associated with a known counterpart or host, such as a star or galaxy, due to poor resolution of gamma-ray detectors. The best hope for changing this situation seemed to be in finding a fainter, fading, longer wavelength emission following the burst itself, the "afterglow" of a GRB, as predicted by most models.[5] However, despite intensive searches, no such emission had been found. Model may refer to more than one thing : For models in society, art, fashion, and cosmetics, see; role model model (person) supermodel figure drawing modeling section In science and technology, a model (abstract) is understood as an abstract or theoretical representation of a phenomenon,see; geologic modeling model (economics) model...


This changed in 1997 when the Dutch/Italian satellite BeppoSAX detected a gamma-ray burst (GRB 970228)[6], when it pointed its X-ray camera at the direction from which the burst had originated, and detected a fading X-ray emission. Additional study from ground-based telescopes identified a fading optical counterpart as well.[7] With the location of this event precisely known, once the GRB faded, deep imaging was able to identify a faint, very distant host galaxy at the GRB location, the first of many to be localized.[8] Within only a few weeks, the long controversy about the distance scale had ended: GRBs were extragalactic events, originating inside faint galaxies[9] at enormous distance. By finally establishing the distance scale, characterizing the environments in which GRBs occur, and providing a new window on GRBs both observationally and theoretically, this discovery revolutionized the study of GRBs.[10] BeppoSAX was an Italian-Dutch satellite for X-ray astronomy. ...


Swift and GRBs today

As of 2007, a similar revolution in GRB astronomy is in progress, largely as a result of successful launch of NASA's Swift satellite in November 2004, which combines a sensitive gamma-ray detector with the ability to slew on-board X-ray and optical telescopes towards the direction of a new burst in less than a minute.[11] Swift's discoveries include the first observations of short burst afterglows and vast amount of data on the behavior of GRB afterglows at early stages during their evolution, even before the GRB's gamma-ray emission has stopped. The mission has also discovered huge X-ray flares appearing within minutes to days after the end of the GRB. The National Aeronautics and Space Administration (NASA) (IPA [ˈnæsə]) is an agency of the United States government, responsible for the nations public space program. ... The Swift Gamma-Ray Burst Mission consists of an unmanned spacecraft called Swift, which was launched into orbit on November 20, 2004, at 17:16:00 UTC (12:16 PM, EST) by a Delta 2 7320-10C expendable launch vehicle. ...


Distance scale and energetics

Galactic vs. extragalactic models

Prior to the launch of BATSE, the distance scale to GRBs was completely unknown. Theories for the location of these events ranged from the outer regions of our own solar system to the edges of the known universe. The discovery that bursts were isotropic—coming from completely random directions—narrowed down these possibilities greatly, and by the mid 1990s only two theories were considered generally viable: GRBs originate from a very large, diffuse halo (or "corona") around our own Galaxy, or that they originate from distant galaxies far beyond our local group. This article is about the Solar System. ... A member of the Local Group of galaxies, irregular galaxy Sextans A is 4. ...


Supporters of the Galactic model pointed to the class of well-known objects known as soft gamma repeaters (SGRs), highly magnetized Galactic neutron stars known to periodically erupt in bright flares at gamma-ray and other wavelengths, and stated that there may be an unobserved population of similar objects at greater distances, producing GRBs.[12] Furthermore, the sheer brightness of a typical gamma-ray burst would impose enormous requirements on the energy released in such an event if it really occurred in a distant galaxy. A soft gamma repeater is an astronomical object, now known to be a type of magnetar, which emits large bursts of gamma rays and X-rays at irregular intervals. ... This article is about the celestial body. ...


Supporters of the extragalactic model claimed that the Galactic neutron-star hypothesis involved too many ad-hoc assumptions in order to reproduce the degree of isotropy reported by BATSE and that an extragalactic model was far more natural regardless of its problems.[13]


Extragalactic nature of GRBs

The discovery of afterglow emission associated with faraway galaxies definitively supported the extragalactic hypothesis. Not only are GRBs extragalactic events, but they are also observable to the limits of the visible universe; a typical GRB has a redshift of at least 1.0 (corresponding to a distance of 8 billion light-years), while the most distant known (GRB 050904) has a redshift of 6.29 (12.3 billion light years).[14] As observers are able to acquire spectra of only a fraction of bursts - usually the brightest ones - many GRBs may actually originate from even higher redshifts. This article is about the physical phenomenon. ... GRB 050904 is the most distant gamma ray burst observed as of 2005. ...


GRB Jets: collimated emission

Many GRBs have been observed to undergo a jet break in their light curve, during which the optical afterglow quickly changes from slowly fading to rapidly fading as the jet slows down.[15] Furthermore, features suggestive of significant asymmetry have been observed in at least one nearby type Ic supernova, which may have the same progenitor stars as GRBs and have been observed to accompany GRBs in some cases (see "Progenitors"). The jet opening angle (degree of beaming), however, varies greatly, from 2 degrees to more than 20 degrees. There is some evidence which suggests that the jet angles and apparent energy released are correlated in such a way that the true energy release of a (long) GRB is approximately constant—about 1044 J, or around 1/2000 of a solar mass.[16] This is comparable to the energy released in a bright type Ib/c supernova (sometimes termed a "hypernova"). Bright hypernovae do in fact appear to accompany some GRBs.[17] In astronomy, a light curve is a graph of light intensity as a function of time. ... Type Ib and Ic supernovae are categories of stellar explosions. ... For other uses, see Supernova (disambiguation). ... For other uses, see Supernova (disambiguation). ... This article needs additional references or sources for verification. ...


The fact that GRBs are jetted also suggests that there are far more events occurring in the Universe than actually seen, even when factoring in the limited sensitivity of available detectors. Most jetted GRBs will "miss" the Earth and never be seen; only a small fraction happen to be pointed the right way to allow detection. Still, even with these considerations, the rate of GRBs is very small—about once per galaxy per 100,000 years.[18] This article is about Earth as a planet. ...


Short GRBs

The above arguments apply only to long-duration GRBs. Short GRBs, while also extragalactic, appear to come from a lower-redshift population and are less luminous than long GRBs.[19] They appear to be generally less beamed[20] or possibly not beamed,[21] intrinsically less energetic than their longer counterparts, and probably more frequent in the universe despite being observed rarely.


Progenitors: what makes GRBs explode?

Main article: Gamma ray burst progenitors

The immense distances of most gamma-ray bursts has made pinning down the nature of the system the produces these explosions extremely difficult. The currently favored model for the origin of most observed gamma-ray bursts is the collapsar model[22], in which the core of an extremely massive, low-metallicity, rapidly-rotating star collapses into a black hole, and the infall of material from the star onto the black hole powers an extremely energetic jet that blasts outward through the stellar envelope. When the jet reaches the stellar surface, a gamma-ray burst is produced. Eta Carinae, in the constellation of Carina, one of the nearer candidates for a hypernova Gamma ray burst progenitors are the types of celestial objects that can emit gamma ray bursts (GRBs). ... A collapsar is a fast-rotating Wolf-Rayet star with a massive (greater than 30 solar masses) core, which collapses to form a large, rotating black hole, drawing in the surrounding envelope of stellar matter at relativistic speeds with a Lorentz factor of around 150, making collapsars the fastest celestial...


While the collapsar model has enjoyed a great deal of success, many other models exist that are still seriously considered. Winds from highly magnetized, newly-formed neutron stars (protomagnetars)[23], accretion-induced collapse of older neutron stars[24][25], and the mergers of binary neutron stars[26] have all been proposed as alternative models. The different models are not mutually exclusive, and it is possible that different bursts have different progenitors. For example, there is now good evidence that some short gamma-ray bursts (GRBs with a duration of less than about two seconds) occur in galaxies without massive stars[19], providing strong evidence that this subset of events are associated with a different progenitor population from longer bursts - for example, merging neutron stars.


Emission mechanisms

The means by which gamma-ray bursts convert energy into radiation remains poorly understood, and as of 2007 there is still no generally accepted model for how this process occurs.[27] A successful model of GRBs must explain not only the energy source, but also the physical process for generating an emission of gamma rays which matches the durations, light spectra, and other characteristics of observed GRBs.[28] The nature of the longer-wavelength (X-ray through radio) afterglow emission that follows gamma-ray bursts has been modeled much more successfully as synchrotron emission from a relativistic shock wave propagating through interstellar space[29], but this model has had difficulty explaining the observed features of some observed GRB afterglows (particularly at early times and in the X-ray band)[30], and may be incomplete, or in some cases even inaccurate. Gamma ray burst emission mechanisms are theories that explain how the energy from a gamma ray burst progenitor (regardless of the actual nature of the progenitor) is turned into radiation. ... Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ...


Mass extinction on Earth

Research has been conducted to investigate the consequences of Earth being hit by a beam of gamma rays from a nearby (about 500 light years) gamma ray burst. This is motivated by the efforts to explain mass extinctions on Earth and estimate the probability of extraterrestrial life. A consensus seems to have been arrived at the fact that damage by a gamma ray burst would be very limited because of its very short duration, and the fact that it would only cover half the Earth, the other half being in its shadow. A sufficiently close gamma ray burst would however, result in serious damage to the atmosphere, perhaps instantly wiping out half the ozone layer, and causing nitrogen-oxygen recombination, thereby generating acidic nitrogen oxides. These effects could diffuse across to the other side of the Earth and result in long-term climate and atmospheric changes and a mass extinction. However, the damage from a gamma ray burst would probably be significantly greater than a supernova at the same distance. An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... Green people redirects here. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen... An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... For other uses, see Supernova (disambiguation). ...


The idea that a nearby gamma-ray burst could significantly affect the Earth's atmosphere and potentially cause severe damage to the biosphere was introduced in 1995 by physicist Stephen Thorsett, then at Princeton University.[31] In 2005, Scientists at NASA and the University of Kansas released a more detailed study which suggested that the Ordovician-Silurian extinction events which occured 450 million years ago could have been triggered by a gamma-ray burst. The scientists do not have direct evidence to suggest that such a burst resulted in the ancient extinction, rather the strength of their work is their atmospheric modeling, essentially a "what if" scenario. The scientists calculated that gamma-ray radiation from a relatively nearby star explosion, hitting the Earth for only ten seconds, could deplete up to half of the atmosphere's protective ozone layer, the recovery for which would take at least five years. With the ozone layer damaged, ultraviolet radiation from the Sun would kill much of the life on land and near the surface of oceans and lakes, disrupting the food chain. While gamma-ray bursts in our Milky Way galaxy are indeed rare, NASA scientists estimate that at least one nearby event has probably hit the Earth in the past billion years. Life on Earth is at least 3.5 billion years old. Dr. Bruce Lieberman, a paleontologist at the University of Kansas, originated the idea that a gamma-ray burst specifically could have caused the great Ordovician extinction. He said, "We do not know exactly when one came, but we're rather sure it did come - and left its mark. What's most surprising is that just a 10-second burst can cause years of devastating ozone damage."[32] Stephen Erik Thorsett (b. ... Princeton University is a private coeducational research university located in Princeton, New Jersey. ... The University of Kansas (often referred to as KU or just Kansas) is an institution of higher learning in Lawrence, Kansas. ... The Ordovician-Silurian extinction event, labeled End O here. ... For other uses, see Ultraviolet (disambiguation). ... For other uses, see Life (disambiguation). ... A landform comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography. ... Animated map exhibiting the worlds oceanic waters. ... For other uses, see Lake (disambiguation). ... == HEADLINE TEXT== Food chains, food webs and/or food networks describe the feeding relationships between other species to another within an ecosystem. ... For other uses, see Milky Way (disambiguation). ...


Comparative work in 2006 on galaxies in which GRBs have occurred suggests that metal-deficient galaxies are the most likely candidates. The likelihood of the metal-rich Milky Way galaxy hosting a GRB was estimated at less than 0.15%, significantly reducing the likelihood that a burst had caused mass extinction events on Earth.[33]


Notable GRBs

GRBs of significant historical or scientific importance include:

  • 670702: The first GRB ever detected.[34]
  • 970228: The first GRB with a successfully detected afterglow. The location of the afterglow was coincident with a very faint galaxy, providing strong evidence that GRBs are extragalactic.[35]
  • 970508: The first GRB with a measured redshift (distance), 0.835. This confirmed unambiguously that GRBs are extragalactic.[36]
  • 971214: In 1997, this was believed by some to be the most energetic event in the universe. This claim has since been discredited.[37][38]
  • 980425: The first GRB with an observed associated supernova (1998bw), providing strong evidence of the link between GRBs and supernovae. The GRB itself was very unusual for being extremely underluminous. Also the closest GRB to date.[39]
  • 990123: This GRB had the optically brightest afterglow measured to date, momentarily reaching or exceeding a magnitude of 8.9, which would be visible with an ordinary pair of binoculars, despite its distance of nearly 10 billion light years. This was also the first GRB for which optical emission was detected before the gamma-ray emission had ceased.[40]
  • 030329A: An extremely close (z=0.168),[41] and therefore extremely bright GRB, with an unambiguous supernova association.[42] GRB 030329 was so bright that its gamma radiation ionized the Earth's upper atmosphere.[43]
  • 050509B: The first short GRB with a host association. Provided evidence that (some) short GRBs, unlike long GRBs, occur in old galaxies and do not have accompanying supernovae.[44]
  • 050724: A thoroughly observed short gamma-ray burst with an afterglow suggesting the demise of a neutron star orbiting a black hole.[45]
  • 050904: The most distant GRB with a securely measured distance, at a redshift of 6.29 (13 billion light-years).[46]
  • 060218: A low-redshift GRB with an accompanying supernova.[47]
  • 060505: The first, well-observed, long duration GRB not accompanied by a bright supernova.[48]
  • 060614: Another recent gamma-ray burst not accompanied by an observable supernova.[49]

On February 28, 1997, BeppoSAX managed to pin down the location of an optical counterpart to a gamma ray burst, which was designated GRB 970228 in accordance with the date of the event. ... GRB 971214 is a gamma ray burst observed in 1997. ... Optical afterglow of gamma ray burst GRB-990123 (the bright dot within the white square and in the enlarged cutout) on 23 January 1999. ... Porro-prism binoculars with central focusing Binocular telescopes, or binoculars, (also known as field glasses) are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. ... GRB 050509b was a gamma ray burst observed by the NASA Swift satellite on May 9, 2005. ... For the Hugo Award-winning story by Larry Niven, see Neutron Star (story). ... GRB 050904 is the most distant gamma ray burst observed as of 2005. ... GRB 060218 was a gamma ray burst with unusual characteristics never seen before. ... GRB 060614 was a remarkable gamma ray burst (GRB) detected by the Swift satellite on June 14, 2006 with puzzling properties, which challenge current progenitor models. ...

See also

For other uses, see Supernova (disambiguation). ... A collapsar is a fast-rotating Wolf-Rayet star with a massive (greater than 30 solar masses) core, which collapses to form a large, rotating black hole, drawing in the surrounding envelope of stellar matter at relativistic speeds with a Lorentz factor of around 150, making collapsars the fastest celestial... A soft gamma repeater is an astronomical object, now known to be a type of magnetar, which emits large bursts of gamma rays and X-rays at irregular intervals. ... Gamma-ray astronomy is the astronomical study of the cosmos with gamma rays. ... Artists conception of gamma-ray burst and related phenomena. ... Projected timeline of the Suns life In astronomy, stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. ... For other uses, see Black hole (disambiguation). ...

References

  1. ^ Melott, A.L., et al. (2004). "Did a gamma-ray burst initiate the late Ordovician mass extinction?". International Journal of Astrobiology 3: 55-61. 
  2. ^ Klebesadel, R. et al. (1973). "Observations of Gamma-Ray Bursts of Cosmic Origin". Astrophysical Journal 182: L85. 
  3. ^ Meegan, C.A., et al. (1992). "Spatial distribution of gamma-ray bursts observed by BATSE". Nature 355: 143. 
  4. ^ Kouveliotou, C. et al. (1993). "Identification of two classes of gamma-ray bursts". Astrophysical Journal 413: L101. 
  5. ^ Fishman, C. J. and Meegan, C. A. (1995). "Gamma-Ray Bursts". Annual Review of Astronomy and Astrophysics 33: 415–458. 
  6. ^ GRBs are named after the date on which they are discovered: the last two digits being the year, followed by the two-digit month and two-digit day. If two or more GRBs occur on a given day, the name is appended with a letter 'A' for the first burst identified, 'B' for the second and so on.
  7. ^ van Paradijs, J., et al. (1997). "Transient optical emission from the error box of the gamma-ray burst of 28 February 1997". Nature 386: 686. 
  8. ^ Not all scientists believed this association initially, and the exact redshift of this particular galaxy was not obtained until many years later. However, the next well-localized gamma-ray burst, GRB 970508, had a firm absorption redshift of 0.835 - a distance of 7 billion light years, and unambiguously far beyond our galaxy.
  9. ^ For more on galaxies hosting GRBs, see the GHostS database http://www.grbhosts.org
  10. ^ Frontera, F. and Piro, L. (1998). Proceedings of Gamma-Ray Bursts in the Afterglow Era. Astronomy and Astrophysics Supplement Series. 
  11. ^ Gehrels, N., et al. (2004). "The Swift Gamma-Ray Burst Mission". The Astrophysical Journal 611: 1005–1020. 
  12. ^ Lamb, D. Q. (1995). "The Distance Scale to Gamma-Ray Bursts". Publications of the Astronomical Society of the Pacific 107: 1152. 
  13. ^ Paczynski, B. (1995). "How Far Away Are Gamma-Ray Bursters?". Publications of the Astronomical Society of the Pacific 107: 1167. 
  14. ^ Haislip, J., et al. (2006). "A photometric redshift of z = 6.39 ± 0.12 for GRB 050904". Nature 440 (7081): 181–183. 
  15. ^ Sari, R., Piran, T., Halpern, J. P. (1999). "Jets in Gamma-Ray Bursts". Astrophysical Journal 519: L17-L20. 
  16. ^ Frail, D.A. et al. (2001). "Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir". Astrophysical Journal 562: L55-L58. 
  17. ^ Galama, T. J. et al. (1998). "An unusual supernova in the error box of the gamma-ray burst of 25 April 1998". Nature 395: 670–672. 
  18. ^ Podsiadlowski et al. (2004). "The Rates of Hypernovae and Gamma-Ray Bursts: Implications for Their Progenitors". Astrophysical Journal 607L: 17P. 
  19. ^ a b Prochaska et al. (2006). "The Galaxy Hosts and Large-Scale Environments of Short-Hard Gamma-Ray Bursts". Astrophysical Journal 641: 989. 
  20. ^ Watson, D. et al. (2006). "Are short γ-ray bursts collimated? GRB 050709, a flare but no break". Astronomy and Astrophysics 454: L123-L126. 
  21. ^ Grupe, D. et al. (2006). "Jet Breaks in Short Gamma-Ray Bursts. I: The Uncollimated Afterglow of GRB 050724". Astrophysical Journal: In publication. 
  22. ^ MacFadyen, A. I. and Woosley, S. (1999). "Collapsars: Gamma-Ray Bursts and Explosions in "Failed Supernovae"". ApJ 524: 262-289. 
  23. ^ Metzger, B. (2007). "Proto-Neutron Star Winds, Magnetar Birth, and Gamma-Ray Bursts". AIP Conference Proceedings 937: 521-525. 
  24. ^ Vietri, M. and Stella, L. (1998). "A Gamma-Ray Burst Model with Small Baryon Contamination". ApJ 507: L45-L48. 
  25. ^ MacFadyen, A. I. (2006). "Late flares from GRBs --- Clues about the Central Engine". AIP Conference Proceedings 836: 48-53. 
  26. ^ Blinnikov, S., et al. (1984). "Exploding Neutron Stars in Close Binaries". Soviet Astronomy Letters 10: 177. 
  27. ^ Gamma-ray bursts from synchrotron self-Compton emission. blackwell-synergy.com (August 2004). Retrieved on 2007-10-12.
  28. ^ Fishman, Gerald J. (May 22, 1995). Gamma-Ray Bursts: An Overview. nasa.gov. Retrieved on 2007-10-12.
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Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 285th day of the year (286th in leap years) in the Gregorian calendar. ... is the 142nd day of the year (143rd in leap years) in the Gregorian calendar. ... Year 1995 (MCMXCV) was a common year starting on Sunday (link will display full 1995 Gregorian calendar). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 285th day of the year (286th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... is the 155th day of the year (156th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... is the 109th day of the year (110th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... is the 46th day of the year in the Gregorian calendar. ... Year 1974 (MCMLXXIV) was a common year starting on Tuesday (link will display full calendar) of the 1974 Gregorian calendar. ... The Astrophysical Journal is one of the foremost research journals devoted to recent developments, discoveries, and theories in astronomy and astrophysics. ... [[Media:Italic text]]{| style=float:right; |- | |- | |} is the 50th day of the year in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... is the 170th day of the year (171st in leap years) in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 27th day of the year in the Gregorian calendar. ... This article is about the year. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 131st day of the year (132nd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 348th day of the year (349th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 242nd day of the year (243rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 74th day of the year (75th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... is the 354th day of the year (355th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 315th day of the year (316th in leap years) in the Gregorian calendar. ...

External links

GRB Catalogs and Circulars
GRB General Information
  • Gamma-ray burst FAQ from CalTech
  • Gamma-ray burst information from NASA/Swift
GRB Mission Sites
GRB Follow-up Programs
News Articles and Media

  Results from FactBites:
 
Gamma-ray Burst Real-time Sky Map (18589 words)
No visible-light observations were made since the GRB is located in the sky too close to a bright star.\n\nA new and somewhat uncertain technique that uses the energy of the gamma rays to determine a distance found a ''pseudo redshift for this burst of z=1.3, or a distance of about 8.8 billion light years.
There was a 10-second-long burst of high-energy gamma rays (which rose quickly to a peak, stayed there for a few seconds, then faded rapidly), followed by a 20-second blast of lower-energy gamma-rays.
The burst was faint, with a flat emission (that is, constant brightness) of low-energy or ''softer'' gamma rays for 280 seconds.
Gamma-Ray Burst Physics (923 words)
Gamma-ray bursts (GRB) are sudden, intense flashes of gamma-rays which, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky.
GRBs were first reported in 1973, based on 1969-71 observations by the Vela military satellites monitoring for nuclear explosions in verification of the Nuclear Test Ban Treaty.
These afterglows in turn enabled the measurement of redshift distances, the identification of host galaxies, and the confirmation that GRB were, as suspected, at cosmological distances of the order of billions of light-years, similar to those of the most distant galaxies and quasars.
  More results at FactBites »

 
 

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