Triggers:GRBs - Revision history

Jure.Japelj at 09:34, 8 September 2011

2011-09-08T09:34:28Z

Jure.Japelj at 10:18, 15 July 2011

2011-07-15T10:18:30Z

Jure.Japelj at 10:14, 15 July 2011

2011-07-15T10:14:24Z

Jure.Japelj at 10:13, 15 July 2011

2011-07-15T10:13:42Z

Jure.Japelj: /* Simulation references */

2011-04-05T13:14:06Z

Simulation references

Jure.Japelj: /* Simulation references */

2011-04-05T13:13:28Z

Simulation references

Jure.Japelj: /* Simulation references */

2011-04-05T13:10:53Z

Simulation references

Jure.Japelj: /* Simulation references */

2011-04-05T13:10:30Z

Simulation references

Jure.Japelj at 12:07, 5 April 2011

2011-04-05T12:07:44Z

Jure.Japelj at 12:06, 5 April 2011

2011-04-05T12:06:59Z

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 [[File:GRB-schematic_lightcurve.png|350px|border|right]]
-Gamma-ray bursts (GRBs) are extremely energetic, brief and unpredictable explosions occuring on cosmological distances. They represent the most luminous events in the gamma-ray part of the electromagnetic spectrum known in the universe. Often, the prompt gamma-ray emission is followed by an afterglow emitted at longer wavelengths (from X-rays to radio), which can last for several days. Comprehensive review on GRBs and their physics can be found in [http://adsabs.harvard.edu/abs/2004RvMP...76.1143P Piran 2004] or [http://adsabs.harvard.edu/abs/2006RPPh...69.2259M Meszaros 2006].
+Gamma-ray bursts (GRBs) are extremely energetic, brief and unpredictable explosions occurring on cosmological distances. They represent the most luminous events in the gamma-ray part of the electromagnetic spectrum known in the universe. Often, the prompt gamma-ray emission is followed by an afterglow emitted at longer wavelengths (from X-rays to radio), which can last for several days. Comprehensive review on GRBs and their physics can be found in [http://adsabs.harvard.edu/abs/2004RvMP...76.1143P Piran 2004] or [http://adsabs.harvard.edu/abs/2006RPPh...69.2259M Meszaros 2006].
-GRB explosions are believed to be collimated, rather than spherical [http://adsabs.harvard.edu/abs/2007RMxAC..27..140G Granot 2007]. Thus the material, ejected by the explosion, is expanding in the form of a bimodal jet, characterized by an initial half-opening angle [[File:theta.png]]. The shape of the lightcurve depends on the relative position of the observer's line-of-sight and the axis of the jet cone. We can describe that with an angle [[File:thetaobs.png]] between both directions. We talk about an on-axis GRB and a 'regular' optical afterglow when [[File:theta1.png]]. In the case of [[File:theta2.png]], we can not observe the prompt gamma-ray emission. Due to the beaming effect, we could still observe the so called orphan afterglow (details in [http://adsabs.harvard.edu/abs/2007RMxAC..27..140G Granot 2007] or ). A schematic afterglow lightcurves for different jet half-opening angles and viewing angles are shown in figure on the right.
+GRB explosions are believed to be collimated, rather than spherical [http://adsabs.harvard.edu/abs/2007RMxAC..27..140G Granot 2007]. Thus the material, ejected by the explosion, is expanding in the form of a bimodal jet, characterized by an initial half-opening angle [[File:theta.png]]. The shape of the light curve depends on the relative position of the observer's line-of-sight and the axis of the jet cone. We can describe that with an angle [[File:thetaobs.png]] between both directions. We talk about an on-axis GRB and a 'regular' optical afterglow when [[File:theta1.png]]. In the case of [[File:theta2.png]], we can not observe the prompt gamma-ray emission. Due to the beaming effect, we could still observe the so called orphan afterglow (details in [http://adsabs.harvard.edu/abs/2007RMxAC..27..140G Granot 2007] or ). A schematic afterglow light curves for different jet half-opening angles and viewing angles are shown in figure on the right.
-[[File:kann.png|thumb|350px|border|left|A large sample of regular (on-axis) optical afterglow lightcurves, corrected for Galactic extinction [http://adsabs.harvard.edu/abs/2010ApJ...720.1513K  Kann et al. 2010].]]
+[[File:kann.png|thumb|350px|border|left|A large sample of regular (on-axis) optical afterglow light curves, corrected for Galactic extinction [http://adsabs.harvard.edu/abs/2010ApJ...720.1513K  Kann et al. 2010].]]
-A large sample of observed optical lightcurves of regular 'on-axis' afterglows is shown in figure on the left ([http://adsabs.harvard.edu/abs/2010ApJ...720.1513K Kann et al. 2010]).
+A large sample of observed optical light curves of regular 'on-axis' afterglows is shown in figure on the left ([http://adsabs.harvard.edu/abs/2010ApJ...720.1513K Kann et al. 2010]).
 Observations made by the Swift satellite imply that there are approximately 300 on-axis GRBs per year for which we could observe an optical afterglow.
@@ Line 25: / Line 25: @@
 [[File:F6.png|thumb|400px|border|right|Distribution of magnitudes, which are associated with detected afterglows (black), same magnitudes at the time of the first detection (grey) and magnitudes of afterglows detected by the second telescope (red) in the case of on-axis simulation. The results are given for a time of five years.]]
-In order to predict the number of optical afterglow detections with Gaia in five years of it's time of operation, a simulation was performed. The simulation took into account a scanning law of Gaia, it's field of view, etc. It consists of two parts: one for regular 'on-axis' afterglows and the other for orphan afterglows. In the former the observational data were used to constrain the parameters needed in the simulation (i.e. initial afterglow magnitude distribution, number of afterglows occuring in five years, etc.), while in the latter the parameters were obtained from theoretical predictions. Details on the simulation are given in [[#Simulation references|simulation references]].
+In order to predict the number of optical afterglow detections with Gaia in five years of it's time of operation, a simulation was performed. The simulation took into account a scanning law of Gaia, it's field of view, etc. It consists of two parts: one for regular 'on-axis' afterglows and the other for orphan afterglows. In the former the observational data were used to constrain the parameters needed in the simulation (i.e. initial afterglow magnitude distribution, number of afterglows occurring in five years, etc.), while in the latter the parameters were obtained from theoretical predictions. Details on the simulation are given in [[#Simulation references|simulation references]].
 Number of detections in respect to limiting magnitude are shown on the the right in the top figure for the case of on-axis and orphan afterglows. The average GRB orphan-afterglow detection rate has been simulated for two different circumburst environments.
@@ Line 33: / Line 33: @@
 Since GRB afterglows are initially rapidly fading and they will be observed for 4.4 seconds by each CCD camera, the change of magnitude in that time could in principle be observable. For all detected afterglows in our simulations, we therefore calculated the change of magnitude in 4.4 s, corresponding to observations by two successive CCDs, and also for observations lasting as long as a specific afterglow is in the telescope's field of view. The distribution of the change of magnitude for both cases is shown in the bottom figure on the left. Since the expected photometric error of Gaia at $M_{\rm lim} = 20$ mag will be 10 mmag at best (though it will be smaller for brighter sources [http://www.rssd.esa.int/index.php?project=GAIA&page=index ESA]), the chances of observing the change in magnitudes will be small.
-To summarize: the number of expected GRB optical afterglow detections with Gaia satellite during it's five years of expected operation is of the order of a few tens. Most of the expected detections are of the orphan afterglows, while the possibility of an on-axis afterglow detection is small (less than 10). The problem of afterglow recognition and poor time sampling of the lightcurve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
+To summarize: the number of expected GRB optical afterglow detections with Gaia satellite during it's five years of expected operation is of the order of a few tens. Most of the expected detections are of the orphan afterglows, while the possibility of an on-axis afterglow detection is small (less than 10). The problem of afterglow recognition and poor time sampling of the light curve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
-[[File:F10.png|thumb|400px|border|center|Left: Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change of magnitude in the time in which an afterglow is in the entire field of view (red) for the on-axis case. Right: Distribution of the change in magnitude in the time in which an orphan afterglow is in the field of view. Black distribution corresponds to detection after the peak in a lightcurve while red distribution corresponds to detection before the peak.]]
+[[File:F10.png|thumb|400px|border|center|Left: Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change of magnitude in the time in which an afterglow is in the entire field of view (red) for the on-axis case. Right: Distribution of the change in magnitude in the time in which an orphan afterglow is in the field of view. Black distribution corresponds to detection after the peak in a light curve while red distribution corresponds to detection before the peak.]]
 == Simulation references ==

@@ Line 29: / Line 29: @@
 Number of detections in respect to limiting magnitude are shown on the the right in the top figure for the case of on-axis and orphan afterglows. The average GRB orphan-afterglow detection rate has been simulated for two different circumburst environments.
-Bottom, left figure shows initial magnitude distribution of detected on-axis afterglows (black), same distribution at the time of the first detection (gray) and the distribution of detections with the second telescope. Similar plot for orphan afterglows is given in [[#Simulation references|references]].
+Bottom, right figure shows initial magnitude distribution of detected on-axis afterglows (black), same distribution at the time of the first detection (gray) and the distribution of detections with the second telescope. Similar plot for orphan afterglows is given in [[#Simulation references|references]].
-Since GRB afterglows are initially rapidly fading and they will be observed for 4.4 seconds by each CCD camera, the change of magnitude in that time could in principle be observable. For all detected afterglows in our simulations, we therefore calculated the change of magnitude in 4.4 s, corresponding to observations by two successive CCDs, and also for observations lasting as long as a specific afterglow is in the telescope's field of view. The distribution of the change of magnitude for both cases is shown in the bottom figure on the right. Since the expected photometric error of Gaia at $M_{\rm lim} = 20$ mag will be 10 mmag at best (though it will be smaller for brighter sources [http://www.rssd.esa.int/index.php?project=GAIA&page=index ESA]), the chances of observing the change in magnitudes will be small.
+Since GRB afterglows are initially rapidly fading and they will be observed for 4.4 seconds by each CCD camera, the change of magnitude in that time could in principle be observable. For all detected afterglows in our simulations, we therefore calculated the change of magnitude in 4.4 s, corresponding to observations by two successive CCDs, and also for observations lasting as long as a specific afterglow is in the telescope's field of view. The distribution of the change of magnitude for both cases is shown in the bottom figure on the left. Since the expected photometric error of Gaia at $M_{\rm lim} = 20$ mag will be 10 mmag at best (though it will be smaller for brighter sources [http://www.rssd.esa.int/index.php?project=GAIA&page=index ESA]), the chances of observing the change in magnitudes will be small.
 To summarize: the number of expected GRB optical afterglow detections with Gaia satellite during it's five years of expected operation is of the order of a few tens. Most of the expected detections are of the orphan afterglows, while the possibility of an on-axis afterglow detection is small (less than 10). The problem of afterglow recognition and poor time sampling of the lightcurve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
@@ Line 44: / Line 44: @@
-[[User:Jure.Japelj|Jure Japelj]] 18:09, 31 March 2011 (UTC)
+[[User:Jure.Japelj|Jure.Japelj]] 11:18, 15 July 2011 (BST)

@@ Line 21: / Line 21: @@
 == Detecting GRBs with Gaia ==
-[[File:F5.jpg|thumb|400px|border|right|GRB on-axis and OAs detection rate in five years of Gaia's operation as a function of limiting magnitudes. In the case of OAs, the results are given for two different circumburst environments.]]
+[[File:F5.png|thumb|400px|border|right|GRB on-axis and OAs detection rate in five years of Gaia's operation as a function of limiting magnitudes. In the case of OAs, the results are given for two different circumburst environments.]]
-[[File:F6.jpg|thumb|400px|border|right|Distribution of magnitudes, which are associated with detected afterglows (black), same magnitudes at the time of the first detection (grey) and magnitudes of afterglows detected by the second telescope (red) in the case of on-axis simulation. The results are given for a time of five years.]]
+[[File:F6.png|thumb|400px|border|right|Distribution of magnitudes, which are associated with detected afterglows (black), same magnitudes at the time of the first detection (grey) and magnitudes of afterglows detected by the second telescope (red) in the case of on-axis simulation. The results are given for a time of five years.]]
 In order to predict the number of optical afterglow detections with Gaia in five years of it's time of operation, a simulation was performed. The simulation took into account a scanning law of Gaia, it's field of view, etc. It consists of two parts: one for regular 'on-axis' afterglows and the other for orphan afterglows. In the former the observational data were used to constrain the parameters needed in the simulation (i.e. initial afterglow magnitude distribution, number of afterglows occuring in five years, etc.), while in the latter the parameters were obtained from theoretical predictions. Details on the simulation are given in [[#Simulation references|simulation references]].
@@ Line 35: / Line 35: @@
 To summarize: the number of expected GRB optical afterglow detections with Gaia satellite during it's five years of expected operation is of the order of a few tens. Most of the expected detections are of the orphan afterglows, while the possibility of an on-axis afterglow detection is small (less than 10). The problem of afterglow recognition and poor time sampling of the lightcurve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
-[[File:F10.jpg|thumb|400px|border|center|Left: Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change of magnitude in the time in which an afterglow is in the entire field of view (red) for the on-axis case. Right: Distribution of the change in magnitude in the time in which an orphan afterglow is in the field of view. Black distribution corresponds to detection after the peak in a lightcurve while red distribution corresponds to detection before the peak.]]
+[[File:F10.png|thumb|400px|border|center|Left: Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change of magnitude in the time in which an afterglow is in the entire field of view (red) for the on-axis case. Right: Distribution of the change in magnitude in the time in which an orphan afterglow is in the field of view. Black distribution corresponds to detection after the peak in a lightcurve while red distribution corresponds to detection before the peak.]]
 == Simulation references ==

@@ Line 21: / Line 21: @@
 == Detecting GRBs with Gaia ==
-[[File:F1.jpg|thumb|400px|border|right|The average GRB on-axis afterglow detection rate in respect to limiting magnitude in five years.]]
+[[File:F5.jpg|thumb|400px|border|right|GRB on-axis and OAs detection rate in five years of Gaia's operation as a function of limiting magnitudes. In the case of OAs, the results are given for two different circumburst environments.]]
-[[File:F2.jpg|thumb|400px|border|right|The average GRB orphan-afterglow detection rate in five years in the case of two different circumburst environments.]]
+[[File:F6.jpg|thumb|400px|border|right|Distribution of magnitudes, which are associated with detected afterglows (black), same magnitudes at the time of the first detection (grey) and magnitudes of afterglows detected by the second telescope (red) in the case of on-axis simulation. The results are given for a time of five years.]]
-[[File:F4.jpg|thumb|400px|border|right|Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change during the afterglow presence in the field of view (gray).]]
+In order to predict the number of optical afterglow detections with Gaia in five years of it's time of operation, a simulation was performed. The simulation took into account a scanning law of Gaia, it's field of view, etc. It consists of two parts: one for regular 'on-axis' afterglows and the other for orphan afterglows. In the former the observational data were used to constrain the parameters needed in the simulation (i.e. initial afterglow magnitude distribution, number of afterglows occuring in five years, etc.), while in the latter the parameters were obtained from theoretical predictions. Details on the simulation are given in [[#Simulation references|simulation references]].
-In order to predict the number of optical afterglow detections with Gaia in five years of it's time of operation, a simulation was performed. The simulation took into account a scanning law of Gaia, it's field of view, etc. It consists of two parts: one for regular 'on-axis' afterglows and the other for orphan afterglows. In the former the observational data were used to constrain the parameters needed in the simulation (i.e. initial afterglow magnitude distribution, number of afterglows occuring in five years, etc.), while in the latter the parameters were obtained from theoretical predictions. Details of on-axis and orphan afterglow simulation are given in [[#Simulation references|simulation references]].
+Number of detections in respect to limiting magnitude are shown on the the right in the top figure for the case of on-axis and orphan afterglows. The average GRB orphan-afterglow detection rate has been simulated for two different circumburst environments.
 Bottom, left figure shows initial magnitude distribution of detected on-axis afterglows (black), same distribution at the time of the first detection (gray) and the distribution of detections with the second telescope. Similar plot for orphan afterglows is given in [[#Simulation references|references]].
-Since GRB afterglows are initially rapidly fading and they will be observed for 4.4 seconds by each CCD camera, the change of magnitude in that time could in principle be observable. For all detected afterglows in our simulations, we therefore calculated the change of magnitude in 4.4 s, corresponding to observations by two successive CCDs, and also for observations lasting as long as a specific afterglow is in the telescope's field of view. The distribution of the change of magnitude for both cases is shown in the bottom figure on the right. Since the expected photometric error of Gaia at $M_{\rm lim} = 20$ mag will be 10 mmag at best (but probably bigger [http://www.rssd.esa.int/index.php?project=GAIA&page=index ESA]), the chances of observing the change in magnitudes will be small.
+Since GRB afterglows are initially rapidly fading and they will be observed for 4.4 seconds by each CCD camera, the change of magnitude in that time could in principle be observable. For all detected afterglows in our simulations, we therefore calculated the change of magnitude in 4.4 s, corresponding to observations by two successive CCDs, and also for observations lasting as long as a specific afterglow is in the telescope's field of view. The distribution of the change of magnitude for both cases is shown in the bottom figure on the right. Since the expected photometric error of Gaia at $M_{\rm lim} = 20$ mag will be 10 mmag at best (though it will be smaller for brighter sources [http://www.rssd.esa.int/index.php?project=GAIA&page=index ESA]), the chances of observing the change in magnitudes will be small.
-To summarize: the number of expected orphan afterglow detections with the Gaia satellite during it's five years of expected operation is of the order of 10. Adding the results of the on-axis afterglows simulation, the number of expected optical afterglow detections in five years is slightly increased. The problem of afterglow recognition and poor time sampling of the lightcurve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
+To summarize: the number of expected GRB optical afterglow detections with Gaia satellite during it's five years of expected operation is of the order of a few tens. Most of the expected detections are of the orphan afterglows, while the possibility of an on-axis afterglow detection is small (less than 10). The problem of afterglow recognition and poor time sampling of the lightcurve, in addition to the small number of expected detections, makes the study of GRB optical afterglows with Gaia difficult. On the other hand, since orphan afterglows have not been conclusively detected yet, a possible detection would provide valuable new data.
-[[File:F3.jpg|thumb|400px|border|center|Distribution of initial magnitudes, which are associated with detected afterglows (black), same magnitudes at the time of the first detection (gray) and magnitudes of afterglows detected also by the second telescope (red).]]
+[[File:F10.jpg|thumb|400px|border|center|Left: Distribution of the change in magnitude in 4.4 s (corresponding to an observation with 2 successive CCDs) (black) and the change of magnitude in the time in which an afterglow is in the entire field of view (red) for the on-axis case. Right: Distribution of the change in magnitude in the time in which an orphan afterglow is in the field of view. Black distribution corresponds to detection after the peak in a lightcurve while red distribution corresponds to detection before the peak.]]
 == Simulation references ==
-*J. Japelj, A. Gomboc, 2011, [http://www.fmf.uni-lj.si/~gomboc/report.pdf The estimation of detectability of on-axis GRB optical afterglows with Gaia]
+*J. Japelj, A. Gomboc, Gaia Alerts Workshop 2011, [http://www.ast.cam.ac.uk/~wyrzykow/GAIA/GSAW2011/Talks/gaia_alerts_japelj.pdf presentation] and [http://www.ast.cam.ac.uk/~wyrzykow/GAIA/GSAW2011/Movies/Japelj-GRBs.mov video recording] of the talk: The detectability of GRB optical counterparts with Gaia
-*J. Japelj, A. Gomboc, 2011, [http://www.fmf.uni-lj.si/~gomboc/reportOA.pdf The estimation of detectability of GRB optical orphan afterglows with Gaia]
+*J. Japelj, A. Gomboc, 2011, [http://arxiv.org/abs/1107.2858 arXiv:1107.2858]
 [[User:Jure.Japelj|Jure Japelj]] 18:09, 31 March 2011 (UTC)

@@ Line 42: / Line 42: @@
 *J. Japelj, A. Gomboc, 2011, [http://www.fmf.uni-lj.si/~gomboc/report.pdf The estimation of detectability of on-axis GRB optical afterglows with Gaia]
-*J. Japelj, A. Gomboc, 2011, The estimation of detectability of GRB optical orphan afterglows with Gaia
+*J. Japelj, A. Gomboc, 2011, [http://www.fmf.uni-lj.si/~gomboc/reportOA.pdf The estimation of detectability of GRB optical orphan afterglows with Gaia]
 [[User:Jure.Japelj|Jure Japelj]] 18:09, 31 March 2011 (UTC)

@@ Line 41: / Line 41: @@
 == Simulation references ==
-[http://www.fmf.uni-lj.si/~gomboc/report.pdf download]
+*J. Japelj, A. Gomboc, 2011, The estimation of detectability of on-axis GRB optical afterglows with Gaia [http://www.fmf.uni-lj.si/~gomboc/report.pdf download]
 *J. Japelj, A. Gomboc, 2011, The estimation of detectability of GRB optical orphan afterglows with Gaia

← Older revision		Revision as of 13:10, 5 April 2011
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	== Simulation references ==		== Simulation references ==
		+
		+	[http://www.fmf.uni-lj.si/~gomboc/report.pdf download]

	*J. Japelj, A. Gomboc, 2011, The estimation of detectability of on-axis GRB optical afterglows with Gaia		*J. Japelj, A. Gomboc, 2011, The estimation of detectability of on-axis GRB optical afterglows with Gaia