Identification of recent (few Myr) nearby (within 160 pc) supernovae from high-mass X-ray binaries in connection to the 60-Fe found in the Earth crust

• Applicant: Professor Dr. Ralph Neuhäuser
• Subject Area: Astrophysics and Astronomy
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 539758062

60-Fe was found in the Earth crust which arrived at Earth 1.5-3.2 Myr ago and originated from 8-16 nearby (within 160 pc) core-collapse supernovae (SNe). By tracing back the neutron stars formed in those SNe, one can determine the location and time of such SNe. So far, three such neutron stars were suggested: (i) RXJ1856 now at 123 pc was probably born 0.5 Myr ago in Upper Sco; (ii) runaway star zeta Oph and radio pulsar PSR1706 were probably both ejected in a SN 1.8 Myr ago at 107 pc in Upper Centaurus Crux - but due to beaming limitations, it is unlikely to find many more of those 8-16 neutron stars as pulsars, (iii) additionally, the high-mass X-ray binary (HMXB) 1H11255-567 in Lower Centaurus Crux could also contain a (young nearby) neutron star. The SNe, in which those neutron stars were born, produced some of the 60-Fe found in the Earth. Several more such young nearby HMXBs can be found, which formed in the remaining of those 8-16 SNe, because a significant fraction of multiples remains bound after the SN. Because of the bright optical high-mass star in such HMXBs (OB-type star plus compact object), there is no beaming limitation (compared to pulsars). In this project, we will search for such HMXBs among OB stars within 160 pc by their X-ray emission (unusual X-ray to optical flux ratio, non-thermal spectra, pulsation) in order to find evidence for more recent nearby SNe that provided the 60-Fe found on Earth. The results may also constrain SN nucleosynthesis yield models.

• DFG Programme: Research Grants
• International Connection: Austria
• Cooperation Partner: Professor Dr. Norbert Przybilla