We have discovered a previously unnoticed X-ray source 3.2 ^{\circ} away fromthe Galactic Center. Its XMM/MOS light curve has a periodic variability at614.28s( \approx 3.8 \sigma ). Its X-ray spectrum is perfectly described by anabsorbed 1.8keV blackbody plus Fe-line features. It has an L_{\mathrm{X}} about 1.2\times10^{34}\times (D/10 kpc) ^{2} erg s ^{-1} and has no obviousoptical counterpart(fx/fo > 1600). We argue it is most likely a neutron-starultra-compact X-ray binary with the shortest orbital period so far. We proposean XMM/PN observation to constrain its nature by\: 1) verifying the 614s signaland looking for a possible rotational period, 2)checking its new spectral shapeand whether other spectral components exist with more X-ray photons.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2021-03-02T21:31:10Z/2021-03-03T14:59:30Z
Version
18.02_20200221_1200
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Dr Hang Gong, 2022, 'Verifying A Neutron-Star UCXB Candidate with A Possibly 10.2-min Orbital Period', 18.02_20200221_1200, European Space Agency, https://doi.org/10.57780/esa-9f3nfdc
