Detection capability of UltraLong Gamma-Ray Bursts with the ECLAIRs telescope aboard the SVOM mission N I C O L A S D A G O N E A U ( C E A S A C L AY ) – N I C O L A S . D A G O N E A U @ C E A . F R 1 ST Y E A R P H D S T U D E N T - S U P E R V I S E D BY S T É P H A N E S C H A N N E PNHE WORKSHOP – JOURNÉES SF2A 2018
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The SVOM Mission Space-based multiband astronomical Variable Objects Monitor SVOM: build a homogeneous sample of GRBs with a good timing and spectral coverage and redshift measurement, including X-ray rich, high-redshift, off-axis jet GRBs. White paper: Wei,Cordier+2016 arXiv:1610:06892
Multi wavelength follow-up from space and ground Phase C mission, to be launched by end of 2021 in Xichang (China).
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor
From space From ground
FSC
CSC
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Inside SVOM Outside SVOM
VHF
SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
From space From ground
FSC
CSC
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Inside SVOM Outside SVOM
VHF
SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
From space From ground
VHF
FSC
CSC
05/07/2018
Inside SVOM Outside SVOM
T0+30s
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
From space From ground
VHF
FSC
CSC
Inside SVOM Outside SVOM
T0+30s
Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
From space From ground
VHF
FSC
CSC
Inside SVOM Outside SVOM
T0+30s
Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
From space From ground
VHF
Inside SVOM Outside SVOM
T0+30s
FSC
CSC T0+5min
Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
Auto slew
From space From ground
VHF
Inside SVOM Outside SVOM
T0+30s
FSC
CSC T0+5min
Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
Auto slew
From space From ground
VHF
Inside SVOM Outside SVOM
T0+30s
FSC
CSC T0+5min
Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
Auto slew
From space From ground
VHF
Inside SVOM Outside SVOM
T0+30s
FSC
CSC
Other space missions
T0+hours/days
T0+5min Alert Broadcast
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SF2A 2018
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The SVOM Mission scenario Space-based multiband astronomical Variable Objects Monitor T0=trigger GRB
Auto slew
From space From ground
VHF
Inside SVOM Outside SVOM
T0+30s
FSC
CSC
Other space missions
T0+hours/days
T0+5min Alert Broadcast
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SF2A 2018
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Onboard GRB detection with ECLAIRs Detection using two different trigger algorithms (adapted to GRBs diversity): Count rate trigger (10ms – 20s): monitor count-rate on detector and process sky image for best significant excess. Image trigger (20s – 20min): process sky images every 20s and search for excess.
UGTS Application Layer architecture (S. Schanne) 05/07/2018
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Onboard GRB detection with ECLAIRs Image processing (for image trigger): background (CXB and known sources) modelization and subtraction in detector image before deconvolution.
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Onboard GRB detection with ECLAIRs Image processing (for image trigger): background (CXB and known sources) modelization and subtraction in detector image before deconvolution. Raw shadowgram (counts in 20s): • Earth modulated CXB • GRB contribution ? • Known sources, depending on pointing (yes in this case) source-illumination models are known
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Onboard GRB detection with ECLAIRs Image processing (for image trigger): background (CXB and known sources) modelization and subtraction in detector image before deconvolution. Raw shadowgram (counts in 20s): • Earth modulated CXB • GRB contribution ? • Known sources, depending on pointing (yes in this case) source-illumination models are known Model shadowgram (counts in 20s): • Quadratic CXB (6 parameters): • m = 𝑎𝑥 2 + 𝑏𝑦 2 + 𝑐𝑥 + 𝑑𝑦 + 𝑒𝑥𝑦 + 𝑓 • Known sources models (1 param. per source), 5 sources max TBC • Fitting to raw shadowgram
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Onboard GRB detection with ECLAIRs Model subtracted shadowgram (counts in 20s): • Reduced non uniformity due to Earth modulated CXB • Reduced sources contribution (non subtracted ones remain but are fainter)
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Onboard GRB detection with ECLAIRs Model subtracted shadowgram (counts in 20s): • Reduced non uniformity due to Earth modulated CXB • Reduced sources contribution (non subtracted ones remain but are fainter)
y (sky pixel)
Deconvolution of cleaned shadowgram sky (SNR in 20s): • Part is occulted by Earth
y (sky pixel)
• Part is too close to known sources
x (sky pixel) 05/07/2018
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Onboard GRB detection with ECLAIRs Histogram of pixel values in SNR sky image (without excluded zones) in a “well
cleaned” sky: standard deviation of pixels distribution ≈ 𝟏 sigma (in 20s)
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Onboard GRB detection with ECLAIRs Histogram of pixel values in SNR sky image (without excluded zones) in a “well
cleaned” sky: standard deviation of pixels distribution ≈ 𝟏 sigma (in 20s)
In case of a GRB (here GRB 000126)
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Towards ultra-long GRBs detection Ongoing work SVOM pointing strategy allows same pointing up to 1 day. Can it help to detect something new/different? For long GRB, no need to use long duration time slices For ultra-long GRB, simulation to come…
Ultra long GRB could be events at higher redshift: can ECLAIRs increase the size of the “observable GRB Universe” ? SVOM may detect ultra-long events: ulGRB, TDE, SN shock breakout
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Towards ultra-long GRBs detection Ongoing work Image trigger simulation for Heussaf GRB
GRB in center of field of view, no Earth Background: CXB and internal
SNR threshold = 6.5 sigma
Most of triggers in 20.48s images Same to be done with other GRB (Sakamoto, ulGRB) Simulation of GRB at higher redshift (with IAP simulator: F. Daigne, S. Antier, M. Bocquier) and study detection with trigger algorithms (S. Schanne)
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Towards ultra-long GRBs detection Ongoing work Some GRBs have longer duration (> 1000s) than classical long GRBs No clear definition of duration (𝑇90 , 𝑇𝑋 , 𝑇𝑏𝑢𝑟𝑠𝑡 ) New class (yes for Levan+13 and Boër+15, no for Virgili+13)
Levan+13
Origins: require a central engine powered during an ultra-long time (core collapse of a blue supergiant, magnetar birth, white dwarf TDE). (Gendre+13, Greiner+14, Ioka+16), BH of mass 109 𝑀𝑠𝑢𝑛 at 𝑧 ≥ 6 (Matsumoto+15) Characteristics: long emission after the burst, fast variations in X-ray plateau (flares or dips). In any cases: what could bring ECLAIRs ? 05/07/2018
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Towards ultra-long GRB detection Ongoing work Ultra-long GRB sample built from Swift/BAT GRB catalog summary tables : Few events
Lightcurve doesn’t look like very long (event if reported as ulGRB) or doesn’t show bright peak(s) No precise spectrum analysis (only Swift/BAT GCN one in 15-150keV) Some have unknown redshift
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Towards ultra-long GRB detection Ongoing work Imaging simulation from 10ms to 6400s GRB in center of field of view, no Earth
Spectrum: Band (𝐸𝑝𝑒𝑎𝑘 = 20keV, 𝛼 = −1, 𝛽 = −2 ) in 4-120keV Background: CXB and internal
SNR threshold = 6.5 sigma
Fluence threshold: 𝟏. 𝟑𝟏 𝒕 ph/cm2
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Towards ultra-long GRB detection Ongoing work Can ECLAIRs populate this region ?
Gendre+13
Virgili+13
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Towards ultra-long GRB detection Ongoing work Simulation of trigger with GRB in center of field of view, no additional sources Heussaf
Heussaf, 2015 : 84 GRB (spectrum from WK+Fermi) 84 trigged at catalog redshift 74 trigged at z = 5
ulGRB : 14 GRB 12 trigged at catalog redshift 6 trigged at z = 5
Same to be done with full Swift sample (known redshift) …
Simulation of GRB at higher redshift (with IAP simulator: F. Daigne, S. Antier, M. Bocquier) and study detection with trigger algorithms (S. Schanne) 05/07/2018
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Towards ultra-long GRB detection Ongoing work Simulation of trigger with GRB in center of field of view, no additional sources Heussaf Heussaf + ulGRB
Heussaf, 2015 : 84 GRB (spectrum from WK+Fermi) 84 trigged at catalog redshift 74 trigged at z = 5
ulGRB : 14 GRB 12 trigged at catalog redshift 6 trigged at z = 5
Same to be done with full Swift sample (known redshift) …
Need to be corrected: ulGRB fluences in [4-150keV], Heussaf fluences in [4-250keV] ECLAIRs threshold in [4-120keV]
Simulation of GRB at higher redshift (with IAP simulator: F. Daigne, S. Antier, M. Bocquier) and study detection with trigger algorithms (S. Schanne) 05/07/2018
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Towards ultra-long GRB detection Ongoing work Simulation of trigger with GRB in center of field of view, no additional sources ulGRB Heussaf Heussaf + ulGRB
Heussaf, 2015 : 84 GRB (spectrum from WK+Fermi) 84 trigged at catalog redshift 74 trigged at z = 5
ulGRB : 14 GRB 12 trigged at catalog redshift 6 trigged at z = 5
Same to be done with full Swift sample (known redshift) …
Need to be corrected: ulGRB fluences in [4-150keV], Heussaf fluences in [4-250keV] ECLAIRs threshold in [4-120keV]
Simulation of GRB at higher redshift (with IAP simulator: F. Daigne, S. Antier, M. Bocquier) and study detection with trigger algorithms (S. Schanne) 05/07/2018
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Conclusion ECLAIRs can perform long time imaging require background (CXB and sources) subtraction ECLAIRs may increase rate of detected (ultra-long and distant) GRB
Work to come: Study ECLAIRs fluence-Duration limit of trigger
Which time slices are needed for ulGRB detection. Check if ECLAIRs can detect TDE or SN shock breakout.
Questions addressed to the community: Can we use BATSE mean and variance redshift to attribute redshift to GRB?
Swift GRB 1/3 with redshift: is there a database newer than one of Heussaf? Swift GRB 1/3 with redshift: does it preserve the Swift population? 05/07/2018
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Thank you !
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ECLAIRs coded mask telescope • Coded mask: Ti-Ta-Ti • Field of view: 2sr (90x90 deg²) • Energy band : 4-120 keV • On axis sensitivity in 1s: 780 mCrab • Localization error: < 12 arcmin • Detection: ~ 60 GRB/year
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ECLAIRs coded mask telescope • Coded mask: Ti-Ta-Ti • Field of view: 2sr (90x90 deg²) • Energy band : 4-120 keV • On axis sensitivity in 1s: 780 mCrab • Localization error: < 12 arcmin • Detection: ~ 60 GRB/year
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ECLAIRs coded mask telescope • Coded mask: Ti-Ta-Ti • Field of view: 2sr (90x90 deg²) • Energy band : 4-120 keV • On axis sensitivity in 1s: 780 mCrab • Localization error: < 12 arcmin • Detection: ~ 60 GRB/year
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Known sources catalog
Sensitivity in 4-120 keV : 𝟕𝟖𝟎/ 𝒕 mCrab
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