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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
3
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
4
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
5
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
6
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
7
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
8
(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
9
(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
11
● 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
12
● 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
13
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
14
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
15
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
16
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
18
● 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
19
● 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
21
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
22
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
23
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
24
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
25
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
26
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
27
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
28
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
29
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
30
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
31
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
32
Down-Going Low-Zenith UHEν Results
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
33
Global UHEν Results
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
34
Global UHEν Results
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
35
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
36
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
37
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
38
Choked jets
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
39
Theoretical Predictions
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
40
Neutrinos from Cen A
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
41
CC vs NC Fisher Values
Down-going UHEνs in correlation with GW eventsMichael Schimp | Astroteilchenschule Bärnfels | October 11, 2016
42
Neutrinos vs. Photons