Insight-HXMT detects hard X-ray pulsation from MAXI J1816-195
ATel #15471; Zhaosheng Li (Xiangtan University), L. Kuiper (SRON), M. Falanga (ISSI, UniBE), R. X. Xu (PKU), Y. Y. Pan (Xiangtan University), S. N. Zhang (IHEP), S. Zhang (IHEP), J. L. Qu (IHEP), L. M. Song (IHEP), Y. P. Chen (IHEP), L. Tao (IHEP), Y. Huang (IHEP), J. Poutanen (University of Turku)
on 25 Jun 2022; 07:27 UT
Credential Certification: Zhaosheng Li (lizhaosheng@xtu.edu.cn)
Subjects: X-ray, Binary, Pulsar
MAXI J1816-195 is a new X-ray transient, discovered by the Gas Slit Camera
(GSC) aboard Monitor of All Sky X-ray image (MAXI) during an outburst
on 7 June 2022 (MJD 59737; ATel #15418). Lately, NICER detected a thermonuclear X-ray burst and the coherent pulsations (ATel #15425), and measured the orbital parameters (ATel #15431), confirming that MAXI J1816-195 hosts an accreting millisecond X-ray pulsar with the spin frequency of 528 Hz. Following the trigger of MAXI, Insight-HXMT observed MAXI J1816-195 with the total exposure of 327 ks between 2022-06-08 UTC04:03:36 and 2022-06-11 UTC22:46:48. The data were barycenter corrected using the position RA=274.20671 and Dec=-19.63306 from the Swift observation (ATel #15426). Then, we folded the pulse profile after correcting for the binary orbital motion using the parameters from ATel #15431. We found that pulsations are very prominently present in the Insight-HXMT Medium-Energy (ME) and High-Energy (HE) X-ray telescopes data. For the HE, we detect a significant pulsed signal up to ~45 keV with the 35-45 keV signal strength of 12 sigma. For the 20-35 keV band the detection is at a 35.4 sigma level. For the ME, significant pulsations are detected in the 5-35 keV band, with the 10-20 keV signal being at a 34.8 sigma level.
Insight-HXMT will continue to observe MAXI J1816-195. The observations of this bursting X-ray pulsar with broadbands is crucial to reveal the nature of accreting millisecond X-ray pulsar.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.
