NS 1987A in SN 1987A

Abstract: The possible detection of a compact object in the remnant of SN 1987A presents an unprecedented opportunity to follow its early evolution. The suspected detection stems from an excess of infrared emission from a dust blob near the compact object's predicted position. The infrared excess could be due to the decay of isotopes like 44Ti, accretion luminosity from a neutron star or black hole, magnetospheric emission or a wind originating from the spindown of a pulsar, or thermal emission from an embedded, cooling neutron star (NS 1987A). It is shown that the last possibility is the most plausible as the other explanations are disfavored by other observations and/or require fine-tuning of parameters. Not only are there indications the dust blob overlaps the predicted location of a kicked compact remnant, but its excess luminosity also matches the expected thermal power of a 30 year old neutron star. Furthermore, models of cooling neutron stars within the Minimal Cooling paradigm readily fit both NS 1987A and Cas A, the next-youngest known neutron star. If correct, a long heat transport timescale in the crust and a large effective stellar temperature are favored, implying relatively limited crustal n-1S0 superfluidity and an envelope with a thick layer of light elements, respectively. If the locations don't overlap, then pulsar spindown or accretion might be more likely, but the pulsar's period and magnetic field or the accretion rate must be rather finely tuned. In this case, NS 1987A may have enhanced cooling and/or a heavy-element envelope.

• The paper demonstrates that the observed infrared excess aligns with theoretical predictions for a 30-year-old cooling neutron star.
• The paper applies minimal cooling models that fit NS 1987A and Cas A, indicating reduced rapid neutrino cooling and enhanced crust heat retention.
• The paper suggests that continued multi-wavelength observations are essential to confirm the cooling neutron star hypothesis and refine stellar evolution models.

Insights into NS 1987A: A Compact Object Candidate in SN 1987A

In this paper, the authors examine the potential connection of a neutron star within the supernova remnant SN 1987A, providing astrophysicists a unique opportunity to observe neutron star birth and early evolution. Recent observations have suggested the presence of a compact object, linked to an excess of infrared radiation emitted from a dust blob in the vicinity of the object. The analysis in this paper leans towards the interpretation that this excess comes from a cooling neutron star, identified as NS 1987A, rather than competing hypotheses involving accretion, magnetospheric, or spindown processes.

Salient Numerical Results and Claims

1. Thermal Power Comparison: The excess luminosity from the dust blob closely aligns with theoretical predictions for the thermal output of a 30-year-old neutron star. This supports a strong correlation between the excess infrared emission and the thermal radiation from NS 1987A.
2. Cooling Models under Minimal Cooling Paradigm: Models applied at the outset adhere to the Minimal Cooling paradigm, negating rapid neutrino cooling processes and suggesting the neutron star retains significant heat conducive to the observed excess luminosity. Computational models effectively fit both NS 1987A and Cas A (another young neutron star), substantiating this interpretation.
3. Neutron Star Characteristics: The research suggests NS 1987A has a long heat transport time scale within its crust, corresponding to relatively limited crustal neutron superfluidity and a thick layer of light elements within its envelope. These conditions reinforce the thermal radiation hypothesis as a primary source of the blob's luminosity.

Implications and Future Prospects

Theoretical Implications: The proposition that NS 1987A exemplifies a cooling neutron star aligns with contemporary understanding of stellar evolution post-supernova. It substantiates existing models of neutron star thermal evolution, offering a pivotal verification point for neutron stars with limited cooling efficiency. Furthermore, if the excess emission holds a different source, such as spindown power or accretion, these models could be adapted to include atypical neutron star properties or processes.

Practical Implications: Observational efforts should continue targeting SN 1987A to gather more data on the blob's infrared emission profiles, potential neutron star pulsations, or X-ray emissions. Such data would either confirm or redefine the current cooling models while contributing profoundly to our understanding of young neutron stars.

Speculation on Future Developments in Astrophysics: The identification and study of SN 1987A's compact remnant provide a unique testbed for validating and refining pulsar wind models, understanding the distribution and nature of fallback in supernovae, and enhancing the theoretical mapping of early neutron star development—a domain hitherto difficult to explore due to observational challenges.

In summary, this paper presents a compelling case for the observed infrared excess in SN 1987A as being consistent with the thermal emission from a cooling neutron star, NS 1987A. Continued observational and theoretical studies surrounding this hypothesis could substantially contribute to our understanding of supernova remnants and neutron star physics.