Astronomy & Telescopes

The Visibility of the Ōtautahi-Oxford Interstellar Object Population Model in LSST

By Keith Cowing
Status Report
astro-ph.EP
February 25, 2025
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The Visibility of the Ōtautahi-Oxford Interstellar Object Population Model in LSST
2-dimensional illustrations for the on-sky locations (α, δ) for the first, discovery, and last images of the LSST discoveries with 13 ≤ H ≤ 14 for qs = 2.8 for all years (top row), odd rolling years (middle row) and even rolling years (bottom row). This excludes Year 2 of the simulation, which only deploys a rolling cadence over half of the survey footprint. The white star indicates the Solar Apex and the thin white line indicates the galactic plane. A sample of the observations for 10 ISOs is shown in the last column: the first, discovery, and last observations are connected by straight lines of random colour and the last observation is marked by a white dot to indicate the direction of motion. — astro-ph.EP

With a new probabilistic technique for sampling interstellar object (ISO) orbits with high efficiency, we assess the observability of ISOs under a realistic cadence for the upcoming Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST).

Using the Ōtautahi-Oxford population model, we show that there will be complex on-sky structure in the pattern of direction and velocity revealed by the detected ISO population, with the expected enhanced northern flux complicating efforts to derive population parameters from the LSST’s predominately southern footprint. For luminosity functions with slopes of 2.5≤qs≤4.0, the most discoverable ISOs have Hr≃14.6−20.7; for previously estimated spatial densities, between 6 and 51 total ISOs are expected.

The slope of the luminosity function of ISOs will be relatively quickly constrained. Discoveries are evenly split around their perihelion passage and are biased to lower velocities. After their discovery by LSST, it will be rare for ISOs to be visible for less than a month; most will have mr≤23 for months, and the window for spectroscopic characterization could be as long as two years.

These probabilistic assessments are robust against model or spatial density refinements that change the absolute numbers of ISO discoveries.

Rosemary C. Dorsey, Matthew J. Hopkins, Michele T. Bannister, Samantha M. Lawler, Chris Lintott, Alex H. Parker, John C. Forbes

Comments: Submitted to PSJ, comments welcome!
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2502.16741 [astro-ph.EP] (or arXiv:2502.16741v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2502.16741
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Submission history
From: Rosemary Dorsey
[v1] Sun, 23 Feb 2025 22:53:10 UTC (7,312 KB)
https://arxiv.org/abs/2502.16741
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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