CALET と MAXI で観測されている突発天体 坂本 貴紀、川久保 雄太、 橋本 達也 (青学)、中平 聡志 (JAXA)、芹野 素子 (理研)

Contents CALET MAXI CALET-MAXI simultaneously observed GRBs Overview of CALET GRBs observed by CALET Gamma-ray Burst Monitor MAXI MAXI observation of GRBs MAXI Unidentified Short Soft Transient (MUSST) CALET-MAXI simultaneously observed GRBs GRB 160101A: Broad-band prompt emission observation GRB 160107A: Soft X-ray emission before the main episode FRB 131104: Re-visit Swift/BAT data (bonus) 11/30/16 High energy astro 2016@AGU

Overview of CALET: CALorimetric Electron Telescope 11/30/16 High energy astro 2016@AGU

CALET (CALorimetric Electron Telescope) Observatory of high energy electrons and gamma-rays Observation of high energy cosmic-rays All sky gamma-ray survey (> 10 GeV) High energy transients (GRBs, SGRs, …) CGBM/HXM CGBM/SGM CAL ASC MAXI Scientific instruments: CALorimeter (CAL) Electrons: 1 GeV – 20 TeV Gamma-rays: 10 GeV – 10 TeV (a few GeV – 10 TeV) Protons and Heavy ions: (~10 GeV – 1 PeV) CALET Gamma-ray Burst Monitor (CGBM) Hard X-ray Monitor (HXM): 7 keV – 1 MeV Soft Gamma-ray Monitor (SGM): 100 keV – 20 MeV CALET (port#9) ©JAXA 11/30/16 High energy astro 2016@AGU

CAL (CALorimeter) Gamma-ray performance CHD (Charge Detector): (Charge measurement: Z=1-40) IMC (Imaging Calorimeter): (Arrival direction and event ID) TASC (Total Absorption Calorimeter): (Energy measurement and event ID) 1 TeV electron shower (simulation) Gamma-ray performance CALET simulation (>10 GeV; 3 year) CAL Energy range (photon) 10 GeV-10 TeV Effective area 600 cm2 (@ 10 GeV) Angular resolution 2.5°@1 GeV 0.35°@10GeV FOV ~2 sr Crab Vela Galactic diffuse 11/30/16 High energy astro 2016@AGU

CALET Gamma-ray Burst Monitor (CGBM) Hard X-ray Monitor (HXM) Soft Gamma-ray Monitor (SGM) HXM SGM Detector (Crystal) LaBr3(Ce) BGO Number of detector 2 1 Diameter [mm] 61 102 Thickness [mm] 12.7 76 Energy range [keV] 7-1000 100-20000 Energy resolution@662 keV ~3% ~15% Field of view ~3 sr ~2p sr 100 HXM x 2 Effective area [cm2] 10 SGM 1 11/30/16 High energy astro 2016@AGU 10 100 1000 10000 Energy [keV]

CALET GRB Observation On-board CGBM trigger response: Stored the CGBM event data Lower the energy range of CAL to ~1 GeV Capture two optical images by ASC CAL CGBM ASC Energy range 1 GeV – 10 TeV (10 GeV – 10 TeV) HXM: 7 keV – 1 MeV SGM: 100 keV – 20 MeV 3000-8000 A Angular resolution 2.5o (@ 1 GeV) 0.35o (@ 10 GeV) - ~1” Field of view ~2 sr HXM: ~ 3 sr SGM: ~ 2p sr 18.4o x 13.4o Time resolution 62.5 ms GRB trigger: 62.5 ms (event data) Regular: 125 ms (8 ch), 4 s (512 ch) 0.5 s x 2 [8.6 mag (R)] 11/30/16 High energy astro 2016@AGU

CGBM Operation Status Scientific observation: October 6, 2015 Observation efficiency: ~60% (HV-on time) On-board trigger alert (GCN notice) (http://gcn.gsfc.nasa.gov/calet_triggers.html) Alert rate: 15 alerts/month Only send alert when we have a connection to ISS (~70% of time) Light curves are available at http://cgbm.calet.jp/cgbm_trigger/flight/ 11/30/16 High energy astro 2016@AGU

GRBs Observed by CGBM 11/30/16 High energy astro 2016@AGU

CGBM GRB light curve gallery GRB151006A GRB151015A GRB151107B GRB151210B GRB151212B HXM1 50-250 keV HXM1 50-2500 keV HXM2 50-2500 keV SGM 40-1000 keV HXM2 50-250 keV HXM2 50-2500 keV SGM 40-230 keV SGM 40-230 keV SGM 40-1000 keV GRB151225A GRB151227B GRB151231A GRB160101A SGM 40-1000 keV HXM1 7-100 keV HXM1 50-150 keV HXM1 7-100 keV SGM 40-1000 keV SGM 40-1000 keV SGM 40-230 keV GRB160106A GRB160107A GRB160118A GRB160223B HXM1 7-100 keV HXM1 7-100 keV HXM1 7-100 keV SGM 40-1000 keV HXM2 7-100 keV HXM2 7-100 keV HXM2 7-100 keV SGM 7-100 keV SGM 40-1000 keV SGM 40-1000 keV 11/30/16 High energy astro 2016@AGU

CGBM GRB Statistics 49 GRBs (including 4 possible GRBs) GRB rate: ~48 GRBs/yr 40 long GRBs (82%), 9 short GRBs (18%) Simultaneous GRB detection by: Fermi-GBM: 76% (31 GRBs) Swift-BAT: 30% (12 GRBs; including GRBs with outside the field of view of BAT) Konus-Wind: 49% (20 GRBs) MAXI-GSC: 10% (4 GRBs) 3 known-z GRBs (160509A: z=1.17, 160623A: z=0.367, 160625B: z=1.406) (Fermi-GBM: 82% long GRBs, 18% short GRBs (Paciesas et al. 2012) 11/30/16 High energy astro 2016@AGU

T90 Duration Distribution 6 CGBM 40-1000 keV 4 2 100 BATSE 25-350 keV 50 Number of GRBs Fermi-GBM 50-300 keV 200 100 Swift-BAT 15-350 keV 100 50 0.001 0.01 0.1 1 10 100 1000 T90 [s] 11/30/16 High energy astro 2016@AGU

T90 Duration Distribution 6 CGBM 40-1000 keV 4 2 100 BATSE 25-350 keV 50 Number of GRBs Fermi-GBM 50-300 keV 200 100 Swift-BAT 15-350 keV 100 50 0.001 0.01 0.1 1 10 100 1000 T90 [s] Both short and long GRBs are detected (similar fraction to Fermi-GBM). 11/30/16 High energy astro 2016@AGU

T90 Duration Distribution 6 CGBM 40-1000 keV 4 2 100 BATSE 25-350 keV 50 Number of GRBs Fermi-GBM 50-300 keV 200 100 Swift-BAT 15-350 keV 100 50 0.001 0.01 0.1 1 10 100 1000 T90 [s] Both short and long GRBs are detected (similar fraction to Fermi-GBM). 11/30/16 High energy astro 2016@AGU

T90 Duration Distribution Comparison of the effective area T90 duration has a strong instrumental effect. GRB 151006A SGM High (40-1000 keV) SGM Low (0.6-30 MeV) Fermi-GBM NaI (7-2000 keV) Rate [c/s] Fermi-GBM BGO (0.1 – 50 MeV) (Meegan et al.) Swift-BAT (15-150 keV) Time since the trigger [s] 11/30/16 High energy astro 2016@AGU

T90 Duration Distribution 6 CGBM 40-1000 keV 4 2 100 BATSE 25-350 keV 50 Number of GRBs Fermi-GBM 50-300 keV 200 100 Swift-BAT 15-350 keV 100 50 0.001 0.01 0.1 1 10 100 1000 T90 [s] Both short and long GRBs are detected (similar fraction to Fermi-GBM) The shorter T90 for long GRBs (tip of the iceberg effect?) 11/30/16 High energy astro 2016@AGU

Energy fluence vs. T90 duration CGBM triggered Fermi-GBM GRBs Fermi-GBM GRBs 5 Crab (= 1.9 x 10-7 erg/cm2/s) 1 Crab (= 3.8 x 10-8 erg/cm2/s) Energy fluence (10-1000 keV) [erg cm-2] 6 x 10-7 erg/cm2 T90 duration [sec] 11/30/16 High energy astro 2016@AGU

64 ms peak photon flux [ph cm-2 sec-1] Peak flux vs. T90 duration CGBM triggered Fermi-GBM GRBs Fermi-GBM GRBs 64 ms peak photon flux [ph cm-2 sec-1] (10-1000 keV) 10 ph/cm2/s (~16 Crab) 3 ph/cm2/s (~5 Crab) T90 duration [sec] 11/30/16 High energy astro 2016@AGU

Other Transient Events Short bursts from SGR 1935+2154 Solar flares SGM 40-100 keV HXM 7-10 keV 2016/6/20 15:16:34.8 HXM 10-25 keV 2016/6/23 21:20:46.3 Rate [c/s] Rate [c/s] HXM 25-50 keV 2016/6/24 10:22:09.3 HXM 50-100 keV Time since the trigger [sec] Time since 7/18/2016 8:12:07 [sec] 11/30/16 High energy astro 2016@AGU

CAL Gamma-ray Performance Gamma-ray signal search for GW 151226 by CAL (Andriani et al. 2016) CAL effective area in this analysis Gamma-ray event selection 600 Good shower characteristics No Hits in CHD and at the top IMC Layer >1 GeV 0 < q < 5o 17.5o < q < 22.5o 27.5o < q < 32.5o 500 Simulation 400 Effective area [cm2] 300 CHD 200 IMC 100 CAL all sky map TASC 0.1 1 10 100 Energy [GeV] CAL all sky map 2015/10/13 – 2016/05/31 Fermi-LAT (on-axis) Preliminary > 1 GeV Geminga Galactic Latitude Crab (Note: non-uniform exposure) 11/30/16 High energy astro 2016@AGU Galactic Longitude

Summary: CALET CALET started its scientific observation since October 2015. CGBM detected 49 GRBs as of today (detection rate of 48 GRBs/yr). 82% long GRBs and 18% short GRBs (similar to Fermi-GBM). CGBM fluence GRB sensitivity is ~6 x 10-7 erg/cm2 (10-1000 keV). CGBM peak flux GRB sensitivity is ~3 ph/cm2/s1 (10-1000 keV) for long GRBs and ~10 ph/cm2/s1 (10-1000 keV) for short GRBs. CGBM spectral calibration and CAL gamma-ray analysis for GRBs are on-going. 11/30/16 High energy astro 2016@AGU

MAXI Observations of GRBs 11/30/16 High energy astro 2016@AGU

Highlight of MAXI Transients (Negoro et al. 2016) Atel & GCN reported numbers BHC: 6 (new), 6 (known) NS LMXB: 4 (new), 13 (known) Pulsar: 1 (new), 18 (known) SFXT: 0 (new), 2 (known) WD: 1 (new), 0 (known) Stars: 21 AGN: 6 GRB: 63 11/30/16 High energy astro 2016@AGU

MAXI/GSC Performance Performance Energy range: 2-30 keV FOV: 3 deg x 160 deg (horizontal and zenith directions) Typical transit time: 40-100 s Maximum effective area: 20 cm2 Position accuracy: 0.2-0.5o (radius) + 0.1o (sys) (1.5 - 2o) x (0.2-0.5o) (box) + 0.1o (sys) Same FOV point source: Operation GSC operates between latitude ± 40 deg (avoid a risk of discharge to carbon wires) Operation efficiency: 80% 40% 11/30/16 High energy astro 2016@AGU

GRB Prompt Emission Spectrum GRB 050525A Epeak E-0.5 (E-2.5) E (E-1) nFn Band function (Band et al. 1993) Energy [keV] 11/30/16 High energy astro 2016@AGU

X-Ray Flashes (XRFs) (Ginga and BeppoSAX era) Ginga (Strohmayer et al. 1998) WFC / BATSE (Kippen et al. 2002) 10 100 1000 Ep (keV) Peak Flux P1024 (ph cm-2 s-1) (22 GRBs) Number of Events 1 2 3 4 log Ep [keV] XRFs: “Gamma-ray” bursts which emits most of the emission in X-rays 11/30/16 High energy astro 2016@AGU

HETE XRFs HETE-2 Epeak Distribution (Sakamoto et al. ) 2- 5 keV XRF 020903 HETE-2 Epeak Distribution (Sakamoto et al. ) 5- 10 keV 10 39 Samples BATSE GRBs 8 30 keV 10- 25 keV 6 Count rate [c/s] Number of Events 4 6- 40 keV 2 6- 80 keV 0 0.5 1 1.5 2 2.5 3 Log (Epeak) [keV] 30- 400 keV Broad Epeak distribution, extension to the low energy range 11/30/16 High energy astro 2016@AGU Time [s]

MAXI GRB Catalog 35 GRBs 15 GRBs (~40%) (4 known-z GRBs) (Serino et al. 2014) From August 15, 2009 to middle of 2013: 35 GRBs 15 GRBs (~40%) (4 known-z GRBs) Simultaneously observed by other GRB instruments (Fermi-GBM/LAT, Konus-Wind, Swift/BAT, INTEGRAL) (Excluding unID transients in galactic latitude ±10 deg.) 25 GRBs (~60%): MAXI only detection MAXI/GSC GRB rate: ~ 10 GRBs/yr Typical delay time in sending MAXI GSC location to the community (e.g., GCN) 2 hours - a few days 11/30/16 High energy astro 2016@AGU

GRB Light curve and Spectrum http://maxi.riken.jp/grbs GRB 091120 (1s bin) GRB 090831 (MAXI/GSC+Fermi/GBM) Fermi/GBM MAXI/GSC GRB 100823 (MAXI/GSC+Swift/BAT) MAXI/GSC Swift/BAT 11/30/16 High energy astro 2016@AGU

MAXI XRF 100315A No obvious emission above 10 keV Hardness ratio (8-20 keV) / (2-8 keV) = 0.25 ± 0.13 4-10 keV (Epeak < 5 keV) 10-20 keV No obvious emission above 10 keV 11/30/16 High energy astro 2016@AGU

Hardness Ratio vs. Flux MAXI GRBs are weak and soft. 8-20 keV 2-8 keV 11/30/16 High energy astro 2016@AGU

log N-log F of MAXI GRBs All GRBs MAXI+others MAXI only Similar results in HETE-2 GRB sample (Sakamoto 2004) 11/30/16 The distance of XRFs can be closer to the Euclidean space. High energy astro 2016@AGU

log N – log P of HETE XRFs 20 (Sakamoto Ph.D. thesis) 10 XRF GRB (Ep > 50 keV) 5 N (>P) P -3/2 2 1 1 10 100 P 2 - 30 keV (ph cm-2 s-1) 11/30/16 The distance of XRFs are close to the Euclidean space. High energy astro 2016@AGU

log N-log F of MAXI GRBs All GRBs MAXI+others MAXI only F-3/2 Similar results in HETE-2 GRB sample (Sakamoto 2004) 11/30/16 The distance of XRFs can be closer to the Euclidean space. High energy astro 2016@AGU

MAXI Unidentified Short Soft Transient (MUSST) 11/30/16 High energy astro 2016@AGU

What is MUSST? Unidentified X-ray source > 0.1 Crab in flux at detection, but only detected in a single GSC scan Only detected by MAXI (no detection by other satellite) No X-ray counterpart found by Swift/XRT follow-up observations 11/30/16 High energy astro 2016@AGU

MUSST List Name (RA, Dec) T0 (MAXI) MAXI T0 2-20 keV Flux Swift ToO Time Swift/XRT 3 s UL 0.3-10 keV Flux 1 MAXI J1501-026 (225.368, -2.603) 2015-08-26 15:40:57 1.3 x 10-8 T0+1.7 hour 1.9 x 10-12 (2.3 x 10-12) 2 GRB 150428C (60.247, 67.818) 2015-04-28 08:24:15 4.9 x 10-9 T0+4.5 hour 1.1 x 10-12 (1.6 x 10-12) 3 MAXI J1540-158 (235.099, -15.809) 2015-03-11 16:18:16 3.1 x 10-9 T0+2.0 day 9.3 x 10-13 (1.1 x 10-12) 4 GRB 140814A (182.515, 49.348) 2014-08-14 07:12:31 7.1 x 10-9 T0+6.3 hour 4.4 x 10-13 (4.7 x 10-13) 5 MAXI J0545+043 (86.44, 4.32) 2014-04-12 00:25:54 6.2 x 10-9 T0+1.1 day 2.2 x 10-12 (3.3 x 10-12) 6 GRB 130407A (248.10, 10.51) 2013-04-07 23:37:01 5.2 x 10-9 T0+15.6 hour 3.8 x 10-13 (4.4 x 10-13) 7 MAXI J1631-639 (247.83, -63.95) 2011-04-29 16:12:38 3.7 x 10-9 4.6 x 10-13 (6.1 x 10-13) Flux in the unit of erg/cm2/s. Swift/XRT upper limit is in the observed flux and the flux in the parenthesis is unabsorbed flux. 11/30/16 High energy astro 2016@AGU

MUSST GSC Localization and Swift/XRT Tiling Observation MAXI J1501-026 GRB 150428C MAXI J1540-158 XRT field of view 33’ MAXI error region GRB 140814A MAXI J0545+043 GRB 130407A MAXI J1631-639 11/30/16 High energy astro 2016@AGU

X-ray Upper Limit by Swift/XRT Follow-up Observations 1 2 3 4 5 6 7 11/30/16 High energy astro 2016@AGU

Flux vs. Hardness of MUSST HETE GRB HETE XRF MAXI + Others MAXI only MUSST 11/30/16 High energy astro 2016@AGU

MUSST is similar to XRFs (Sakamoto et al. 2008) - XRFs have a lower X-ray afterglow flux/luminosity comparing to C-GRBs. Similar trend to what XRT upper limits are suggesting for MUSST. 11/30/16 High energy astro 2016@AGU

Summary: MAXI MAXI GRBs MUSST MAXI/GSC GRB rate: ~10 GRBs/yr 2/3 of MAXI GRBs (MAXI only detection) have a soft spectrum (no emission above 10 keV) MAXI only soft GRBs shows a similar log N- log F distribution to that of HETE-2 XRFs (closer to -2/3 slope) MUSST 7 MUSST (2011-2015) Swift/XRT X-ray UL suggests MUSST is populated at a low X-ray afterglow flux region (if MUSST is associated to GRBs) MUSST ~ XRFs? 11/30/16 High energy astro 2016@AGU

CALET-MAXI simultaneously observed GRBs 11/30/16 High energy astro 2016@AGU

Field of view of MAXI and CGBM MAXI GSC MAXI SSC Paddle SGM: 2 pi str: 20626 deg^2 MAXI/GSC: 3 deg x 160 deg = 480 deg^2  FOV fraction (SGM/GSC) = 43: バッチリ FOV が合うのは年間 1個 FOV of HXM FOV of SGM 11/30/16 High energy astro 2016@AGU

Four MAXI-GSC and CGBM Simultaneously Detected GRBs GRB 160101A GRB 160107A MAXI/GSC 2-4 keV MAXI/GSC 2-4 keV Rate [c/s] Rate [c/s] CGBM 60-100 keV (HXM) CGBM 7-10 keV (HXM) Time since trigger [s] Time since trigger [s] GRB 160509A GRB 160814A MAXI/GSC 2-4 keV MAXI/GSC 2-4 keV Rate [c/s] Rate [c/s] CGBM 100-450 keV (SGM) CGBM 7-10 keV (HXM) 11/30/16 High energy astro 2016@AGU Time since trigger [s] Time since trigger [s]

GRB 160101A Trigger time: CGBM: 2016-01-01 00:43:54 (UT) MAXI: 2016-01-01 00:43:52 (UT) Also triggered Fermi-GBM/Konus-Wind S (20 keV – 10 MeV): 1.5 x 10-5 [erg/cm2] Epeak ~ 140 keV Swift ToO observation (T0+13.2 – T0+19.6 ks) One X-ray AG candidate MAXI/GSC 2-4 keV MAXI/GSC 4-10 keV MAXI/GSC 10-20 keV CGBM/HXM 60-100 keV Rate [c/s] MAXI-GSC spectrum (1 scan; time-averaged) CGBM/HXM 100-170 keV Single power-law CGBM/HXM 170-300 keV alpha = -0.9 ± 0.1 CGBM/HXM 300-3000 keV Time since trigger [s] 11/30/16 High energy astro 2016@AGU

GRB 160101A: Energy-resolved T90 duration GRB 021211 (Crew et al. 2003) T90 ~ E-0.40 T90 ~ E-0.44 MAXI-GSC T90 [s] CGBM Fenimore relation: Pulse-width ~ E-0.40 (Fenimore et al. 1995) Energy [keV] 11/30/16 High energy astro 2016@AGU

GRB 160107A: Pre-burst emission MAXI detection: T0 (CGBM) - 45 s MAXI/GSC spectrum: Highly absorbed power-law NH = (6 ± 3) x 1022 cm-2 alpha = -3.0 ± 0.7 Blackbody kT = 1.3 ± 0.2 keV MAXI-GSC 2-4 keV MAXI-GSC 4-10 keV MAXI-GSC 10-20 keV HXM 7-10 keV HXM 10-25 keV Rate [c/s] HXM 25-50 keV HXM 10-25 keV HXM 50-100 keV SGM 100-230 keV SGM 230-450 keV Rate [c/s] SGM 450-1000 keV Time since trigger [s] 11/30/16 High energy astro 2016@AGU Time since trigger [s]

Pre-burst Emission & Quiescent Period Yamazaki 2009 BAT survey data search (Lien et al. 2016) 1 possible detection (4.7 s) / 794 GRBs No bright pre-burst emission found in the BAT data. X-ray emission at the quiescent period GRB 050820A BAT 15-350 keV Rate [c/s/det] XRT 0.3-10 keV Alpha = -2.01 ± 0.15 Flux [erg/cm2/s] If a true burst T0 is few hours before the instrument oriented T0, the shallow decay seen in XRT is no longer shallow (close to normal decay). Time since BAT trigger [s] High sensitive wide-field soft X-ray survey!! 11/30/16 High energy astro 2016@AGU

Summary: CALET-MAXI GRBs Four GRBs (GRB 160101A, GRB 160107A, GRB 160509A and GRB 160814A) are simultaneously detected by CGBM and MAXI/GSC. GRB 160101A: 2-3000 keV broad-band GRB prompt light curve is available. GRB 160107A: MAXI/GSC detected the emission 45 s prior to the main GRB episode. 11/30/16 High energy astro 2016@AGU

GRB conference 2018? in Japan At Huntsville GRB conference, Valerie Connaughton (LOC, SOC) asked me for a possibility of organizing GRB conference (two years from now) in Japan. Yokohama Multi-messenger GRB 2018? 11/30/16 High energy astro 2016@AGU

FRB 131104: Re-visit Swift/BAT data 11/30/16 High energy astro 2016@AGU

12th Anniversary of Swift!! Launch: November 20, 2004 (12th year on-orbit!) 2016 NASA senior review: Swift ranked No. 1!! >1000 GRBs detected (~90 GRBs/yr) (Lien et al. 2016) No hardware issue “Many more years of discovery with Swift!!” (Neil Gehrels) 11/30/16 High energy astro 2016@AGU

Hard X-ray Counterpart of FRB 131104? 11/30/16 High energy astro 2016@AGU

BAT Image Analysis Flux mask (default) Detection mask Sky image using the flux mask Sky image using the detection mask FRB 131104 position FRB 131104 position 11/30/16 High energy astro 2016@AGU

BAT 64 ms Raw Light Curve BAT 14-24 keV BAT 24-50 keV BAT 50-100 keV No excess signal in the BAT raw 64 ms light curve BAT 100-195 keV 11/30/16 High energy astro 2016@AGU

BAT 1.6 s Light Curve (quad-rate) BAT mask shadow of FRB 131104 direction Quad0 Quad1 Quad1 Quad2 Quad3 Quad2 Partial coding fraction: 6% coding Quad3 11/30/16 High energy astro 2016@AGU

BAT Survey Data Analysis 14-24 keV 24-50 keV No significant detection around T0 in the BAT survey data. 50-100 keV 100-195 keV 11/30/16 High energy astro 2016@AGU

BAT Scaled Map Analysis 15-50 keV Rate [c/s/det] Time since 18:03:59.000 UTC [s] 11/30/16 High energy astro 2016@AGU

Summary: BAT FRB 131104 The BAT detection claim of the hard X-ray counterpart of FRB 131104 is not convincing. The position was extremely partial coded FOV which requires a full coded mask to generate the image (not recommended in a standard analysis). Doesn’t show any excess in the raw light curve. Furthermore, no excess in the light curve of quadrant#3 (inconsistent with the mask image). The light curves generated by the image analysis (survey data and scaled map data) are both consistent with zero flux around the FRB trigger time. 11/30/16 High energy astro 2016@AGU