The youngest white dwarf companion to a millisecond pulsar: Insights from NGC 362D

@misc{ettorre2026youngest,
  title = {{The youngest white dwarf companion to a millisecond pulsar: Insights from NGC 362D}},
  author = {Greta Ettorre and Emanuele Dalessandro and Mario Cadelano and Alessandro Ridolfi and Cristina Pallanca and Paulo C. C. Freire and Vivek Venkatraman Krishnan and Maurizio Salaris and Franca D'Antona and Rouhin Nag},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.05608},
  eprint = {2609.05608},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.05608},
}

TY  - UNPB
TI  - The youngest white dwarf companion to a millisecond pulsar: Insights from NGC 362D
AU  - Greta Ettorre
AU  - Emanuele Dalessandro
AU  - Mario Cadelano
AU  - Alessandro Ridolfi
AU  - Cristina Pallanca
AU  - Paulo C. C. Freire
AU  - Vivek Venkatraman Krishnan
AU  - Maurizio Salaris
AU  - Franca D'Antona
AU  - Rouhin Nag
PY  - 2026
DA  - 2026/09/04
PB  - arXiv
DO  - 10.48550/arxiv.2609.05608
UR  - https://arxiv.org/abs/2609.05608
AB  - We report on the identification of the optical counterpart to the recently discovered millisecond pulsar (MSP) NGC362D in the Galactic globular cluster NGC362 based on deep, multi-band, and multi-epoch Hubble Space Telescope observations. Our analysis robustly shows that this object is a very low-mass (∼0.18 M_⊙) He white dwarf (WD) still in the pre-cooling phase. Interestingly, a detailed comparison with updated binary evolution models indicates that this object completed the mass-transfer phase only recently (∼0.6 Gyr ago), thus strongly suggesting that COM-NGC362D is the youngest WD companion to a MSP identified to date. Remarkably, in this respect, the photometric properties of NGC362D show, for the first time in this class of objects, significant wavelength-dependent variations that are consistent with the presence of residual circumstellar material. This system therefore provides a valuable test case to directly probe the immediate aftermath of the MSP recycling process and to constrain the early evolutionary stages of proto-WD companions and their radio and optical properties. Our results suggest that residual material can produce radio and optical signatures that mimic those of systems with non-degenerate companions, potentially leading to the misclassification of young MSPs.
ER  -