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arXiv · 0906.5109

No Neutron Star Companion To The Lowest Mass SDSS White Dwarf

Marcel Agueros·Craig Heinke·Fernando Camilo·Mukremin Kilic·Scott Anderson·Paulo Freire·Scot Kleinman·James Liebert·Nicole Silvestri
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Abstract

SDSS J091709.55+463821.8 (hereafter J0917+4638) is the lowest surface gravity white dwarf (WD) currently known, with log g = 5.55 +/- 0.05 (M ~ 0.17 M_sun; Kilic et al. 2007a,b). Such low-mass white dwarfs (LMWDs) are believed to originate in binaries that evolve into WD/WD or WD/neutron star (NS) systems. An optical search for J0917+4638's companion showed that it must be a compact object with a mass >= 0.28 M_sun (Kilic 2007b). Here we report on Green Bank Telescope 820 MHz and XMM-Newton X-ray observations of J0917+4638 intended to uncover a potential NS companion to the LMWD. No convincing pulsar signal is detected in our radio data. Our X-ray observation also failed to detect X-ray emission from J0917+4638's companion, while we would have detected any of the millisecond radio pulsars in 47 Tuc. We conclude that the companion is almost certainly another WD.

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Marcel Agueros, Craig Heinke, Fernando Camilo, Mukremin Kilic, Scott Anderson, Paulo Freire, Scot Kleinman, James Liebert, Nicole Silvestri. 2009-06-29. No Neutron Star Companion To The Lowest Mass SDSS White Dwarf. https://doi.org/10.1088/0004-637x/700/2/l123

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