271 research outputs found

    The Spectral Energy Distribution of the High-Z Blazar Q0906+693

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    We describe further observations of QSO J0906+6930, a z=5.48 blazar likely to be detected in gamma-rays. New radio and X-ray data place significant constraints on any kpc-scale extension of the VLBA-detected jet. Improved optical spectroscopy detects absorption from an intervening galaxy at z=1.849 and raise the possibility that this distant, bright source is lensed. We combine the new data into an improved SED for the blazar core and comment on the Compton keV-GeV flux component.Comment: 10pp, 3 figures, accpeted for publication in the Astronomical Journa

    Echelle Spectroscopy of gamma-ray binary 1FGL J1018.6-5856

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    We observed the Fermi-discovered gamma-ray binary 1FGL J1018.6-5856 at 20 epochs over 50 days using the CHIRON spectrograph, obtaining spectra at R~25,000 covering 4090-8908A. The average spectrum confirms an O6 V((f)) spectral type and extinction E(B-V) = 1.35+/-0.04. Variable absorption line equivalent widths suggest substantial contamination by wind line features. The limited S/N ratio hindered accurate continuum definition and prevented measurement of a high quality radial velocity curve. Nevertheless, the best data indicate a radial velocity amplitude <40 km/s for the He II lines and substantially lower for H I. We argue that this indicates a most likely compact object mass <2.2Msun. While black hole solutions are not excluded, a neutron star source of the gamma-ray emission seems preferred.Comment: 5 figures. To appear in the Astrophysical Journa