The Extragalactic Population of Accreting Neutron Stars and the Ultraluminous X-ray Sources Paradigm: from ULTraS to PULSULTraS
Abstract
The unambiguous identification of the nature of a neutron star in X-rays is achieved through the detection of coherent signals reflecting the spin period of the compact object. The search for coherent signals in the whole XMM-Newton source catalog was one of the main aims of the EU/FP7-funded project EXTraS (active in 2014-2016). The ULTraS and PULSULTraS projects start from the findings achieved by EXTraS and concerning the X-ray pulsars identified in the Andromeda Galaxy and among the class of Ultraluminous X-ray Sources (ULXs). In particular, we focused on the development of data analysis tools able to account for the extreme timing properties of pulsars moving in binary orbits and accreting at super-Eddington rates, i.e with very high first period derivative values, that made their discovery elusive. Part of these tools are becoming available to the whole community through their inclusion in the Stingray software package. Then, we searched for new extragalactic pulsars by applying the new developed timing tools to both archival data and a dedicated XMM-Newton Large Program: we discovered a new pulsating ULX in M51, the first pulsar in a low mass binary in M31, and twelve further pulsators of different nature (neutron stars and white dwarfs). At the same time we studied in great details the timing properties of the already known pulsating ULXs (M82 X-2, NGC7793 P13 and NGC5907 ULX-1).
- Publication:
-
Memorie della Societa Astronomica Italiana
- Pub Date:
- November 2022
- DOI:
- 10.36116/MEMSAIT_93N2_3.2022.4
- Bibcode:
- 2022MmSAI..93b..34I
- Keywords:
-
- Pulsars: general;
- Stars: neutron;
- Accretion;
- accretion disks;
- Catalogs;
- X-rays: binaries;
- X-rays: galaxies;
- Methods: data analysis