TY - JOUR
T1 - An Optically Discovered Outburst from XTE J1859+226
AU - Bellm, Eric C.
AU - Wang, Yuankun
AU - van Roestel, Jan
AU - Phillipson, Rebecca A.
AU - Coughlin, Michael W.
AU - Tomsick, John A.
AU - Groom, Steven L.
AU - Healy, Brian
AU - Purdum, Josiah
AU - Rusholme, Ben
AU - Sollerman, Jesper
AU - Bealo, Peter
AU - Lora, Stefano
AU - Muyllaert, Eddy
AU - Peretto, Ivo
AU - Schwendeman, Erik J.
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - Using the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2 × 1035 erg s−1, implying an Eddington fraction of about 3 × 10−4. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 1011 cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.
AB - Using the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2 × 1035 erg s−1, implying an Eddington fraction of about 3 × 10−4. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 1011 cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.
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U2 - 10.3847/1538-4357/acf37c
DO - 10.3847/1538-4357/acf37c
M3 - Article
AN - SCOPUS:85175073085
SN - 0004-637X
VL - 956
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 21
ER -