TY - JOUR
T1 - The Orbit of NGC 5907 ULX-1
AU - Belfiore, Andrea
AU - Salvaterra, Ruben
AU - Sidoli, Lara
AU - Israel, Gian Luca
AU - Stella, Luigi
AU - De Luca, Andrea
AU - Mereghetti, Sandro
AU - Esposito, Paolo
AU - Pintore, Fabio
AU - D’Aì, Antonino
AU - Rodrìguez Castillo, Guillermo
AU - Walton, Dominic J.
AU - Fürst, Felix
AU - Magistrali, Danilo
AU - Wolter, Anna
AU - Imbrogno, Matteo
N1 - © 2024. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/
PY - 2024/4/9
Y1 - 2024/4/9
N2 - We report on the orbit of the binary system powering the most extreme ultraluminous X-ray pulsar known to date: NGC 5907 ULX-1 (hereafter ULX1). ULX1 has been the target of a substantial multi-instrument campaign, mainly in the X-ray band, but no clear counterparts are known in other bands. Although ULX1 is highly variable and pulsations can be transient (regardless of the source flux), the timing data collected so far allow us to investigate the orbit of this system. We find an orbital period P orb = 5.7 − 0.6 + 0.1 days and a projected semi-axis A 1 = 3.1 − 0.9 + 0.8 lt - s . The most likely ephemeris is P
orb = 5.6585(6) days, A
1 = 3.1(4) lt-s, and the epoch of ascending nodes passage is T
asc = 57751.37(5) MJD. However, there are six similar solutions acceptable within 3σ. We find further indications that ULX1 is a high-mass X-ray binary. This implies that we are observing its orbit face on, with an inclination <5°.
AB - We report on the orbit of the binary system powering the most extreme ultraluminous X-ray pulsar known to date: NGC 5907 ULX-1 (hereafter ULX1). ULX1 has been the target of a substantial multi-instrument campaign, mainly in the X-ray band, but no clear counterparts are known in other bands. Although ULX1 is highly variable and pulsations can be transient (regardless of the source flux), the timing data collected so far allow us to investigate the orbit of this system. We find an orbital period P orb = 5.7 − 0.6 + 0.1 days and a projected semi-axis A 1 = 3.1 − 0.9 + 0.8 lt - s . The most likely ephemeris is P
orb = 5.6585(6) days, A
1 = 3.1(4) lt-s, and the epoch of ascending nodes passage is T
asc = 57751.37(5) MJD. However, there are six similar solutions acceptable within 3σ. We find further indications that ULX1 is a high-mass X-ray binary. This implies that we are observing its orbit face on, with an inclination <5°.
KW - High time resolution astrophysics
KW - Ultraluminous x-ray sources
KW - High mass x-ray binary stars
KW - Orbit determination
UR - http://www.scopus.com/inward/record.url?scp=85189979061&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ad320a
DO - 10.3847/1538-4357/ad320a
M3 - Article
SN - 0004-637X
VL - 965
SP - 1
EP - 8
JO - The Astrophysical Journal
JF - The Astrophysical Journal
IS - 1
M1 - 78
ER -