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Multi-Channel Astrophysics
& Cosmology
at the Highest Energies
Vasiliki Pavlidou
University of Chicago
Outline
o The need for multi-channel studies in High-Energy
Astrophysics
o The next 10 years of High-Energy Messengers
o What to look forward to:
 Breaking the degeneracy: AGNs, SNRs, GRBs, UHECRs
 Serendipitous discoveries
 Astrophysics with high-energy observations:
measuring cosmic star formation
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
Why multi-channel and multiwavelenght?
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
Multi-channel and multi-wavelength
studies:
a must for high-energy astrophysics
NRAO 530 / 2EG 1735-1312
o Tested and tried:
low energy Markarian
photons
+ high energy observations
501
or GeV + TeV photons
 source identifications
(GRBs, gamma-ray loud blazars, pulsars, PWN)
 better monitoring of system variability, local conditions
 large spectral dynamical range, better tests for emission
models
Pian, Vacant, Tagliaferri, Ghisellini, Maraschi, Treves,
Bower, Backer, Wright, Forster, Aller, & Aller 1997
Urry, Fiore, Giommi, Palazzi, Chiappetti, & Samburna 1998
Reimer & Funk 2006
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
High-Energy observations in the Next
Decade
o GLAST: continuous full-sky coverage in GeV gamma
rays
o Ground-based TeV telescopes: (CTA/AGIS/HAWC):
full sky accessible in TeV gamma rays, high angular
resolution
o IceCube, KM3NeT: continuous full-sky coverage in
TeV neutrinos
o Auger South + North: continuous full-sky coverage
in UHE CRs, photons, neutrinos
o Perks: LIGO, LISA, JWST
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
The future: 1. Breaking the degeneracy
o
o
o
o
What is the origin of cosmic rays?
AGNs, SNRs: hadronic or leptonic processes?
AGNs, leptonic emission: SSC or EC?
A success
story
AGNs,
GRBs: how
high do they go? (GLAST, CTs,
from cosmology
UHECRs)
o What is making the highest energy particles?
Top-down or bottom up? UHECRs, GLAST
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
The future: 2. Serendipitous discoveries
o XXX2017: winning the jackpot
nearby transient (merger between compact objects ?)
 GLAST detects it as a very bright transient gamma-ray source.
 Follow up with Cherenkov detectors - high angular resolution.
 LIGO detects gravitational wave emission; nature of progenitor
known at high confidence
A success story
 Low-energy multi-wavelength campaign
from neutrino
 Neutrino detectors pick up the -spike
astrophysics
 Auger picks up the UHE particle signature (time broadening
small and understood!)
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
The future: 3. Low-E astrophysics
with high-E observations
o The Cosmic Star Formation Rate: how much gas mass
is converted to stars per unit time per unit cosmic volume
o An essential measure of: baryonic energy production,
feedback processes in structure formation
o Contributes to reionization
o Links all of the messengers of interest!
o Traditional measures: SF makes stars - young stars emit
in UV, IR
compilation by Hopkins & Beacom 2006
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
The SF - high-energy connection
Ave, Busca,ray
Malkan,
Olinto,
o Star Formation -> Supernovae ->Allard,
Cosmic
acceleration
Parizot, Stecker & Yamamoto 2006
> interaction with ISM -> , 
o Star Formation -> gamma-ray bursts -> UHECRs?, , 
o Star Formation -> Background starlight (EBL) -> interaction
with: , UHECR
 EBL imprinted on spectra of: individual -ray sources, -ray
Blain & Natarajan 2000
Kalashev, SemikozUHECRs
& Sigl 2007galaxies (VP & Fields 2002)
background,
Starforming
Stecker
Unidentified sources
(VP, 1999
Siegal-Gaskins, Fields, Olinto & Brown 2007)
 Cosmogenic Blazars
,  (VP & Venters 2007)
EGRET gamma-ray background, conservative (Strong et al 2004)
Maximal EGRET gamma-ray background (Sreekumar et al 1998)
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
How do we utilize this connection?
o Until now: use knowledge of CSFR to predict
signal/effects for high-energy telescopes
o The future: concurrent high-E observations in
different channels allow inversion of the problem: use
observations of high-E signal/effects to constrain
CSFR
o Uncertainties: significant, BUT largely uncorrelated
with uncertainties of low-E methods
Strigari, Beacom, Walker & Zhang 2005
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
CSFR teaser: 15 yrs from now
o GLAST has detected:
 CSFR peak in gamma-ray background @E ≈ 1 GeV
 pileup/suppression of gamma-ray background @ E20GeV
 unabsorbed spectra of hundreds of low-z blazars
+ improved IR
CSFR observations
by
o GLAST+Cerenkov
Telescopes
have detected:
Spitzer, JWST
 EBL absorption signatures in high-E tail of hundreds/thousands of
+ good
high-z
blazarsampling
spectra of GRB afterglows,
strong constraints
of z-distribution of GRBs
o IceCube/KM3NeT
have detected:
 Cosmogenic neutrino signature
o Auger has determined:
Prodanovic, VP & Fields preliminary
 Spectrum, composition, sources and their cosmological evolution,
acceleration mechanism of UHECRs,
 Exact shape of GZK
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17
Conclusions
o Multi-channel, multi-wavelength observations give
unique new insight into high-E astro
o The time to do high-energy astrophysics is now:
 Combined data from different upcoming instruments
+ improved low-E observations => unprecedented
possibilities for: multi-channel, multi-wavelength monitoring
of the high-E sky, resolution of model degeneracies
 A new era: high-E observations can quantitatively map the
cosmic history of baryonic energy generation and feedback
Vasiliki Pavlidou
Ultra high energy photons, protons and neutrinos
Penn State, May 17