Post on 28-Dec-2015
La nascita della astronomia dei raggi cosmici?Indicazioni dall' Osservatorio P. Auger
Aurelio F. Grillo Teramo 8/05/08
The spectrum: most statistically significant from SD calibrated in energy by “hybrid” events - energy systematic error ~22 %, mostly from systematic of the FD detector (fluorescence yield, atmospheric transparency....)
Surface Detector SD
Fluorescence Detector FD
Cosmic Ray astronomy?
If UHECRs origin is astrophysical, astronomy may be possible above some x 1019 eV if particles are protons(and IG magnetic fields small)
If UHECRs origin is astrophysical, astronomy may be possible above some x 1019 eV if particles are protons(and IG magnetic fields small)
Around ~1020 eV particles can only arrive fromwithin ~ 100 Mpc (in case of GZK)
Cosmic Ray astronomy?
If UHECRs origin is astrophysical, astronomy may be possible above some x 1019 eV if particles are protons(and IG magnetic fields small)
Around ~1020 eV particles can only arrive fromwithin ~ 100 Mpc (in case of GZK)
A statistically significant correlation with sources in theGZK spere would unambiguously prove the reality ofthe cutoff (and give hints on the nature of sources)
Cosmic Ray astronomy?
The “Telescope”
- Angular resolution ~ 1 degree
- Pointing Accuracy ~ 1 degree
- Charged Messengers => deviation in mag. fields
Search for point sources:the motivation
Small magnetic deflection Only nearby sources if GZK feature ok Nearby Universe anisotropic
1 EeV =1018 eV
Regular Gal. B field
Search for point sources:the motivation
Small magnetic deflection Only nearby sources if GZK feature ok Nearby Universe anisotropic
Indication of GZK from spectrum Bounds on photons/neutrinos Acceleration favoured vs. top-down
1 EeV =1018 eV
Regular Gal. B field
Search for point sources:the method
Need to search correlations of a selected sample of events with astrophysical objects.... how and where?
Large parameter space: -- events -> Energy, angular aperture
Sources -> what sources: type, distance (z)........
Search for point sources:the method
Need to search correlations of a selected sample of events with astrophysical objects.... how and where?
Large parameter space: -- events -> Energy, angular aperture
Sources -> what sources: type, distance (z)........
Method: perform a scan in the parameters space, after having chosen sources of a given type from a catalogue
Chosen Veron-Cetty, Veron Catalogue of AGNs
Search for point sources:the method
Some definitions: p -- exposure-weighted fraction of the sky accessible to observation, covered by windows of radius ψ centred on the selected sources. P -- probability that k or more out of a total of N events from isotropic flux are correlated by chance with the selected objects at the chosen angular scale
this probability needs 'penalization' i.e. Pfin
= P/Nt (from MC)
z<0.018
Search for point sources:the strategy
Performed an exploratory scan. Eth > 4 1019 eV
z < 0.024 Of 15 events with Eth > 5.7 1019 eV,
12 correlated within with AGNs with z<0.019, while 3.2 expected with these parameters
16
3.1o
Search for point sources:the strategy
Performed an exploratory scan. Eth > 4 1019 eV
z < 0.024 Of 15 events with Eth > 5.7 1019 eV,
12 correlated within with AGNs with z<0.018, while 3.2 expected with these parameters
Further search performed with these a priori fixed parameters, ending when the probability to incorrectly reject hisotropy hypotesis < 1%
Search started May 2006, ended May 2007 when 6/8 events found correlating.
In sample May 2006 – Aug 2007 8/13 correlating P= 1.7 10-3
16
3.1o
Search for point sources:the strategy
Rescan whole dataset with improved reconstr. algorithm to fix parameters.
20 out of 27 events correlated
(a posteriori) Pfin(iso)~10-5
Search for point sources:the PAO Sky Map
Equatorial coordinates
South pole
SuperGalactic plane
Galactic plane
Search for point sources:the PAO Sky Map
CenAVirgo
AGNs from VC-V catalogue
If region of Galactic plane excluded, 19 out of 21 events do correlate
PAO events
Search for point sources:the PAO Sky Map
CenAVirgo
AGNs from VC-V catalogue
Leiden – Argentine – Bonn Hydrogen Survey
PAO events
Search for point sources:the PAO Sky Map
Both for real events and simulated sets of same size, either isotropic or source
Search for point sources:the PAO Sky Map
AGNs: sources or tracers??No significant correlation (yet) with Abell,REFLEX, NORAS catalogues of clusters of galaxies, nor starburst radio galaxies
Search for point sources:the PAO Sky Map
AGNs: sources or tracers??No significant correlation (yet) with Abell,REFLEX, NORAS catalogues of clusters of galaxies, nor starburst radio galaxies
Search for point sources:the PAO Sky Map
AGNs: sources or tracers??No significant correlation (yet) with Abell,REFLEX, NORAS catalogues of clusters of galaxies, nor starburst radio galaxies
Search for point sources:the PAO Sky Map
The GZK “horizon”
Indication of the need of energy shift?Too early, exclude other selection effects (foreground, bias of method..)
Search for point sources:the PAO Sky Map
Magnetic fields
Extragalactic (irregular)
B rms L c10−9 G Mpc
Possibly Some open issues:-- Statistic: 27 events E> 5.7 1019 eV. One more year of data will double N.
Birth of (nuclear) Cosmic Ray Astronomy?
Possibly Some open issues:-- Statistic: 27 events E> 5.7 1019 eV. One more year of data will double N.-- Energy: at 5.7 1019 eV GZK Horizon ~ 200 Mp > 75
upward shift of energy calibration consistent with sistematic error can reconcile
Birth of (nuclear) Cosmic Ray Astronomy?
Possibly Some open issues:-- Statistic: 27 events E> 5.7 1019 eV. One more year of data will double N.-- Energy: at 5.7 1019 eV GZK Horizon ~ 200 Mp > 75 but...
upward shift of energy calibration consistent with sistematic error can reconcile-- Type of particles: some hint of heavy nuclei, larger deviation in GMF
Birth of (nuclear) Cosmic Ray Astronomy?
We are probably at a turning date for Cosmic Ray Astrophysics Sources of Cosmic Rays may have been detected, although their real identity
still unclear The Greisen-Zatsepin-Kuzmin feature has been probably detected
Conclusions?
We are probably at a turning date for Cosmic Ray Astrophysics Sources of Cosmic Rays may have been detected, although their real identity
still unclear The Greisen-Zatsepin-Kuzmin feature has been probably detected
Conclusions?
We are probably at a turning date for Cosmic Ray Astrophysics Sources of Cosmic Rays may have been detected, although their real identity
still unclear The Greisen-Zatsepin-Kuzmin feature has been probably detected
Conclusions?
We are probably at a turning date for Cosmic Ray Astrophysics Sources of Cosmic Rays may have been detected, although their real identity
still unclear The Greisen-Zatsepin-Kuzmin feature has been probably detected
A very interesting future is approaching!!
Conclusions?
Search for point sources:the PAO Sky Map
Magnetic fields
Problem not serious (yet!) also: non correlating events chance correlating events
Preliminary!!
CenA
Search for point sources:the PAO Sky Map
Preliminary!!
No distinctive feature of correlated AGNs identified. AGNs: sources or tracers?