Astrometric microlensing probes of the isolated neutron star population with Roman
<i>Context<i/>. Notoriously hard to detect and study, isolated neutron stars (NSs) might provide valuable answers to fundamental questions about stellar evolution and explosion physics. With the upcoming <i>Roman<i/> Space Telescope, scheduled for launch in 2026, a new and po...
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| Main Authors: | , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
March 2026
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| In: |
Astronomy and astrophysics
Year: 2026, Volume: 707, Pages: 1-12 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202558238 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202558238 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2026/03/aa58238-25/aa58238-25.html 
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| Author Notes: | Z. Kaczmarek, A. Halasi-Kun, P. McGill, S.E. Perkins, W.A. Dawson |
| Summary: | <i>Context<i/>. Notoriously hard to detect and study, isolated neutron stars (NSs) might provide valuable answers to fundamental questions about stellar evolution and explosion physics. With the upcoming <i>Roman<i/> Space Telescope, scheduled for launch in 2026, a new and powerful channel for their detection will become available: astrometric microlensing.<i>Aims<i/>. We set out to create a realistic sample of simulated gravitational microlensing events as observed by <i>Roman<i/> with the Galactic Bulge Time Domain Survey. We focus in particular on the population of NS lenses, which has until now been largely understudied.<i>Methods<i/>. We used dedicated Galactic models tailored for application to microlensing by compact objects. In addition to populations of stars, white dwarfs, and black holes, we simulated four different NS populations with Maxwellian natal kick distributions: = (150, 250, 350, 450) km/s. For each simulation, we applied projected <i>Roman<i/> precision, cadence, and detectability criteria.<i>Results<i/>. We found that the parameter space log<sub>10<sub/> <i>t<i/><sub>E<sub/>-log<sub>10<sub/> <i>θ<i/><sub>E<sub/>, which will be accessible to <i>Roman<i/> observations, is efficient for the classification of stellar remnants. We found a feature in this space that is characteristic of NSs; using this feature, optimal samples of NS candidates can be constructed from <i>Roman<i/>-like datasets. We describe the dependence of the observable parameter distributions on the assumed mean kick velocities. As the effects of natal kicks are very complex and mutually counteracting, we suggest that more detailed studies focused on the dynamics of NSs are needed in anticipation of <i>Roman<i/> and future surveys. We estimate that <i>Roman<i/> will observe approximately 11 000 microlensing events, including ~100 with NS lenses, whose photometric and astrometric signals are detectable; the event yield decreases by 38% when gap-filling low-cadence observations are not included. We make all simulated microlensing event datasets publicly available in preparation for <i>Roman<i/> data. |
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| Item Description: | Veröffentlicht: 8. April 2026 Gesehen am 09.06.2026 Online veröffentlicht: 8. April 2026 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202558238 |