Neutrino Astronomy with IceCube at the Earth's South Pole · 2018-12-28 · Earth IceCube IceCube...

Naoko Kurahashi Neilson, Drexel University 1

Neutrino Astronomy with IceCube at the Earth's South Pole

Naoko Kurahashi Neilson (Drexel University)

Yale NPA Seminar, Jan 26th, 2017


How it started....Highest energy particles observed

GeV

109eV

TeV

1012eV

PeV

1015eV

EeV

1018eV

Charged particles

Neutral particles γ ray

nucleihuman-made

(LHC)


GeV

109eV

TeV

1012eV

PeV

1015eV

EeV

1018eV

Charged particles

Neutral particles

nuclei

neutrino!

● How are neutral particles created at such high energies? The same way by us?● Can neutrinos be created the same way γ-rays are?● What are the connections between these high energy observations?● What are the most likely sources of these observed neutrinos?

γ ray

human-made(LHC)

How it started....Highest energy particles observed

High-Energy Astronomy

Producing γ rays

Inverse Compton

e-

e-

Leptonic Processes Hadronic Processes

Bremsstrahlung, etc

P + P or P + γ creates π0

π0

creates π+/- too!

Produces ν too


See deeper into sources

Learn how gamma-rays are created

Learn where cosmic-rays are coming from

Neutrino Astronomy – The Dream


Neutrino Astronomy – The Reality

Issue 1: cross section Issue 2: backgrounds

Galactic disk ~1023cm

Cross section from Gandhi et al., Phys. Rev. D 58 (1998) 093009

Atmosphere thickness 1x106cm

Earth radius 6x108cm

Observable universe ~1028cm

Naoko Kurahashi Neilson, Drexel University 12Completed in Dec 2010!


~250 people for ~40 institutions


Two Ways to Probe Neutrino Astrophysics

Goal: Resolve each spectral component in energy

Requirements: - Good energy proxy variable- Good purity in data over statistical power (need to understand all components)- Accurate estimate of energy proxy error range- Prior knowledge of characteristics of components helpful

Goal: Resolve sources (clusterings) in space

Requirements: - Good angular resolution- Good statistical power over purity (background is spatially uniform)- Accurate estimate of angular error range- Prior knowledge of potential source locations helpful

Diffuse Analyses Point Source Analyses

EarthIceCube

IceCube backgrounds are atmospheric shower components

0

● Most charged π/K decay to μ rather than e● ν produced in the same interaction, but lower cross

section● Most common bkg: μ > νμ > νe (Southern Hemisphere)

● νμ > νe (Northern Hemisphere)

● At higher energy, π/K lifetime is longer → more interact rather than decay

● μ, ν spectra softer than primary CR's

● At higher energies, charmed mesons produced● Shorter lifetime, decay products are harder spectra than

π/K decay → “prompt” flux


Diffuse Analysis 1IceCube's discovery analysis in 2013

μ Veto

μ

νμ

Could be an atmospheric muon from a CR shower

Most likely a neutrino

Science 342, 1242856 (2013)

2010-2012 (2 years of data) ● Flux assuming E-2: ~1.2 x 10-8 E-2 [/GeV/cm2/s/sr]● Best fit spectral index: -2.2

Events with interaction vertices contained inside the IceCube detector

μ Veto

μ

νμ

More likely to be neutrino events

Could be an atmospheric muon or could be a muon caused by neutrinos


The higher the energy, the better this works!

Tagging atmospheric neutrinos

The accompanying muon trips the veto! → “Self-veto”



μ Veto

μ

νμ



Science 342, 1242856 (2013)




μ Veto

μ

νμ



arXiv:1510.05223



Diffuse Analysis 2Updated veto to the discovery analysis

● Flux Level:~2.2 (E/100GeV)-2.5 10-8 [/GeV/cm2/s/sr] ● Spectral index: -2.5

IceCube Collaboration (2015) Phys. Rev. D. 91

* This was for 2010-2012 data. Update to this analysis in the pipeline


Diffuse Analysis 3A different approach: Only look below the horizon to

avoid atmospheric muon background

2009-2010 2010-2011 2011-2012 2011-2015

arXiv:1607.08006

● Flux Level:~ 0.9 (E/100TeV)-2.13 10-18 [/GeV/cm2/s/sr] ● Spectral index: -2.1


Diffuse Analyses Conclusion

● The universe emits high energy neutrinos

● Characterization in progress, but the whole picture is unclear for now

Assumptions:- one flux for whole sky- one spectral index- same flux for each flavor

Some tensions imply.....Break in the spectrum?

- difference in energy probed imply hardening- but then no Glashow events?- break and cutoff?

Spatially different flux?

90% confidence interval comparison

arXiv:1607.08006


Two Ways to Probe Neutrino Astrophysics

Goal: Resolve each spectral component in energy

Requirements: - Good energy proxy variable- Good purity in data over statistical power (need to understand all components)- Accurate estimate of energy proxy error range- Prior knowledge of characteristics of components helpful

Goal: Resolve sources (clusterings) in space

Requirements: - Good angular resolution- Good statistical power over purity (background is spatially uniform)- Accurate estimate of angular error range- Prior knowledge of potential source locations helpful

Diffuse Analyses Point Source Analyses

Through-going tracks:Collect all good quality tracks

“2008” year Old Data (40-strings detector)~37,000 events

Equatorial coordinates

Likelihood Search for a Source- Test Statistic (TS) Calculation -

Maximize the likelihood L assuming a source at point x with energy spectrum E-γ

Probability density that event i comes form a

source with spectrum γ

Probability density that event i comes form a known background energy spectrum

Total # of events# of events from sourceVaried to maximize L

Probability densitythat event i comes from a source at position x

Probability density that event i is from backgrounds

expected at position x


Point Source Analysis 1Search for cluster: all-sky and around known sources

All-sky search

Time-integrated unbinned search of hot spots in 7 years of data(4-year version Astrophys.J. 796:109,2014)

BL LacPKS 0537-441PKS 2155-304PKS 0235+1641ES 0229+200W ComaeMrk 421Mrk 501H 1426+4283C66A1ES 2344+5141ES 1959+650S5 0716+71PKS 2005-489PKS 0426-380PKS 0548-322H 2356-3091ES 1101-2321ES 0347-121

FSRQPKS 1454-354PKS 1622-297QSO 1730-130PKS 1406-076QSO 2022-0773C2793C 273PKS 1502+106PKS 0528+1343C 454.34C 38.41PKS 0454-234PKS 0727-11

GCSgr A*

NIMGRO J1908+06 HESS J1507-622 HESS J1503-582HESS J1741-302HESS J1834-087

PWNGemingaCrab NebulaMGRO J2019+37 HESS J1356-645PSR B1259-63HESS J1303-631MSH 15-52HESS J1023-575HESS J1616-508HESS J1632-478Vela XHESS J1837-0

SFRCyg OB2

SNRIC443Cas ATYCHOCen AM873C 123.0Cyg ANGC 1275M82RCW 86RX J0852.0-4622RX J1713.7-3946W28

SeyfertESO 139-G12

XB/mqso SS433HESS J0632+057 Cyg X-1Cyg X-3LSI 30Cir X-1GX 339-4S 5039

clusterHESS J1614-51


Point Source Analysis 2Stack the sources

Quasi-diffuse search (~10% of the sky at our angular resolution)

IceCube Collab., arXiv:1410.1749 (2014)

2010-2013 data

Stacking of 127 nearby bright starburst galaxies• Within z < 0.03• FFIR(60 micron) > 4 Jy• Fradio(1.4 GHz) > 20 mJy

Waxman, TeVPA ‘13

Stacking of 862 Fermi 2LAC Blazars

Astrophys.J. 796:10 (,2014)


Point Source Analyses conclusion

● No TeV sources in neutrinos (yet)

● Statistically insignificant overfluctuations come and go, but will any stick?

● MeV neutrinos still lead in number of sources (0 vs 2)

super-kamiokande

kamiokande

The Sun Supernova 1987A

*No direction, just timing


Putting diffuse and point source together

arXiv:1502.03104All-sky source flux limit

Astrophysical DiffuseFlux


Limits in terms of % of diffuse flux

Upper limit in diffuse flux

notes

Blazars ~ 17% 862 from Fermi 2nd AGN cat.Spectral index = -2.5

Nearby Starburst Galaxies ~ 8% 127 nearbySpectral index = -2

Galactic Sources

Young SNR ~ 5% 30 with no PWN or MCSpectral index = -2

Young PWN ~ 3% 10 with no MCSpectral index = -2

Galactic Plane ~14% Fermi Diffuse γ Spatial templateSpectral index = -2.5 to -2.7

GRBs ~1% 506 bursts observed Spectral index = -2 to -2.7

Astrophys.J. 796:10 (,2014), ApJ, 805, L5 (2015)


Is it time to consider....

– New (more correct? more exotic?) models of emission?

– New sources? Optical or x-ray counterparts?

– “Dark” sources? Does this require new methods?


Multi-Messenger Astronomy withNon-EM partners

Ultra-high Energy Cosmic Rays Gravity Waves

Correlation study with highest energy events from Auger and TANo correlation beyond 3.3σ

JCAP 1601 (2016) 01, 037

LIGO gravity signal and neutrino events within +/-500s


How can we increase our chances of discovering sources sooner?

Factor of 10 doesn't seem like much until you realize how old you are in 10 years vs 100 years!


IceCube's Realtime Efforts


Example: HESE-160427A , on April 27 2016


Historical Perspective: Gamma-ray AstronomyDiffuse signal → first source → catalog!

SAS-2

Diffuse celestial radiation

GSFC nasa.gov

COS-B Discreet sources

1970's

1980's

NOW

GSFC nasa.gov

Fermi 5-year data


Historical Perspective: X-ray AstronomyDiffuse signal → first source → catalog

“The Cosmic Century” M. S. Longair

Diffuse emission and Scorpius X-1 1960's

(Sun detected in x-rays 1940's)

xte.mit.edu

APOD 8/19/2000 ROSAT


IceCube Gen2 – The next generation facility for neutrino physics and astronomy at the South Pole

arXiv:1412.5106


Getting there sooner


Conclusions

● High-energy Neutrino Astronomy is becoming a reality

● Both diffuse and point source analyses are providing new information, but together they are giving us more insight

● We keep learning lessons, and have plans to get us to discovery sooner


Backups


More IceCube Jargon

40-strings (IC-40), 376 days livetime, ~50% complete59-strings (IC-59), 348 days livetime, ~50% complete79-strings (IC-79), 333 days livetime, almost complete86-strings (IC-86), 329 days livetime, complete


A pitch for optical/x-ray/gamma-ray to followups on IceCube observations

● IceCube is updating fast alert systems (GCN/ATEL) to be sent when a “significant” neutrino is seen

● The (current) best case is ~0.5 degree error circle → not great for follow-up observations

It's a lot to ask other telescopes to observe for a long time in a large area, for most likely, nothing

● But lets not forget, the upshot is huge here! Your telescopes can discover the first non-photon source in the sky!


Topologies of different event types

Through-going Track Shower

Charge Current Electron/Tau NeutrinosAll Neutral Current NeutrinosCharge Current Muon Neutrinos

Starting Track

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