Modeling the emission of the galactic very high energy γ-ray sources G 1.9+0.3, G 330.2+1.0, HESS J1303-631 and PSR B1259-63/LS 2883 observed with H.E.S.S

Recently, imaging atmospheric Cherenkov telescopes (IACTs) have discovered numerous new sources representing various source classes in the very high energy (VHE; E>100 GeV) sky. This work presents studies of representatives of three types of Galactic VHE emitters: the Supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0, the pulsar wind nebula (PWN) HESS J1303.631 and the binary system PSR B1259.63/LS 2883. The analysis of the H.E.S.S. data and the broadband emission modeling are presented. G1.9+0.3 and G330.2+1.0 are synchrotron-dominated SNRs whose non-thermal X-ray emission implies that intensive particle acceleration occurs at their shock fronts. This makes them promising candidates for the detection at VHEs. They were observed by the High Energy Stereoscopic System (H.E.S.S.) yielding no signs of significant VHE γ-ray emission from either SNR. The 99% confidence level upper limits on the TeV flux were determined. For an assumed spectral index of 2.5 the obtained upper limits are FG1.9(>260 GeV)<4.6 x 10-13 cm-2s-1 for G1.9+0.3 and FG330(>380 GeV)<1.6 x 10-12 cm-2s-1 for G330.2+1.0. Upper limits on the VHE emission provide constraints on the interior magnetic field in the context of a leptonic scenario and on the interstellar medium (ISM) density and cosmic-ray (CR) efficiency in a hadronic scenario. Lower limits on the interior magnetic fields were estimated at 15 μG for G1.9+0.3 and 14 μG for G330.2+1.0. In the case of the hadronic scenario, the H.E.S.S. upper limits are two orders of magnitude greater than the flux prediction. Obtained upper limits on the ISM densities are compatible with other estimates of the densities (from the thermal X-ray emission for G330.2+1.0 and from the expansion rate for G1.9+0.3). The CR efficiency cannot be constrained with the current H.E.S.S. upper limits. HESS J1303-631 is an initially unidentified H.E.S.S. source which was recently identified as a PWN associated with the pulsar PSR J1301-6305. The broadband emission of the source was modeled within a one-zone 1D stationary model yielding a magnetic field of 1.4 ± 0.2 μG and a total energy in electrons above 1 GeV of 2 x 1048 erg. This estimate of the magnetic field is of the same magnitude as the averaged line-of-sight magnetic field of ∝2 μG provided by the measurement of the pulsar's rotation measure. A magnetic field in a PWN much lower than the averaged ISM magnetic field would be difficult to explain. A low magnetic field is also expected for evolved PWNe for which the magnetic field is believed to have decreased with time. The obtained total energy in electrons yields an estimate for the pulsar birth period between 51 and 75 ms, which is in good agreement with estimations of birth periods for pulsars associated with composite SNRs. Possible extensions of the modeling towards more realistic scenarios which would take into account the time evolution and spatial distribution of the source emission are also discussed. The binary system PSR B1259-63/LS 2883 is the only TeV binary for which the compact companion is unambiguously identified as a pulsar. It consists of a 48 ms pulsar orbiting around a massive Be star. PSR B1259-63/LS 2883 was monitored by H.E.S.S. around the periastron passage on 15th of December 2010. The source was observed by H.E.S.S. in the period from 26 to 32 days after the periastron passage. A firm detection of the source was obtained. The observed flux F(>1 TeV)=(1.61±0.22stat±0.32syst) x 10-12 cm-2s-1 and spectral index Γ=2.82 ±0.25stat±0.2syst are in good agreement with results obtained during previous periastron passages. The observations were performed at similar orbital phases as around the 2004 periastron, for the first time directly confirming the repetitive behavior of the source at VHEs. H.E.S.S. observations were part of a joint multiwavelength (MWL) campaign including also radio, optical, X-ray and, for the first time, high energy (HE; E >100 MeV) observations. Fermi LAT detected a spectacular flare which had started within the period of H.E.S.S. observations. A statistical study shows that the HE flare does not have a counterpart at VHEs indicating that the HE and VHE emissions are produced in different physical processes. The modeling of the VHE emission with the model of emission generated via inverse Compton (IC) scattering of shock-accelerated electrons on the stellar photon field is done considering the HE flux as an upper limit for this emission. The modeling yields upper limits on the electron spectral parameters and the total energy in electrons depending on the assumed electron spectral index. It was shown that for indices in the range from 1.7 to 1.9 the time needed to accumulate the required total energy in electrons is smaller than the orbital period of the pulsar.