Transients and Robotic Triggering at 15 GHz with AMI Gamma-ray Bursts (GRBs) ESO Gemma Anderson ICRAR-Curtin University 7 July 2016 gemma.anderson@curtin.edu.au Focus on triggering of high energy events – particularly GRBs

ICRAR-Curtin – science & engineering ‘I’m from ICRAR-Curtin, we are currently a group of  60 astronomers and engineers; our focus is R&D towards SKA including working with its precursor telescopes and data’. Accretion physics group Gemma Anderson, Transient triggering with AMI (ASA 2016)

Radio Transients All require robotic triggering! X-ray Binaries Gamma-ray Bursts Supernovae Tidal disruption Events Flare Stars Radio sky is extremely dynamic place – transients Study shocks and particle acceleration, probe magnetic fields and ISM from radio follow-up Difficult to get prompt response – when most interesting and dynamic physics occurring Require robotic triggering Each of these transients could have their own talk so today: Focus on GRBs All require robotic triggering! Gemma Anderson, Transient triggering with AMI (ASA 2016)

Robotic Transient Triggering Test bed for SKA Prompt GRB follow-up Test Fireball model - REVERSE shock Unbiased population Scientific payoff of interrupting observing programs for transients Benefits of simultaneous multi-wavelength observation Fireball model describes the production of the GRB afterglow as the shock propogates into the ISM Predicts a reveres shock that progates back into post-shock eject, creates more prompt emission like optical flashes and radio flares Gemma Anderson, Transient triggering with AMI (ASA 2016)

GRB radio robotic triggering Cambridge: 1990’s 151 MHz, BATSE GRBs Mt Pleasant 2.3 GHz, 5 Swift GRBs Parkes 12m dish 1.4 GHz 9 Swift GRBs Lots of robotic optical and X-ray follow-up Radio is rare Cambridge Low Frequency Synthesis Telescope Clearly there is a need to further explore this parameter space – particularly at higher frequencies MWA 80-133 MHz Swift & Fermi GRBs Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI Transient Program Arcminute Microkelvin Imager (AMI) – Large Array 15.7 GHz, 5’ primary beam, ~30’’ resolution Rapid Response Mode Swift trigger On target <5 mins Follow-up 24hrs, 3, 7, 10 days RMS 30-40 μJy >150 GRBs Flare stars, XRBs, magnetars http://www.mrao.cam.ac.uk/outreach/radio-telescopes/ami/ Gemma Anderson, Transient triggering with AMI (ASA 2016)

Radio Emission from GRBs First 15 years: Chandra & Frail (2012) 2995 flux densities and limits, 0.026-1339 days post-burst 30% radio GRBs Sensitivity, not intrinsic Radio follow-up of GRBs is biased! 3σ upper limits Put AMI in context Put AMI program into context Does NOT include robotic triggers mentioned before Put AMI radio observations in context 19 years of GRB radio detections Summary first 15 years Rarity radio telescopes Prior knowledge Detections Chandra & Frail (2012) Gemma Anderson, Transient triggering with AMI (ASA 2016)

Earliest Radio Observations of GRBs C&F: 304 GRBs AMI: 139 GRBs C&F: 304 GRBs AMI: 139 GRBs MWA: 16 GRBs Other: 17 GRBs 42 observed within first our post-burst Zoom in further its 40 GRBs within the first 36 mins post-burst => in first 14 years only ONE obs within 37 mins, in 3 years we have observed 40!!! First time true constraining the early time radio properties of GRBs with a significant number of events Project allow us to constrain radio properties of GRBs at extremely early times Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI Observations GRB 130427A One of earliest radio detection of LGRB AMI detection of the radio REVERSE SHOCK (rare!) Reverse Compared Perley et al. (2013) model Say all the stuff about how fast we were on target and the VLA observations! First detection of radio peak in GRB reverse shock! Forward Anderson et al. (2014), MNRAS, 440, 2059 Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI GRB Catalogue < 1hr to ~90 days post-burst 90.2 days AMI observing time 13 (12 Swift) radio GRBs 5 AMI discovered GRBs! AMI detection: 15% UNBIASED: ~0.1-0.2 mJy Increased known radio GRBs by 50% within 1.5 yrs This program allowed us to probe a unique parameter space and explore strategies for the SKA This experiment was uniquely possible with AMI and could not have been conducted on any other facility that are highly oversubscribed Anderson et al. in prep Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI GRB Catalogue Anderson et al. in prep 7 known 5 unknown 3 candidates 4 steady sources Anderson et al. in prep Gemma Anderson, Transient triggering with AMI (ASA 2016)

Conclusions AMI: longest running GRB robotic radio follow-up >150 GRBs Early radio detection First detection reverse shock peak 5 new radio GRBs (increase 50% over 1.5 years) 15% detection (0.1-0.2 mJy) Importance robotic triggering Explore SKA strategies This program allowed us to probe a unique parameter space and explore strategies for the SKA This experiment was uniquely possible with AMI and could not have been conducted on any other facility that are highly oversubscribed Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI Detection of DG CVn – flaring from a rapidly rotating M dwarf (24/04/2014) AMI observing <6 mins Quiescence in 4 days (2-3mJy) First radio flare associated γ-ray flare star Magnetic reconnection induces radio flaring: GYROSYNCHRTRON Reached 100mJy before dropping to quiescent level 2-3 mJy Particles accelerated during flaring process flare event encompasses a host of physical processes, including particle acceleration and plasma heating, and involves all layers of the stellar atmosphere Gyrosynchrotron radiation while they are trapped in the magnetic flaring coronal loop. time-scale of the event relates to the time-scales for the acceleration of electrons, their injection into the coronal loop, and the trapping time DG CVn binary sep ~0.2 arcsec, distance 18 pc, age ~30 Myr, detected in past radio surveys at few mJy Fender et al. (2015) Gemma Anderson, Transient triggering with AMI (ASA 2016)

LMXB V404 Cyg outburst – 15 June 2015 26 yrs quiescence AMI observing <2 hrs Bright radio flare >2.5 Jy! ×1000 charge in variability! Monitor daily, sometimes for up to 8 hours with AMI, for the next ~3 weeks AMI/ALARRM team Fender et al. in prep Gemma Anderson, Transient triggering with AMI (ASA 2016)

AMI GRBs Catalogue 139 (132 Swift) AMI observed GRBs ~871 observations <1 hr to ~90 days post-burst 90.2 days worth of observing time Not including weather affected ~20% observations 12 (11 Swift) confirmed AMI detected GRBs GRB 120326A GRB 130427A GRB 130702A (discovered Fermi) GRB 130907A (Fermi LAT detected) GRB 140304A GRB 140703A GRB 140713A (Dark Burst) 5 radio GRBs discovered with AMI! 4 strong radio GRB candidates 4 coincident steady sources (host galaxies) 7 known 5 unknown 3 candidates 4 steady sources Gemma Anderson, Transient triggering with AMI (ASA 2016)