https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&feed=atom&action=historyRHESSI Catches Gamma-Ray Bursts - Revision history2024-03-29T13:15:46ZRevision history for this page on the wikiMediaWiki 1.16.0https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&diff=10723&oldid=prevSchriste at 17:22, 22 August 20182018-08-22T17:22:02Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 20 August 2012</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 20 August 2012</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|next_nugget = <del class="diffchange diffchange-inline">TBD</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|next_nugget=<ins class="diffchange diffchange-inline">{{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::183]]}}</ins></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|previous_nugget = [<del class="diffchange diffchange-inline">http</del>:<del class="diffchange diffchange-inline">//sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Dense_Loop_Flares Dense Loop Flares</del>]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|previous_nugget=<ins class="diffchange diffchange-inline">{{#ask: </ins>[<ins class="diffchange diffchange-inline">[Category</ins>:<ins class="diffchange diffchange-inline">Nugget]] [[RHESSI Nugget Index::181]</ins>]<ins class="diffchange diffchange-inline">}}</ins></div></td></tr>
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</table>Schristehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&diff=5367&oldid=prevJakubRipa: /* References */2012-08-17T03:22:26Z<p><span class="autocomment">References</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://esoads.eso.org/abs/2006A%26A...447...23H A New Definition of The Intermediate Group of Gamma-Ray Bursts]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://esoads.eso.org/abs/2006A%26A...447...23H A New Definition of The Intermediate Group of Gamma-Ray Bursts]</div></td></tr>
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<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[2] [http://esoads.eso.org/abs/<del class="diffchange diffchange-inline">2009A%26A</del>...<del class="diffchange diffchange-inline">498</del>..<del class="diffchange diffchange-inline">399R </del>Detailed Classification of Swift's Gamma-Ray Bursts]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[2] [http://esoads.eso.org/abs/<ins class="diffchange diffchange-inline">2010ApJ</ins>...<ins class="diffchange diffchange-inline">713</ins>..<ins class="diffchange diffchange-inline">552H </ins>Detailed Classification of Swift's Gamma-Ray Bursts]</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[3] [http://esoads.eso.org/abs/2009A%26A...498..399R Search for Gamma-Ray Burst Classes with the RHESSI Satellite]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[3] [http://esoads.eso.org/abs/2009A%26A...498..399R Search for Gamma-Ray Burst Classes with the RHESSI Satellite]</div></td></tr>
</table>JakubRipahttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&diff=5366&oldid=prevHhudson: some editing2012-08-16T23:33:46Z<p>some editing</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Jakub Ripa</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Jakub Ripa</div></td></tr>
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<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|publish_date = <del class="diffchange diffchange-inline">15 </del>August 2012</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|publish_date = <ins class="diffchange diffchange-inline">20 </ins>August 2012</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Dense_Loop_Flares Dense Loop Flares]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Dense_Loop_Flares Dense Loop Flares]</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Data sample and results ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Data sample and results ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The RHESSI GRB database <del class="diffchange diffchange-inline">counting </del>427 events from February 2002 to</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The RHESSI GRB database<ins class="diffchange diffchange-inline">, which contains </ins>427 events from February 2002 to</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>April 2008 was studied in order to <del class="diffchange diffchange-inline">put </del>more information on the</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>April 2008<ins class="diffchange diffchange-inline">, </ins>was studied <ins class="diffchange diffchange-inline">statistically </ins>in order to <ins class="diffchange diffchange-inline">give </ins>more information on the</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>classification scheme of GRB groups. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>classification scheme of GRB groups. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The bursts durations, spectral</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The bursts<ins class="diffchange diffchange-inline">' </ins>durations, spectral <ins class="diffchange diffchange-inline">hardnesses</ins>, peak count rates and spectral lags were analysed by</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">hardness</del>, peak<del class="diffchange diffchange-inline">-</del>count rates and spectral lags were analysed by</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">several </ins>methods <ins class="diffchange diffchange-inline">(for details, see references [3] and [4])</ins>.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">standard statistical </del>methods.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">These tests, as applied to the</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The </ins>distribution of GRB durations revealed that three <ins class="diffchange diffchange-inline">components </ins></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>distribution of GRB durations<del class="diffchange diffchange-inline">, </del>revealed that <del class="diffchange diffchange-inline">we need </del>three <del class="diffchange diffchange-inline">distinct</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">best describe the </ins>data <ins class="diffchange diffchange-inline">sample</ins>.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">functions representing three groups of </del>data.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">In addition a study based on </ins>the hardness-duration plane (Figure 2) also</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">A [http://mathworld.wolfram.com/MaximumLikelihood.html maximum-likelihood] </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">test applied to the to </del>the hardness-duration plane (Figure 2) also</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>revealed three clusters. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>revealed three clusters. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The probability that the in duration</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The probability that the in duration</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>intermediate group appears by chance is only 0.3%. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>intermediate group appears by chance is only 0.3%. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">Figure 2 shows a hardness-duration plane with RHESSI GRBs and three-component fit.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:182f2.jpg|thumb|center|500px|Figure <del class="diffchange diffchange-inline">1</del>:</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:182f2.jpg|thumb|center|500px|Figure <ins class="diffchange diffchange-inline">2</ins>:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Hardness ratio H plotted against the duration T90 for the RHESSI</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Hardness ratio H plotted against the duration T90 for the RHESSI</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>GRBs with the best maximum-likelihood fit of three bivariate lognormal</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>GRBs with the best maximum-likelihood fit of three bivariate lognormal</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Spectral lags and peak-counts were calculated for each event, if</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Spectral lags and peak-counts were calculated for each event, if</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>the signal-to-noise was high enough, and the three groups were</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>the signal-to-noise was high enough, and <ins class="diffchange diffchange-inline">then </ins>the three groups were</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>mutually compared. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>mutually compared. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The spectral lag tells how much is the low-energy</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The spectral lag tells how much is the low-energy</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>calculated from the peak of the cross-correlation function of two</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>calculated from the peak of the cross-correlation function of two</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>light curves derived at two different energy ranges. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>light curves derived at two different energy ranges. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">The Anderson-Darling</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">A statistical</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>test applied to the lags of the shortduration and long-duration</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>test applied to the lags of the shortduration and long-duration</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>pair of groups strongly supports the well-known claim that these</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>pair of groups strongly supports the well-known claim that these</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>two groups are different phenomena and confirms the older results</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>two groups are different phenomena and confirms the older results</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>obtained with the BATSE instrument. <del class="diffchange diffchange-inline">Surprisingly the results of the</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>obtained with the BATSE instrument. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">KolmogorovSmirnov tests imply </del>that the distributions of the peak-count</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Surprisingly it was found </ins>that the distributions of the peak-count</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>rates are different over all three groups. Cumulative distributions</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>rates are different over all three groups. Cumulative distributions</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>of peak-count rates for different GRB groups are shown on Figure</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>of peak-count rates for different GRB groups are shown on Figure</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>the data is a three-component fit representing three GRB classes. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>the data is a three-component fit representing three GRB classes. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The analysis of peak-count rates and spectral lags show that there are some</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The analysis of peak-count rates and spectral lags show that there are some</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>differences among these GRB classes.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>differences <ins class="diffchange diffchange-inline">in the properties of the gamma-ray flux </ins>among these GRB classes.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&diff=5362&oldid=prevHhudson at 12:13, 14 August 20122012-08-14T12:13:44Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 15 August 2012</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 15 August 2012</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = TBD</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = TBD</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/<del class="diffchange diffchange-inline">The_Slowest_Flare The Slowest Flare</del>]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/<ins class="diffchange diffchange-inline">Dense_Loop_Flares Dense Loop Flares</ins>]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>}}</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>}}</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td colspan="2" class="diff-lineno">Line 31:</td>
<td colspan="2" class="diff-lineno">Line 31:</td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Some works (see [1] and [2]) classifying GRBs based on statistical</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Some works (see [1] and [2]) classifying GRBs based on statistical</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>analysis of the observed gamma radiation and using data from the </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>analysis of the observed gamma radiation and using data from the </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[http://gammaray.msfc.nasa.gov/batse/ BATSE<del class="diffchange diffchange-inline">) </del>and</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[http://gammaray.msfc.nasa.gov/batse/ BATSE<ins class="diffchange diffchange-inline">] </ins>and</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[http://heasarc.nasa.gov/docs/swift/swiftsc.html Swift<del class="diffchange diffchange-inline">) </del>instruments</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[http://heasarc.nasa.gov/docs/swift/swiftsc.html Swift<ins class="diffchange diffchange-inline">] </ins>instruments</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>conclude that two groups may not be enough.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>conclude that two groups may not be enough.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:182f1.<del class="diffchange diffchange-inline">jpeg</del>|thumb|center|500px|Figure 1:</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:182f1.<ins class="diffchange diffchange-inline">jpg</ins>|thumb|center|500px|Figure 1:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Example of a gamma-ray burst (GRB061113) observed by RHESSI.]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Example of a gamma-ray burst (GRB061113) observed by RHESSI.]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td colspan="2" class="diff-lineno">Line 70:</td>
<td colspan="2" class="diff-lineno">Line 70:</td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>intermediate group appears by chance is only 0.3%. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>intermediate group appears by chance is only 0.3%. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:182f2.<del class="diffchange diffchange-inline">jpeg</del>|thumb|center|500px|Figure 1:</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:182f2.<ins class="diffchange diffchange-inline">jpg</ins>|thumb|center|500px|Figure 1:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Hardness ratio H plotted against the duration T90 for the RHESSI</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Hardness ratio H plotted against the duration T90 for the RHESSI</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>GRBs with the best maximum-likelihood fit of three bivariate lognormal</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>GRBs with the best maximum-likelihood fit of three bivariate lognormal</div></td></tr>
<tr><td colspan="2" class="diff-lineno">Line 97:</td>
<td colspan="2" class="diff-lineno">Line 97:</td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>3.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>3.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:182f3.<del class="diffchange diffchange-inline">jpeg</del>|thumb|center|500px|Figure 3:</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:182f3.<ins class="diffchange diffchange-inline">jpg</ins>|thumb|center|500px|Figure 3:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Cumulative distributions of peak-count rates F for the short-, intermediate-, </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Cumulative distributions of peak-count rates F for the short-, intermediate-, </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>and long-duration RHESSI bursts.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>and long-duration RHESSI bursts.</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=RHESSI_Catches_Gamma-Ray_Bursts&diff=5358&oldid=prevHhudson: 182 creation2012-08-14T12:06:36Z<p>182 creation</p>
<p><b>New page</b></p><div>{{Infobox Nugget<br />
|name = Nugget<br />
|title = Dense Loop Flares<br />
|number = 182<br />
|first_author = Jakub Ripa<br />
|second_author = <br />
|publish_date = 15 August 2012<br />
|next_nugget = TBD<br />
|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/The_Slowest_Flare The Slowest Flare]<br />
}}<br />
<br />
<br />
== Introduction ==<br />
<br />
[http://en.wikipedia.org/wiki/Gamma-ray_burst Gamma-ray bursts] (GRBs) <br />
are most powerful explosions observed in the universe and their<br />
sources may lie at distances reaching redshift <br />
[http://en.wikipedia.org/wiki/Redshift z] = 9.4. <br />
It takes an incredible 13.1 billion years for the light from such<br />
an object to get to the Earth. <br />
<br />
Originally it was found that there exist two groups of GRBs: the lengthy ones <br />
(with durations longer than about 2 s), and the short ones. <br />
The long GRBs are probably created when a massive <br />
[http://www.universetoday.com/24736/wolf-rayet-star/ Wolf-Rayet] star<br />
collapses at the end if its lifetime. <br />
In case of short GRBs their origin is less well understood, however <br />
astronomers do have a model explaining them as the violent<br />
mergers of two compact objects such as <br />
[http://imagine.gsfc.nasa.gov/docs/science/know_l1/neutron_stars.html neutron stars]. <br />
Some works (see [1] and [2]) classifying GRBs based on statistical<br />
analysis of the observed gamma radiation and using data from the <br />
[http://gammaray.msfc.nasa.gov/batse/ BATSE) and<br />
[http://heasarc.nasa.gov/docs/swift/swiftsc.html Swift) instruments<br />
conclude that two groups may not be enough.<br />
<br />
[[File:182f1.jpeg|thumb|center|500px|Figure 1:<br />
Example of a gamma-ray burst (GRB061113) observed by RHESSI.]]<br />
<br />
The RHESSI satellite was designed to study hard X-rays and gamma-rays<br />
from solar flares. <br />
However its <br />
[http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=27 germanium spectrometers] <br />
are only lightly shielded, thus making this instrument also very<br />
useful to study radiation from gamma-ray bursts coming to the<br />
detectors from any direction. <br />
An [http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=18 earlier Nugget] <br />
reported a RHESSI observation of a <br />
[http://solomon.as.utexas.edu/%7Eduncan/magnetar.html magnetar], for example.<br />
Figure 1 shows an example of a GRB observation. <br />
With a field of view of about half of the sky, RHESSI<br />
observes about one or two bursts per week (see the <br />
[http://grb.web.psi.ch/ RHESSI GRB catalog]).<br />
<br />
== Data sample and results ==<br />
<br />
The RHESSI GRB database counting 427 events from February 2002 to<br />
April 2008 was studied in order to put more information on the<br />
classification scheme of GRB groups. <br />
The bursts durations, spectral<br />
hardness, peak-count rates and spectral lags were analysed by<br />
standard statistical methods.<br />
These tests, as applied to the<br />
distribution of GRB durations, revealed that we need three distinct<br />
functions representing three groups of data.<br />
A [http://mathworld.wolfram.com/MaximumLikelihood.html maximum-likelihood] <br />
test applied to the to the hardness-duration plane (Figure 2) also<br />
revealed three clusters. <br />
The probability that the in duration<br />
intermediate group appears by chance is only 0.3%. <br />
<br />
[[File:182f2.jpeg|thumb|center|500px|Figure 1:<br />
Hardness ratio H plotted against the duration T90 for the RHESSI<br />
GRBs with the best maximum-likelihood fit of three bivariate lognormal<br />
functions. <br />
Solid and dashed curves delimit the confidence levels of the fit. <br />
The different GRB group members are denoted with<br />
different symbols.<br />
]]<br />
<br />
Spectral lags and peak-counts were calculated for each event, if<br />
the signal-to-noise was high enough, and the three groups were<br />
mutually compared. <br />
The spectral lag tells how much is the low-energy<br />
emission delayed in comparison to the high-energy one. <br />
It is<br />
calculated from the peak of the cross-correlation function of two<br />
light curves derived at two different energy ranges. <br />
The Anderson-Darling<br />
test applied to the lags of the shortduration and long-duration<br />
pair of groups strongly supports the well-known claim that these<br />
two groups are different phenomena and confirms the older results<br />
obtained with the BATSE instrument. Surprisingly the results of the<br />
KolmogorovSmirnov tests imply that the distributions of the peak-count<br />
rates are different over all three groups. Cumulative distributions<br />
of peak-count rates for different GRB groups are shown on Figure<br />
3.<br />
<br />
[[File:182f3.jpeg|thumb|center|500px|Figure 3:<br />
Cumulative distributions of peak-count rates F for the short-, intermediate-, <br />
and long-duration RHESSI bursts.<br />
]]<br />
<br />
== Conclusions ==<br />
<br />
RHESSI is capable of observing gamma-ray bursts coming from the<br />
deep universe and it has already collected more than four hundred<br />
such events. We constructed a new observational database for this<br />
satellite containing GRB durations, hardnesses, peak-count rates<br />
and spectral lags. According to the observations it follows that<br />
GRBs can be separated into short and long classes, and that the<br />
short GRBs are on average harder than the long ones. Furthermore<br />
the maximum-likielihood method reveals that a better description of <br />
the data is a three-component fit representing three GRB classes. <br />
The analysis of peak-count rates and spectral lags show that there are some<br />
differences among these GRB classes.<br />
<br />
== References ==<br />
<br />
[1] [http://esoads.eso.org/abs/2006A%26A...447...23H A New Definition of The Intermediate Group of Gamma-Ray Bursts]<br />
<br />
[2] [http://esoads.eso.org/abs/2009A%26A...498..399R Detailed Classification of Swift's Gamma-Ray Bursts]<br />
<br />
[3] [http://esoads.eso.org/abs/2009A%26A...498..399R Search for Gamma-Ray Burst Classes with the RHESSI Satellite]<br />
<br />
[4] [http://arxiv.org/abs/1206.6198 On the Spectral Lags and Peak-Counts of the Gamma-Ray Bursts Detected by the RHESSI Satellite]<br />
<br />
== Biographical note ==<br />
<br />
Jakub Ripa is currently a Postdoctoral researcher at the Institute for<br />
the Early Universe and at the Research Center of MEMS Space Telescope<br />
of Ewha Woman's University, Seoul, Korea.</div>Hhudson