IAR   05382
INSTITUTO ARGENTINO DE RADIOASTRONOMIA
Unidad Ejecutora - UE
artículos
Título:
Discovery of TeV γ-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift
Autor/es:
H.E.S.S. COLLABORATION; M.C. MEDINA
Revista:
ASTRONOMY AND ASTROPHYSICS
Editorial:
EDP SCIENCES S A
Referencias:
Lugar: Paris; Año: 2013 vol. 552 p. 118 - 132
ISSN:
0004-6361
Resumen:
Very high-energy γ-ray emission from PKS 0447-439 was detected
with the H.E.S.S. Cherenkov telescope array in December 2009. This
blazar is one of the brightest extragalactic objects in the Fermi bright
source list and has a hard spectrum in the MeV to GeV range. In the TeV
range, a photon index of 3.89 ± 0.37 (stat) ±0.22 (sys)
and a flux normalisation at 1 TeV, Φ1 TeV = (3.5 ±
1.1(stat) ± 0.9(sys)) × 10-13 cm-2
s-1 TeV-1 were found. The detection with H.E.S.S.
triggered observations in the X-ray band with the Swift and RXTE
telescopes. Simultaneous UV and optical data from Swift UVOT and data
from the optical telescopes ATOM and ROTSE are also available. The
spectrum and light curve measured with H.E.S.S. are presented and
compared to the multi-wavelength data at lower energies. A rapid flare
is seen in the Swift XRT and RXTE data, together with a flux variation
in the UV band, at a time scale of the order of one day. A firm upper
limit of z < 0.59 on the redshift of PKS 0447-439 is derived from the
combined Fermi-LAT and H.E.S.S. data, given the assumptions that there
is no upturn in the intrinsic spectrum above the Fermi-LAT energy range
and that absorption on the extragalactic background light (EBL) is not
weaker than the lower limit provided by current models. The spectral
energy distribution is well described by a simple one-zone synchrotron
self-Compton scenario, if the redshift of the source is less than z
≲ 0.4.