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Blast: the far-infrared/radio correlation in distant galaxies
David Hughes
Acceso Abierto
Galaxies: evolution
Infrared: galaxies
Radio continuum: galaxies
We investigate the correlation between far-infrared (FIR) and radio luminosities in distant galaxies, a lynchpin of modern astronomy. We use data from the Balloon-borne Large Aperture Submillimetre Telescope (BLAST), Spitzer, the Large Apex BOlometer CamerA (LABOCA), the Very Large Array (VLA) and the Giant Metre-wave Radio Telescope (GMRT) in the Extended Chandra Deep Field South (ECDFS). For a catalogue of BLAST 250-μm-selected galaxies, we re-measure the 70–870-μm flux densities at the positions of their most likely 24-μm counterparts, which have a median [interquartile] redshift of 0.74 [0.25, 1.57]. From these, we determine the monochromatic flux density ratio, q₂₅₀ (= log₁₀ [S₂₅₀μm/S₁‚₄₀₀MHz]), and the bolometric equivalent, q🇮🇷. At z ≈ 0.6, where our 250-μm filter probes rest-frame 160-μm emission, we find no evolution relative to q₁₆₀ for local galaxies. We also stack the FIR and submm images at the positions of 24-μm- and radio-selected galaxies. The difference between q🇮🇷 seen for 250-μm- and radio-selected galaxies suggests star formation provides most of the IR luminosity in ≲100-μJy radio galaxies, but rather less for those in the mJy regime. For the 24-μm sample, the radio spectral index is constant across 0 < z < 3, but q🇮🇷 exhibits tentative evidence of a steady decline such that q🇮🇷 ∝ (1 + z)⁻⁰͘¹⁵⁺⁻⁰͘⁰³ – significant evolution, spanning the epoch of galaxy formation, with major implications for techniques that rely on the FIR/radio correlation. We compare with model predictions and speculate that we may be seeing the increase in radio activity that gives rise to the radio background.
Monthly Notices of the Royal Astronomical Society
Público en general
Ivison, R. J., et al., (2010), Blast: the far-infrared/radio correlation in distant galaxies, Monthly Notices of the Royal Astronomical Society, Vol. 402(1): 245-258
Versión aceptada
acceptedVersion - Versión aceptada
Appears in Collections:Artículos de Astrofísica

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