News from the very-high-energy sky with H.E.S.S - Andreas Zech LUTH, Observatoire de Paris for the H.E.S.S. Consortium - CERN Indico
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
News from the very-high-energy sky
with H.E.S.S.
Andreas Zech
LUTH, Observatoire de Paris
for the H.E.S.S. Consortium
The H.E.S.S. array in 2019
* 5 operating telescopes (4 x 12 m with upgraded cameras, 1 x 28 m)
* energy threshold mono : ~30 GeV , stereo : ~ 80 GeV
* only Imaging Air Cherenkov Telescope array in the Southern Hemisphere
A. Zech for H.E.S.S., Blois 2019 2
News from the Galactic sky
A. Zech for H.E.S.S., Blois 2019 3
H.E.S.S. Galactic Plane Survey
~2700 hr of observations,
sensitivity better than
2% of Crab nebula flux
extended and point-like
sources
78
Astronomy & Astrophysics special issue (2018)
H.E.S.S. phase-I observations of the plane of the Milky Way
A. Zech for H.E.S.S., Blois 2019 4
H.E.S.S. Galactic Plane Survey
~2700 hr of observations,
sensitivity better than
2% of Crab nebula flux
extended and point-like
sources
A. Zech for H.E.S.S., Blois 2019 5
HESS J1826-130 - an extreme accelerator
●
unidentified TeV emitter in the Galactic Plane
●
analysis challenging due to nearby bright PWN
●
200 hr of observation time led to discovery of
very hard spectrum
( dN/dE ~ E-1.78, cutoff at about 15 TeV )
two scenarios :
●
e+ / e- from nearby PWN
-> Inverse Compton emission on
ambient photons ?
●
cosmic rays from the progenitor SNR
of PWN HESS J1826-137
-> pion prod. on molecular clouds ?
-> PeVatron candidate ?
A. Zech for H.E.S.S., Blois 2019 6
News from the extra-galactic sky
A. Zech for H.E.S.S., Blois 2019 7
HESS-I legacy extragalactic survey
●
re-analysis of ~a decade of data on the
extragalactic sky ( Galactic regions cut )
●
> 6% of egal. sky covered in ~2600 hr
●
re-detection of 24 sources (6 variable)
●
184 3FGL objects in field of view
●
for 11 objects, HESS upper limits are
below 3FGL extrapolation
-> intrinsic spectral turnovers
●
release of source catalog and maps in
the near future
A. Zech for H.E.S.S., Blois 2019 8
Centaurus A : spectrum
●
213 hr of HESS + 8 yr of Fermi-LAT
●
spectral hardening in Fermi-LAT data
around 2.8 GeV at 4 σ
●
no indication for variability
●
disfavours one-zone SSC model
p+
synch
e-
●
two-zone SSC emission ? synch
( e.g. HESS paper Abdallah et al. 2018) preliminary
emission
from
●
one-zone lepto-hadronic emission ? secondaries
( e.g. G. Fichet de Clairfontaine,
Master thesis )
A. Zech for H.E.S.S., Blois 2019 9
Centaurus A : jet
●
extended gamma-ray emission above
240 GeV : elliptical Gaussian preferred
at TS = 19.4 over point source
●
aligned with the kpc-scale jet
●
best-fit elliptical Gaussian (white contour)
shows extension of ~ 3 kpc
(21 cm)
upscattering of
starlight along the
kpc jet ?
kpc
Hardcastle & Croston, 2011
A. Zech for H.E.S.S., Blois 2019 10Transients
regular follow-up of multi-wavelength and multi-messenger alerts :
- AGN flares and Galactic transients
in 2019 : observation of 10 different AGN, 1 ATEL (PG 1553+113)
upper limits on 10 core-collapse supernovae
- GRBs and FRBs
2018/19 : observation of 11 GRBs
- high-energy neutrinos
alerts from Antares and IceCube
IceCube event 170922A
- gravitational waves
Advanced LIGO/VIRGO O1 run : coverage of several alerts - including GW170817
Advanced LIGO/VIRGO O3 run : ongoing
A. Zech for H.E.S.S., Blois 2019 11observation of a gravitationally lensed blazar
●
PKS 1830-211 is a gravitationally
lensed FSRQ at z=2.5
Fermi flare
●
HESS observations triggered by
Fermi-LAT alert on July 27, 2014 EBL
EBL
to search for delayed emission Gilmore
Franceschini
Fermi
simultaneous
with HESS HESS
●
HESS search for the delayed flare image :
no significant detection
●
future detections possible
-> distinguish between EBL models
-> pinpoint spatial origin of HE emission
A. Zech for H.E.S.S., Blois 2019 12AGN flares : focus on 3C 279
June 2015 flare
●
triggered by Fermi -> significant detection
during 2nd night of observations
●
emission region outside of the broad line region
●
one-zone leptonic and hadronic models not
satisfactory
2018 flares
January : flare detected above 60
GeV with a factor ∼4 increase in
luminosity from one night to the other
June : mono & stereo data under
analysis
A. Zech for H.E.S.S., Blois 2019 13The future of the H.E.S.S. array
fall 2019 :
replacement of the CT5
camera (28m telescope) with from 2020 on :
a CTA-type “FlashCam” H.E.S.S. continues, subject
to 3-yr reviews, until CTA
Following the 2017 upgrade operations begin
of CT1-4 cameras with CTA
NECTArCam electronics. -> scientific exploitation
( transients, legacy
projects, ...)
-> prototyping for CTA
A. Zech for H.E.S.S., Blois 2019 14Conclusions
- legacy data sets : Galactic Plane Scan , Extragalactic Survey
- ToO observations take an increasingly important place.
- prototyping for CTA :
-- H.E.S.S. is the only hybrid Cherenkov array
-- introducing “NECTAr-cam” , “FlashCam” CTA technology
-- beginning operations under moonlight
-- towards a public data format and analysis tools
A. Zech for H.E.S.S., Blois 2019 15A. Zech for H.E.S.S., Blois 2019 16
the Vela pulsar
●
40 hr of observations with HESS II
CT5 mono analysis above 10 GeV
+ 8 yr of Fermi-LAT data
●
only the 2nd detection of pulsed emission
with Cherenkov telescopes
●
peak spectrum curved in 10 - 100 GeV
range, with sub-exponential cutoff
●
excellent agreement between Fermi
and HESS energy scales
●
evidence for a hard spectral component
beyond 100 GeV before the peak !
see also arXiv1905.07975 for joint H.E.S.S.
& Suzaku observations of the Vela X PWN
A. Zech for H.E.S.S., Blois 2019 17Vela pulsar - emergence of LW2 component
A. Zech for H.E.S.S., Blois 2019 18cosmic-ray electrons
analysis of ~1200 hr observations in
extragalactic target fields
( total sky coverage of 0.8 sr )
- electron spectrum up to 20 TeV
- upper limits on dipole amplitude
-> strong constraints on scenarios with a
dominant source, such as the SNRs Vela,
Cygnus Loop or Monogem
A. Zech for H.E.S.S., Blois 2019 19an attempt at modelling TXS 0506+056
A. Zech for H.E.S.S., Blois 2019 20observations of core-collapse supernovae
A. Zech for H.E.S.S., Blois 2019 21A. Zech for H.E.S.S., Blois 2019 22
You can also read
