TOWARD IDENTIFYING 4U~1700-377 AS NEUTRON STAR OR BLACK HOLE
We aim to study 4U 1700-377, a high-mass X-ray binary system, to better understand how matter behaves around its bright companion star and address the ``mass-gap'' mystery. Depending on its true nature, 4U 1700-377 could either be the heaviest neutron star without detected pulsations or the smallest black hole ever found. Using XRISM's detailed spectral analysis, we plan to measure the central energies and the profiles of the neutral and ionized iron lines with unprecedented accuracy.
TELESCOP= 'XRISM ' / Mission name INSTRUME= 'XTEND ' / Instrument name OBS_ID = '201064010' / Observation identification string OBJECT = '4U1700-37' / Object name OBSERVER= 'SHINYA YAMADA' / PI name OBS_MODE= 'POINTING' / POINTING or SLEW or ALL RA_OBJ = 255.9865 / [deg] Object Right ascension DEC_OBJ = -37.8441 / [deg] Object Declination RA_PNT = 255.985114581194 / Pointing RA DEC_PNT = -37.8456662412695 / Pointing DEC RA_NOM = 255.987135717979 / [deg] Nominal aspect point R.A. DEC_NOM = -37.8436520403796 / [deg] Nominal aspect point Dec. PA_NOM = 88.5869835772094 / [deg] Nominal aspect point roll. TELAPSE = 117359.963101 / Elapsed time DATE-OBS= '2025-02-10T12:55:52.036829' / Start date DATE-END= '2025-02-11T21:31:51.999930' / Stop date ONTIME = 49984.416256 / On-source time EXPOSURE= 49984.416256 / Exposure time PROCVER = '03.00.013.010' / Processing script version MKFFF = 'ISAS/JAXA' / Origin of First FITS file ORIGIN = 'GSFC/NASA' / Origin of Processed FITS file SOFTVER = 'Hea_21Aug2024_V6.34_XRISM_21Aug2024_V001' / Version of HEADAS used CALDBVER= 'gen20241115_xtd20241115_rsl20241115' / Version of CALDB used DATE = '2025-02-18T06:06:18' / Date and time this file was created or updated SIB2_VER= 'V03.01 ' / SIB2 version JAXA