Download - Status of Point Source Searches

ICECUBE Collaboration meeting, Berkeley 19.3.05 - 23.03.05 Markus Ackermann

Status of Point Source Searches

Markus Ackermann for

Elisa Bernardini, Elisa Resconi, Tonio Hauschildt and Markus Ackermann


Overview

Status of (time variable) point source searches

A Multi-wavelength comparison

B Sliding window flare search

C 1ES1959+650

D Future prospects

(E Online filtering changes 2005 )


Multi-wavelength comparison

• Use information from observations of the electromagnetic spectrum to define states of high activity for a source.

• If EM & neutrino emission correlated better S/N ratio

• Defined high state by:AGN x-ray (ASM/RXTE)

Microquasar radio (Ryle)

Double peak structure in AGNs: high TeV emission high x-ray emission

TeV photons & neutrinos are produced simultaneously in pp and p interactions


Multi-wavelength comparison

• very limited TeV- measurements

• x-ray all-sky monitor provides continuous data

• high state: x-ray luminosity > L

• L defined by optimizing S/sqrt(N) ratio

(S=integr. luminosity, N=duty cycle)

arbitrary relative scaling


Orphan flares

• Only one orphan flare known (1ES 1959+650, MJD 52429)

• very short duration

• NOT included in high state period defined by x-ray luminosity

• independent test was taken into consideration

• rejected for low detection probability (short flare duration)


Results of the Multi-wavelength comparison

Source EM light curve source

Livetime in periods of

high activity

Nr. of events in

high state

Expected background (high state)

Expected background

(4 years)

Markarian 421 ASM/RXTE 141 d 0 1.63 9.44

1ES1959+650 ASM/RXTE 283 d 2 1.59 4.67

Cygnus X-3 Ryle Telesc. 114 d 2 1.37 9.86


Results of Multi-wavelength comparison

• No significant excess found in high state periods• Limit on x-ray/neutrino-ratio can be calculated for the

selected AGN’s

• Full results of this analysis can be found on a dedicated web page: www.ifh.de/nuastro/

• Will be reported in dedicated paper


Search for Neutrino flares

• Method presented in Uppsala & unblinding proposal

• event times for 12 sources unblinded• 2000-2003 point source data sample used • Window size defined via detection probability investigation• Calculation of significance for cluster with highest multiplicity

in sliding window.

events

time

sliding window


Search for neutrino flares

Yellow BoxSliding Window containing event cluster with highest multiplicity

Brown Error barsexpected background for 40 days

Blue linesTime of AMANDA events


Results of neutrino flare search

Highest multiplicity found in any search window: 2 events

Source Total Nr.

Events (4y)

Total

Backgr. (4y)

Search window

Nr. of doublets

Probability for BG fluctuation

Markarian 421 6 5.58 40 days 0 Close to 1

1ES1959+650 5 3.71 40 days 1 0.34

3EG J1227+4302 6 4.37 40 days 1 0.43

3EG J0450+1105 6 4.67 40 days 1 0.47

QSO 0528+134 4 4.98 40 days 0 Close to 1

QSO 0235+164 6 5.04 40 days 1 0.52

Cygnus X-1 6 5.04 20 days 0 Close to 1

Cygnus X-3 6 5.04 20 days 0 Close to 1

GRS 1915+105 6 4.76 20 days 1 0.32

3EG J1828+0142 3 3.32 20 days 0 Close to 1

3EG J1928+1733 7 5.01 20 days 2 0.35

GRO J0422+32 5 5.12 20 days 0 Close to 1


Results of neutrino flare search

• No significant event cluster found in sliding windows for the selected sources

• Easy test for event clusters with relatively low trial factor

• Full results of this analysis can be found on a dedicated web page: www.ifh.de/nuastro/

• Included in 2000-2003 point source paper draft


but afterwards…

• comparison of the event times of 1ES1959+650 with reports on TeV gamma ray flares of the source reveals that 3 of 5 events are close to its only reported period of strong TeV flare activity in 2000-2003

• detailed investigation of these events & TeV light curves


The multi-wavelength campaign May 2002-Aug 2002

TeV (WHIPPLE,HEGRA)

X-ray (RXTE/PCA)

Optical

Radio

• Triggered by WHIPPLE observation

• TeV flux up to several Crab(average flux ~ 0.05 Crab)


The AMANDA events

AMANDA – 1ES1959+650

E> 600GeV

WHIPPLE E> 2TeV


Looking in a larger bin

• 4.5 deg (95% limit of MC point spread function)• 8 events in a window of 90 days • expected from background : ~ 1.3 events (in 90 days)

Period of multi-wavelength campaign


AMANDA events in larger bin

WHIPPLE

Event time / MJD Event time / MJD Event time / MJD

52394.0 0.50 52440.8 2.90 52460.3 1.26

52410.7 3.84 52445.2 4.37 52481.6 4.11

52429.0 1.63 52445.8 3.36

WHIPPLE


Interpretation & Outlooks

• No way to state a significance for this “unblind” analysis.

Chance probability: P(bg) = 3 103

• Even the most “unblind” chance probabilities one could calculate are far from 5

• Nevertheless, even though we cannot claim any discovery it is very encouraging for future analyses

• Could we trigger Gamma Ray Telescope “target of opportunity” observations with neutrinos in the future ?


Future plans for 1ES 1959+650

A Statistically independent sample for 1ES 1959+650• remove events which passed our quality cuts • generate & optimize new sample with new cuts • another ‘blind’ search may be possible with a quantitative

statistical statement

B Correlation analysis for neutrino & gamma light curves • interesting method in literature (Edelson et al., ApJ 333,646-659)

• needs adaptations for our case• still discussing technical issues


Other promising flares

• Promising events happened in 2004 which can be investigated when the data is processed:

• Markarian 421 possible “orphan” flare– preliminary results reported on

conferences– will be investigated further

• huge SGR 1806-20 flare– 104 times more luminous than largest

gamma ray bursts– Neutrinos could be visible in

AMANDA (Ioka et al., astro-ph/0503279)– 20 deg below horizon, but tflare

~ 0.1sHurley et al., astro-ph/0502393


Task for future analyses

• Refine the multi-wavelength approach– is it possible to include (x-ray) spectral information in

period selection criteria ? – define standards (significance thresholds) for a

detection/indication

• Refine the flare search approach– work around the arbitrary fixed window size– different type of optimization for flare search data sample?


A Neutrino alarm using online filtering

Goal: Trigger ray-telescope observation of a promising source with AMANDA neutrinos

(possibly increased detection chance for orphan flares)

• Online filtering chain completed this year at pole

(details at the end of talk)

• Neutrino events can be filtered out in (nearly) real time(events filtered ~1h after detection)

• background for standard PS cuts: ~ 1-2 ev/year

• Telescopes could be notified with very short time lag

(if SN Iridium modem is used)


A Neutrino alarm / Current status

• Small PERL script can do a “standard” analysis of data files:– Zeuthen PS cuts are applied to online L3 filtered data.– RA is scrambled for passing events– e-mail message containing the event data is sent (to me)

FOUND EVENT 3676680 AZIMUTH RANDOMIZED

YEAR 2005 GPSDAY 8 MJD 53442 GPSTIME 56439.420513000 ZENITH_PANDEL 121.85 AZIMUTH_PANDEL 74.6655344017576 DEC_PANDEL 31.85 RA_PANDEL 4.12448774588978

LLHDIFF_BAYES_PANDEL 34.737 PHIT_SMOOTHNESS 0.253269 PARABOLOID_RESOLUTION 2.154475525 DISTANCE FROM Makarian-421 54.0452288086954 DISTANCE FROM 1ES1959+650 84.0200808312958

MAIL WAS SENT 66 MINUTES AFTER EVENT


A Neutrino alarm / Current status

• integration into online filtering chain at pole trivial

• should be tested at pole to investigate:– false alarm rate– quality of passing events – time between event & e-mail


Online filtering changes 2004/2005

• NEW data stream: high quality up-going muon events.– similar to L4 from offline filtering– Additional Smoothness cut: abs(S_Phit)<0.4– ~500ev per day– contains all fits used in our PS analysis

(Pandel, Bayesian, Paraboloid, Topf) – can be easily used to get the “daily neutrinos”

• TWR merging now done by Sieglinde


The sad part….

Do not use online filtered data from 2005

• No final T0-calibration for 2005 available (muon-T0 missing)• Running on 2004 T0 constants, update to 2005 preliminary

constants after the meeting• Not reliable because many gains/thresholds were changed

Will be updated as soon as final calibration is available


Summary

• Flare & Multi-wavelength searches unblinded, no detection of a neutrino source

• neutrinos for 1ES1959+650 show very interesting correlation to WHIPPLE TeV light curves.

• Still many things to complete on the time variability analyses

• 2004 data is very promising with new interesting flares