A newly discovered VHE gamma-ray PWN candidate around PSR J1459-60

Observations of the Galactic Plane performed by the H.E.S.S. telescope array have revealed a significant excess at very-high-energies (VHE; E>0.1 TeV) from the direction of PSR J1459-60, a rather old gamma-ray pulsar (64 kyr) with a spindown energy of ~10^36 erg/s, discovered by the Fermi/LAT satellite in high-energy (HE) gamma-rays. The X-ray pulsar counterpart has been recently detected using the Suzaku satellite. In this contribution, we present the discovery of a new VHE gamma-ray source, including morphological and spectral analyses. Its association with the gamma-ray pulsar in a PWN scenario will be discussed

The near-infrared detection of PSR B0540-69 and its nebula

The ~1700 year old PSR B0540-69 in the LMC is considered the twin of the Crab pulsar because of its similar spin parameters, magnetic field, and energetics. Its optical spectrum is fit by a power-law, ascribed to synchrotron radiation, like for the young Crab and Vela pulsars. nIR observations, never performed for PSR B0540-69, are crucial to determine whether the optical power-law spectrum extends to longer wavelengths or a new break occurs, like it happens for both the Crab and Vela pulsars in the mIR, hinting at an even more complex particle energy and density distribution in the pulsar magnetosphere. We observed PSR B0540-69 in the J, H, and Ks bands with the VLT to detect it, for the first time, in the nIR and characterise its optical-to-nIR spectrum. To disentangle the pulsar emission from that of its pulsar wind nebula (PWN), we obtained high-spatial resolution adaptive optics images with NACO. We could clearly identify PSR B0540-69 in our J, H, and Ks-band images and measure its flux (J=20.14, H=19.33, Ks=18.55, with an overall error of +/- 0.1 magnitudes in each band). The joint fit to the available optical and nIR photometry with a power-law spectrum gives a spectral index alpha=0.70 +/-0.04. The comparison between our NACO images and HST optical ones does not reveal any apparent difference in the PWN morphology as a function of wavelength. The PWN optical-to-nIR spectrum is also fit by a single power-law, with spectral index alpha=0.56+/- 0.03, slightly flatter than the pulsar's. Using NACO at the VLT, we obtained the first detection of PSR B0540-69 and its PWN in the nIR. Due to the small angular scale of the PWN (~4") only the spatial resolution of the JWST will make it possible to extend the study of the pulsar and PWN spectrum towards the mid-IR.Comment: 11 pages, 10 figures, Accepted for publication on Astronomy and Astrophysic

UV Emission line shifts of symbiotic binaries

Relative and absolute emission line shifts have been previously found for symbiotic binaries, but their cause was not clear. This work aims to better understand the emission line shifts. Positions of strong emission lines were measured on archival UV spectra of Z And, AG Dra, RW Hya, SY Mus and AX Per and relative shifts between the lines of different ions compared. Profiles of lines of RW Hya and Z And were also examined. The reality of the relative shift between resonance and intercombination lines of several times ionised atoms was clearly shown except for AG Dra. This redshift shows a well defined variation with orbital phase for Z And and RW Hya. In addition the intercombination lines from more ionised atoms and especially OIV are redshifted with respect to those from less ionised atoms. Other effects are seen in the profiles. The resonance-intercombination line shift variation can be explained in quiescence by P Cygni shorter wavelength component absorption, due to the wind of the cool component, which is specially strong in inferior conjunction of this cool giant. The velocity stratification permits absorption of line emission. The relative intercombination line shifts may be connected with varying occultation of line emission near an accretion disk, which is optically thick in the continuum.Comment: 14 pages, 11 figures, to appear in A&

Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301-243 with H.E.S.S.

The active galactic nucleus PKS 0301−243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV 100 GeV) by the High Energy Stereoscopic System (H.E.S.S.) from observations between September 2009 and December 2011 for a total live time of 34.9 h. Gamma rays above 200 GeV are detected at a significance of 9.4σ. A hint of variability at the 2.5σ level is found. An integral flux I(E > 200 GeV) = (3.3 ± 1.1stat ± 0.7syst) × 10-12 ph cm-2 s-1 and a photon index Γ = 4.6 ± 0.7stat ± 0.2syst are measured. Multi-wavelength light curves in HE, X-ray and optical bands show strong variability, and a minimal variability timescale of eight days is estimated from the optical light curve. A single-zone leptonic synchrotron self-Compton scenario satisfactorily reproduces the multi-wavelength data. In this model, the emitting region is out of equipartition and the jet is particle dominated. Because of its high redshift compared to other sources observed at TeV energies, the very high energy emission from PKS 0301−243 is attenuated by the extragalactic background light (EBL) and the measured spectrum is used to derive an upper limit on the opacity of the EBL.Fil: Abramowski, A.. Universitat Hamburg; AlemaniaFil: Acero, F.. Universite Montpellier II; FranciaFil: Aharonian, F.. Max Planck Institut für Kernphysik; AlemaniaFil: Benkhali, F. Ait. Max Planck Institut für Kernphysik; AlemaniaFil: Akhperjanian, A. G.. National Academy of Sciences of the Republic of Armenia; ArmeniaFil: Medina, Maria Clementina. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; ArgentinaFil: Valerius, K.. Universität Erlangen Nürnberg; AlemaniaFil: van Eldik, C.. Universität Erlangen Nürnberg; AlemaniaFil: Vasileiadis, G.. Universite Montpellier II; FranciaFil: Venter, C.. North West University; SudáfricaFil: Viana, A.. Max Planck Institut für Kernphysik; AlemaniaFil: Vincent, P.. Université Paris Diderot - Paris 7; FranciaFil: Völk, H. J.. Max Planck Institut für Kernphysik; AlemaniaFil: Volpe, F.. Max Planck Institut für Kernphysik; AlemaniaFil: Vorster, M.. North West University; SudáfricaFil: Wagner, S. J.. Universität Heidelberg; AlemaniaFil: Wagner, P.. Humboldt Universität zu Berlin; AlemaniaFil: Ward, M.. University Of Durham; Reino UnidoFil: Weidinger, M.. Ruhr-universität Bochum; AlemaniaFil: Weitzel, Q.. Max Planck Institut für Kernphysik; AlemaniaFil: White, R.. The University of Leicester; Reino UnidoFil: Wierzcholska, A.. Uniwersytet Jagiellonski; PoloniaFil: Willmann, P.. Universität Erlangen Nürnberg; AlemaniaFil: Wörnlein, A.. Universität Erlangen Nürnberg; AlemaniaFil: Wouters, D.. CEA Saclay; FranciaFil: Zacharias, M.. Ruhr-universität Bochum; AlemaniaFil: Zajczyk, A.. Universite Montpellier II; FranciaFil: Zdziarski, A. A.. Nicolaus Copernicus Astronomical Center; PoloniaFil: Zech, A.. Université Paris Diderot - Paris 7; FranciaFil: Zechlin, H. S.. Universitat Hamburg; Alemani