G515, Revististed. I. Stellar Populations and Evidence of Nuclear Activity in a Luminous E+A Galaxy

C. Liu, E. Hooper, K. O'Neil, D. Thompson, M. Wolf

2006 ApJ accepted


We present multiwavelength observations of the very luminous "E+A" galaxy known as G515 (J152426.55+080906.7), including deep Ks imaging, spatially re- solved Halpha spectroscopy, and radio observations. The data, together with detailed spectral synthesis of the galaxy.s integrated stellar population, show that G515 is a ~1 Gyr old post-merger, post-starburst galaxy. We detect no Balmer line emission in the galaxy, although there is a small amount of [N II] lambda 6548, 6583 angstrom emission. The galaxy's HI mass has a 2sigma upper limit of 1.0 109 Msol. IRAS detections in the 60microm and 100microm bands indicate a far infrared luminos- ity of ~5.8 1010 Lsol. A small amount (~3 mJy) of radio continuum flux, which appears to be variable, has been detected. The data suggest that G515 may have once been an ultraluminous infrared galaxy, and may harbor a weak, dust-obscured active nucleus.

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