CHANG-ES. III. UGC 10288—AN EDGE-ON GALAXY WITH A BACKGROUND DOUBLE-LOBED RADIO SOURCE

摘要

This third paper in the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES) series shows the first results from our regular data taken with the Karl G. Jansky Very Large Array. The edge-on galaxy, UGC?10288, has been observed in the B, C, and D configurations at L band (1.5?GHz) and in the C and D configurations at C band (6?GHz) in all polarization products. We show the first spatially resolved images of this galaxy in these bands, the first polarization images, and the first composed image at an intermediate frequency (4.1?GHz) which has been formed from a combination of all data sets. A surprising new result is the presence of a strong, polarized, double-lobed extragalactic radio source (CHANG-ES A) almost immediately behind the galaxy and perpendicular to its disk. The core of CHANG-ES A has an optical counterpart (SDSS J161423.28–001211.8) at a photometric redshift of z phot = 0.39; the southern radio lobe is behind the disk of UGC?10288 and the northern lobe is behind the halo region. This background "probe" has allowed us to do a preliminary Faraday rotation analysis of the foreground galaxy, putting limits on the regular magnetic field and electron density in the halo of UGC?10288 in regions in which there is no direct detection of a radio continuum halo. We have revised the flux densities of the two sources individually as well as the star formation rate (SFR) for UGC?10288. The SFR is low (0.4-0.5 M ☉ yr–1) and the galaxy has a high thermal fraction (44% at 6?GHz), as estimated using both the thermal and non-thermal SFR calibrations of Murphy et al. UGC?10288 would have fallen well below the CHANG-ES flux density cutoff, had it been considered without the brighter contribution of the background source. UGC?10288 shows discrete high-latitude radio continuum features, but it does not have a global radio continuum halo (exponential scale heights are typically ≈1?kpc averaged over regions with and without extensions). One prominent feature appears to form a large arc to the north of the galaxy on its east side, extending to 3.5?kpc above the plane. The total minimum magnetic field strength at a sample position in the arc is ~10 μG. Thus, this galaxy still appears to be able to form substantial high latitude, localized features in spite of its relatively low SFR.