Detection of X-ray brightening from the X-ray pulsar XTE J1829-098

ATel #15551; Amar Deo Chandra (IISER Kolkata)
on 15 Aug 2022; 12:30 UT
Credential Certification: Amar Deo Chandra (amar.deo.chandra@gmail.com)

Tweet

The 7.8 s X-ray pulsar XTE J1829-098 (ATel #317) is currently undergoing an X-ray activity having daily averaged 2-20 keV flux from MAXI/GSC data of 0.078 +- 0.015 photons/s/cm^2 (21 +- 4 mCrab) on 2022-08-14 (MJD 59805). The latest daily averaged 15-50 keV flux from Swift/BAT monitoring observations of the source is 0.008 +- 0.002 count/cm^2/s (36 +- 11 mCrab) on 2022-08-14 (MJD 59805). Previous outbursts of the source have been detected in 2004 July-August (ATel #317), 2008 August (ATel #2007), 2009 August (ATel #11927), 2018 August (ATel #11927) and 2021 April (ATel #14521, #14554). The source was found to be active on 2003 March 27 using archival XMM-Newton Galactic Plane Survey observations (ATel #319). The source was also found to be active in 2019 December and 2020 August from MAXI/GSC archival observations (ATel #14554).

The time duration between successive outbursts was suggested to be ~246 days with outbursts lasting about 7 days (ATel #2007). Using a new ephemeris derived from the MAXI/GSC data spanning a duration of about 11 years (ATel #14554), the beginning of X-ray outbursts can be predicted using T_outburst = MJD 58341.73 + n * (243.66 +- 3.07), where n is the number of orbit since the outburst in 2018 August (ATel #14554). The onset of the current X-ray brightening of XTE J1829-098 around MJD 59794 nicely matches with the prediction of MJD 59803.69 +- 18.42. This suggests that the orbital period of the X-ray binary is indeed about 246 days as suggested earlier (ATel #2007, #14554).

There are known optical/NIR counterparts for the source (ATel #344; Halpern and Gotthelf, 2007, ApJ, 669, 579), but further IR/optical observations are required to ascertain the type and the class of the companion star.

The MAXI and Swift light curves of XTE J1829-098 are available at the URLs: http://maxi.riken.jp/star_data/J1829-098/J1829-098.html, https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1829-098/.

We deeply apologise for the glitch in the title of the previous ATel. Further multiwavelength observations of the source are encouraged.