Down-Going UHE Neutrinos In The Pierre Auger Observatory+ Neutrino Follow-Up Of GWMichael Schimp on behalf of the Pierre

Auger Collaboration

October 11, 2016

UHE (EeV) ν Searches WithThe Pierre Auger Observatory

Fin

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Probe / constrain, e.g.● CR origin

➔ Sources (opaque sources e.g. choked GRBs)➔ Top down / bottom up scenarios

● CR composition / propagation(GZK)

● Something new?

Motivation

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Probe / constrain, e.g.● CR origin

➔ Sources (opaque sources e.g. choked GRBs)➔ Top down / bottom up scenarios

● CR composition / propagation(GZK)

● Something new?

PAO: large acceptance→Essential for UHEν search

Motivation

3000 km2

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Overview

● Low zenith● High zenith● Earth-skimming ν

τ

Follow-up of LIGO GW eventsYet only complete for 75° < θ < 95°

θ

60°

75°

90°

95°

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going UHEν Events

signalbg

@ ground: large EM μ dominated fraction

● Compare to simulation→ν identification

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going UHEν Events

@ ground: large EM μ dominated fraction

● Compare to simulation→ν identification

signalbg

Lower zenith→increasing background

→zenith dependent event selection& ν identification

by PMT trace width + reconstruction quality

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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(Low-Zenith) UHEν Identification

Fisher MVA →Input: Early stations' AoP

Stations' AoP for signal / bg

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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(Low-Zenith) UHEν Identification

Fisher MVA →Input: Early stations' AoP

Identification: 1 expected bg event in 20 years of full operation

Stations' AoP for signal / bg

GW Follow-Up

Fin

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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● No prompt PeV ν after GW150914 (IceCube, ANTARES)

● Fermi GBM detection 0.4 s after GW150914, compatible direction

GW Follow-Up—Why?

Commonly:

“BH merger→no ν!”

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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● No prompt PeV ν after GW150914 (IceCube, ANTARES)

● Fermi GBM detection 0.4 s after GW150914, compatible direction

GW Follow-Up—Why?

UHEν emission predictionsVietri, Waxman, Murase, Kotera, Silk

Commonly:

“BH merger→no ν!”

Upcoming LIGO events: probably further types!(e.g. NS mergers)

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Default neutrino analysis, but consider only

● [–500 s, +1 day] around a GW event

GW Follow-Up—How?

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Default neutrino analysis, but consider only

● [–500 s, +1 day] around a GW event

● Directional correlation→Binary decision: Is part of the 90% confidence region visible?

GW Follow-Up—How?

Visible solid angle moves during the day

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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GW Follow-Up Results (Earth-Skimming ντ + Down-Going High-Zenith)

Consider only time+directionally correlated events

No candidates→ Event number

limit + Exposure (δ)→ Limit on

emitted UHEν energy

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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GW Follow-Up Results (Earth-Skimming ντ + Down-Going High-Zenith)

Consider only time+directionally correlated events

arXiv:1602.06961:Binary BHs could produce the measured UHECR flux up to 100 EeV!→Needs ~ 3% efficiency (E

UHECR/E

GW)

No candidates→ Event count

limit + Exposure (δ)→ Limit on

emitted UHEν energy

Conclusions

Fin

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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● PAO seems well capable to measure UHE neutrinos

● No UHEν candidates so far

● Follow-up search on the published LIGO GW events unblinded→sensitive down to < E

GW

Summary

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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● Improve analysis● More sophisticated MVA● GW follow-up: Fold PAO field of view with LIGO's

confidence region

● Apply GW follow-up in low-zenith region

● “UHEν monitor”→Frequently apply predefined analyses instead of unblinding

Prospects

The End

Fin

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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GW Follow-Up Result On GW150914

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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Energy Dependence Of Diffuse Exposure (Phys Rev D 91, 092008 (2015))

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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Binned Diffuse Flux Limits (Phys Rev D 91, 092008 (2015))

Bin-wise(0.5 in log

E)

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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UHE Photon Background

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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Visible Solid Angle

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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Fluence Upper Limits

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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GW Follow-Up

No candidate in [–500 s, 1 day] around GW events→ Calculate exposure taking into account

● Time-dependent aperture(area x solid angle)

● ν-nucleon cross section + efficiencies (E,δ)

Earth-skimming ν

τ

(90° < θ < 95°)

Down-going ν

(75° < θ < 90°)

UHE neutrino follow-up of GW events with the Pierre Auger ObservatoryMichael Schimp | HAP Workshop Topic 2 | The Non-Thermal Universe | Erlangen | September 22, 2016

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GW Follow-Up

No candidate in [–500 s, 1 day] around GW events→ Calculate exposure taking into account

● Time-dependent aperture(area x solid angle)

● ν-nucleon cross section + efficiencies (E,δ)

→ Calculate upper limits on energy radiated in UHEν (δ) (E–2 spectrum)

Earth-skimming ν

τ

(90° < θ < 95°)

Down-going ν

(75° < θ < 90°)

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going Low-Zenith UHEν Event Selection

Fisher MVA →Input: Early stations' AoP

60°+-1.5°(lowest zenith

= “worst” background)

cut

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going Low-Zenith UHEν Event Selection

Fisher MVA →Input: Early stations' AoP

Identification: Fit Tail, Cut for 1 bg event in 20 years

cut

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going Low-Zenith UHEν Analysis

60°+-1.5° (most vertical = most signal-like)

cut

Found nothing→calculate limit● Feldman-Cousins, 0 signal, 0 bg expected● Stat. + syst.: Rolke & Conrad approaches ● Calculate exposure ξ

→Diffuse flux limit ~ N90%CL,upper

/ ξ

N90%CL,upper

=2.37

Other 80 %: unblinded

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Down-Going Low-Zenith UHEν Results

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Global UHEν Results

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Global UHEν Results

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Earth skimming events dominated by ντ

● ν interaction enhanced in Earths crust (producing e, μ, τ, nuclear fragments)

● Only τ can travel long distance through Earth and induce EAS (by decaying after ~ 48 km @ 1 EeV)

Earth-Skimming ντ Search

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Earth-Skimming ντ Selection

Inclination: 90° < θ < 95°● Elongated footprint ● “Ground signal speed” ~ c

Reject “muonic” events → > 60 % stations ToT triggered

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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No event after <AoP> cut → calculate exposure→ flux limit ~ event count limit / exposure

Earth-Skimming ντ Analysis

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Choked jets

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Theoretical Predictions

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Neutrinos from Cen A

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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CC vs NC Fisher Values

Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016

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Neutrinos vs. Photons