Photon Assisted Neutrino Signals

Cosmological Signals from Cosmic Dawn Aspen, USA

8 February 2018

Albert Stebbins Theoretical Astrophysics Fermilab “the neutrino lab”

fast time domain multi-messenger astronomy

Dynamic Neutrino Sky 10’s of MeV / mostly core collapse SNe

Speed up 45x

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E n@MeVD

m1 = 60 m2 = 61 m3 = 78 @mevD Rk = 2.0 Gpc

Kinematic time Delays from Neutrino Mass

For very short neutrino bursts the different mass eigenstates separate

Kinematic Radial Distance

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0.51

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distances[Gpc

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“Cosmic Dawn” 10-100 MeV Neutrino SourcesNeutron star major life events: • birth - core collapse supernova • marriage - binary neutron star coalescence • death - collapse to black hole or eaten by black hole Most powerful source known: ≲1053ergs in ν’s in seconds • apart from gravity wave bursts

• fluctuations in neutrino flux are large on short timescales e.g. in 10 minutes

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#IBD = 2+ (80320) 1 (14962) 0 (9218) Mwater = 5.Tton T = +1h00m kTν = 5.MeV

• neutrino bursts occurs frequently >20Hz e.g. in 1 hour

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This “diffuse neutrino background” dominates human/terrestrial/solar neutrinos at these energies

confusion not too bad evenw/ no angular resolution

Nearly ideal timescales for cosmological Neutrino Bursts

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Δtkin (sec)

Neutrino bursts last • ~0.1-10 sec depending on details • supernovae w/o black holes formation last ~10sec • kinematic time delays are ~minutes at cosmological distances e.g. for inverse beta decays induced by population of core collapse SNe

Riddle: How can neutrino telescopes be both the smallest

and largest telescopes?

but, to obtain the results in the video one only needs a collecting area of 2.5cm2 .

The collecting area of existing neutrino telescopes operating at E~10 MeV have apertures 107 x smaller than this.

Ice Cube is arguably the largest astronomical telescope: ~1 km3

resolution: neutrino telescopes are almost completely transparent to neutrinos.

Ultimate: cm2 / 1012 ton ν telescope

1 km3 H20 like IceCube

Soon: Hyper Kamionkande: 106 ton ν telescope

Distributed Gigaton telescopes• NB IceCube is already a gigaton class telescope - but

limited instrumentation makes unable to detect energies as low as 100MeV.

• Other uses:

Learned 2008

Neutrino Astronomy Needs Help!• Neutrinos are cross-sectionally challenged!

• One needs to detect multiple photons from individual bursts to make use of the time-domain features.

• Before one gets to the gigaton scale one can study the overall diffuse background with ν telescopes and can not make use of time-domain to isolate sources.

• If other emission (EM/GW) associated with neutrino bursts can be detected with high time localization (seconds) one can correlate with neutrinos.

• Long/short duration GRBs (SNe/NS+NS mergers) can be used in this way. one can use megaton scale detectors over decades to detect these neutrinos.

• FRBs might also work.

• These methods work over only for relatively nearby sources (not Cosmic Dawn).

Nearby bursts dominate DNSB

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IBDêgigatonêdecadeêDln@zD

CC: ¯ fi NS CBC: NS + NS fi NS CC during CBC

These events occur rarely.

SUMMARY• The neutrino sky is dynamic and theoretically a great probe of “cosmic dawn”

• especially through core collapse supernova.

• Order unity temporal fluctuations on the minute timescale can isolate individual sources

• (no angular resolution needed)

• Neutrinos come with their own distant indicators via timing.

• Neutrinos are hard detect and need enormous (and expensive) detectors.

• Neutrino telescopes are steadily growing in size - we may get there some day?

• Even with (10) megaton class detectors one can make use of temporal fluctuations if one has other temporal signals.

• GRBs (SNe) will work over time (decades) - but decreases useful event rate enormously.

• FRBs could give you a boosted event rate w all sky detection if they are accompanied by neutrino bursts.

Is DSNB the main background?• It is believed that Gadolinium doped water Cerenkov

detectors can reduce 12-30 MeV background (mostly atmospheric ν’s) events below the Diffuse Supernova Neutrino Background (DSNB).

• The DSNB is the irreducible background for ν’s associated with transients.

• Gadolinium plus FRB timing reduces backgrounds to FRB associated ν’s to negligible levels for FRBs with z≲0.2.

• However to get a significant signal in a decade one requires extremely large detectors (> 1 megaton).