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SUMMARY:The Symposium of Ultra-High-Energy Gamma Rays from Supernova Remna
 nts and the Origin of Galactic Cosmic Rays
DTSTART;VALUE=DATE-TIME:20260226T040000Z
DTEND;VALUE=DATE-TIME:20260302T100000Z
DTSTAMP;VALUE=DATE-TIME:20260607T175000Z
UID:indico-event-27978@indico.ihep.ac.cn
CONTACT:liaosy@ihep.ac.cn
DESCRIPTION:Speakers: Felix Aharonian (YSU/USTC/TCRRC/MPIK)\, Zhen Cao (In
 stitute of High Energy Physics\, CAS)\nSupernova remnants (SNRs) have long
  been considered the dominant sources of Galactic cosmic rays (CRs)\, supp
 orted by energetic arguments and the paradigm of the diffusive shock accel
 eration (DSA) as a robust particle-acceleration mechanism. Over the past t
 wo decades\, observations of TeV gamma rays and nonthermal X-rays from m
 any young SNRs have confirmed that these systems with significant magneti
 c amplification can accelerate particles to beyond 1 TeV. At the same tim
 e\, these measurements revealed unexpectedly steep spectra at multi-TeV en
 ergies. The lack of ultra-high-energy (UHE\;  E>100 TeV) gamma-ray detec
 tions by LHAASO for any young SNR has initiated debates over whether SNRs 
 can truly act as PeVatrons capable of supplying CRs around and above the k
 nee. \n\nHowever\, the observed spectral steepening does not necessarily 
 imply early cutoffs (below the "knee") in the parent particle distribution
 s. Recently recognised new features of DSA\, along with current detectors'
  sensitivity limitations\, may still allow young SNRs to reach PeV energie
 s. Moreover\, the detections of UHE gamma rays from dense environments aro
 und several middle-aged SNRs - interpreted as "smoking-gun" signatures of 
 CR interactions with nearby gas complexes - provide indirect but relativel
 y strong evidence that these SNRs may have operated as PeVatrons tens of t
 housands of years ago.  Understanding the origin of UHE gamma-ray emissi
 on also benefits from coordinated multi-wavelength efforts that combine ga
 mma-ray\, X-ray\, millimeter\, and radio observations to disentangle the r
 oles of particle acceleration\, ambient conditions\, and the SNR propertie
 s.\n\nThis workshop aims to bring together experts in CR physics and SNR 
 research to examine the implications of UHE gamma-ray observations of bot
 h young and middle-aged SNRs. Using multi-wavelength data from SNRs and th
 eir environments\, participants will explore competing interpretations\, a
 ssess the physical conditions required for PeVatron activity\, and discuss
  the broader consequences for the origin of Galactic cosmic rays. \n\nWe 
 invite interested researchers to join us for an in-depth\, collaborative d
 iscussion of this central question in cosmic-ray astrophysics.\n\n\nhttps:
 //indico.ihep.ac.cn/event/27978/
LOCATION:Chengjiang\, Yuxi\, Yunnan Province\, China
URL:https://indico.ihep.ac.cn/event/27978/
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