Detecting Neutrino Transients with IceCube & optical Follow-up Observations Marek Kowalski Penn State, October 2007

Content Neutrino bursts: Introduction and science motivation Filtering neutrino multiplets, expected rates Optical follow up with ROTSE III & Co.

Cosmic Rays & GRBs Extragalactic Gamma-Ray Bursts:  GRBs ~ ergs x 300/yr/Gpc 3 ~ ergs/yr/Mpc 3 GRBs could provide environment and energy to explain the highest energy cosmic rays! [Waxman 95] Energy density of extragalactic CR:  CR ~ ergs/yr/Mpc 3

Credit: Meszaros & Murase MeV neutrinos at collapse TeV neutrinos from inside the star [Meszaros & Waxman, 2001] [Razzaque et al. 2003] PeV neutrinos from internal shock [Waxman & Bahcall 1997] [Gupta & Zhang, 2006] [Murase & Nagataki 2006] PeV-EeV neutrinos from flares [Murase & Nagataki 2006] EeV neutrinos from external shocks [Dermer 2001] [Waxman & Bahcall 2000] GRBs as sources of high-energy neutrinos Fireball model for long GRBs:

Testing the Supernovae-GRB connection Observation: Rate of GRBs is just ~1% of SNe Ib/c. Question: Could there be mildly relativistic jets (  of a few) inside many SNe? GRBs SNe ? Neutrinos could provide the answer: 10 Mpc: 30 neutrino events in a cube-kilometer detector! Ando & Beacom, PRL (2005); Razzaque, Meszaros & Waxman, PRL (2005). Simulation: MacFadyen (2000) Gravitative collaps of a very massive, rotating star (>25 M  ):

Constraints on Quantum Gravity  Energy (TeV) SNe  t=10 s Jacob, Piran 2006

IceCube IceCube Neutrino-Trigger day 0 day 1-10 network of optical telescopes optical SN/GRB detection Optical Neutrino Follow-up

Neutrino burst trigger Doublet background rate: 250  a day For IceCube 2 o x 2 o 100 seconds Background rate of 5 per year, but Field-of-View of 2 o x 2 o needed. Other trigger scenarios: 1.Combine -flavors:  +   e 2.Select high-energy events

optical detection

Search for transient sources: Supernova (rising lightcurve) GRB / Supernova identification Supernova lightcurves Strizinger et al. (2003)

Search for transient sources: Supernova (rising lightcurve) Gamma-Ray Burst (afterglow) Gamma-Dark Bursts (orphan afterglows) Time of explosion: GRB / Supernova identification F ~ t -1.2 GRB afterglows Kahn et al., minutes 100 seconds

Time of explosion: MK, A. Mohr, 2007 GRB / Supernova identification

Ando & Beacom flux Double Coincidence Triple coincidence ~20th magnitude detection limit (1 m) ~0.003 background Rate [arbitrary unit] Distance [Mpc] Distribution of Supernovae (simulation)

MK, A. Mohr, 2007 Supernova sensitivity Ando & Beacom PRL2005 Sensitivity can be doubled by optical follow-up!

Content Science motivation and introduction Filtering neutrino multiplets, expected rates Optical follow up with ROTSE III & Co.

Coincident atmospheric neutrinos Neutrino-Rate~ 4700/yr~ 29,300/yr Doublet-Rate~ 0.15/yr~ 5.23/yr time-window: 100 s space-window:  12 <4° weak Cuts NDir≥5, Sigma<2.5 IC9 Cuts NDir≥9, Sigma<2.5 (IC 40, cuts not optimzed so far)

Source neutrinos Cut Efficiency 5  cut = 2°  cut = 3°  cut = 4° Doublett-Condition:  12   cut

Localizing the source median, unweighted median, weighted 1) Average the two tracks in the multiplet 2)Yet better, use parabolola’s event-wise resolution for weighting: IC 40, weak cuts

Monitoring detector stability Detector stability needs to be monitored on short time scales Use of standard IceCube verification and monitoring techniques Decicated variables for burst search

Event Rate for short time window (e.g. 30 s) Bin events according direction Sky Monitor: Rates (on trigger level) Azimuth Zenith

Azimuth Zenith Sky Monitor: Deviation Significance map,

Flasher data to illustrate instability Significance map, Azimuth Zenith Thanks to Dawn Williams

Off-time window time Event time On-time window time Event time Off-source/on time: All, but the 3 closest bins On-source/off-time: Hit bin and 2 closest neighbours Zenith Azimuth Zenith Azimuth Catching Deviations

On-time window time Event time Off-source/on time: All, but the 3 closest bins Zenith Azimuth For each event, use the most significant outlier in the two maps to characterize detector. Catching Deviations worst sigma off-source, on-time Corsika MC exp. data flasher

Content Science motivation and introduction Filtering neutrino multiplets, expected rates Optical follow up with ROTSE & Co.

The data flow IceCube Northern site Iridium satellites Send alert Optical telecopes SN/GRB

4 x 0.45 m FoV: 2  x 2  rapid follow-up ROTSE-III 3a, SSO, Australia 3d, TUG, Turkey 3c, H.E.S.S., Namibia 3b, McDonald, Texas

M o Error circle: ~60% of IC40 ~80% of IC80

Primary & secondary optical follow-up Secondary follow-up with more powerful telescopes 1) Candidates confirmed or excluded with ~100% eff. 2) Spectroscopy for ID ROTSE, first generation (2008) Primary follow-up Large FoV

Conclusion Using neutrino events to trigger optical follow-up observations. Significant sensitivity improvement for SNe, and perhaps GRBs. For some cases, it’s the only way to identify the source! Robotic telescopes for follow-up observations exist and even more will come online soon.

Constructing the Doublets 31 Θ 1true Θ 1reco Θ 2reco Θ 2true Θ 1reco Θ 2reco Spacially “coincident” neutrinos Uncorrelated atmospheric neutrinos

Optical Neutrino Follow-up

Correlating every neutrino (~10 5 /a)? Mirror Area X Field of View

Correlating every neutrino (~10 5 /a)? Next generation of Wide- Field-Imagers: full sky coverage of the optical sky with 3-7 day cadence. Offline correlation of every neutrino will be possible! Mirror Area X Field of View

Analysing a ROTSE image Of the 83 objects none shows variations larger than 1 mag GRB/SN would be identified as variable object on time-scales of minutes to days 5052 objects identified Comapare to USNO2.0 reference star catalog (match to within pixel) 83 objects not in the catalog GRB afterglow, 500 s late

Estimate of detection sensitivity from stars in the field 10  detection 5  detection

Online Burst Filter and Monitor Line Fit Paraboloid Fit Level1-Preselection Coincidence Filter Events Alert Events Reconstruct incoming events with first guess Preselection to allow full reconstruction of left-over events Filter coincident events Check stability using monitoring / verification as well as custom-made tools Sky Rate Monitor IceCube Monitor Verification

ROTSE & Company Others: RoboNet, Stella … ROTSE III 4 x 0.45 m FoV: 2  x 2  rapid follow-up