| Autor: |
Fürst, F., Walton, D. J., Israel, G. L., Bachetti, M., Barret, D., Brightman, M., Earnshaw, H. P., Fabian, A., Heida, M., Imbrogno, M., Middleton, M. J., Pinto, C., Salvaterra, R., Roberts, T. P., Castillo, G. A. Rodríguez, Webb, N. |
| Předmět: |
|
| Zdroj: |
Astronomy & Astrophysics / Astronomie et Astrophysique; 3/28/2023, Vol. 672, p1-10, 11p |
| Abstrakt: |
NGC5907 ULX1 is the most luminous ultra-luminous X-ray pulsar (ULXP) known to date, reaching luminosities in excess of 1041 erg s1. The pulsar is known for its fast spin-up during the on-state. Here, we present a long-term monitoring of the X-ray flux and the pulse period between 2003 and 2022. We find that the source was in an off- or low-state between mid-2017 to mid-2020. During this state, our pulse period monitoring shows that the source had spun down considerably. We interpret this spin-down as likely being due to the propeller effect, whereby accretion onto the neutron star surface is inhibited. Using state-of-the-art accretion and torque models, we use the spin-up and spin-down episodes to constrain the magnetic field. For the spin-up episode, we find solutions for magnetic field strengths of either around 1012 G or 1013 G, however, the strong spin-down during the off-state seems only to be consistent with a very high magnetic field, namely, >1013 G. This is the first time a strong spin-down is seen during a low flux state in a ULXP. Based on the assumption that the source entered the propeller regime, this gives us the best estimate so far for the magnetic field of NGC5907 ULX1. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
