arXiv subjects

Renee Key

Publications and source records attributed to Renee Key.

3 recordsLinked to original sources

arXiv2026

AMPM I. A Targeted Search for Asteroid Mass Primordial Black Hole Microlenses

Gravitational microlensing is a powerful technique for constraining the abundance of dark matter in asteroid mass to supermassive primordial black holes at masses of $-11 \lesssim \log M/\mathrm{M}_\odot \lesssim 5$. In this work, we introduce a new high-cadence stellar microlensing survey in the Large Magellanic Cloud, AMPM. The primary goal of AMPM is to place constraints in the asteroid-to-planetary-mass regime of primordial black hole dark matter. We present the five nights of survey data, the microlensing detection pipeline, and the microlensing efficiency of AMPM. We explore the impact of the stellar distribution in the Large Magellanic Cloud on the microlensing detection efficiency and conduct a detailed analysis of second-order microlensing effects and the impact on the primordial black hole dark matter constraints. Our findings indicate that these second-order effects shift the maximum sensitivity of AMPM toward the lunar-mass black hole regime at $10^{-8} - 10^{-6} \, M_{\odot}$. From the five nights of data, we detect a single microlensing candidate and find that AMPM can constrain at the 95\% C.L up to 30\% of the Galactic primordial black hole dark matter distribution.

astro-ph.GA↗

arXiv2026

AMPM II. A Lunar-Mass Primordial Black Hole Microlensing Candidate in the Milky Way Halo

Primordial Black Holes (PBH) are hypothesised to form during inflation and have long been considered a candidate for compact dark matter. Gravitational microlensing is known as a productive method for exoplanet discovery and characterisation, but also provides an experimental avenue to constrain the PBH abundance in the mass regime from $\sim 10^{-11}\ M_{\odot}$ to $\sim 10^5\ M_{\odot}$. We performed a high-cadence, optical microlensing survey with DECam over five nights towards the Large Magellanic Cloud, sensitive to microlensing timescales from minutes to days. Here, we report the discovery of an hour-long microlensing event. An optical depth probabilistic analysis indicates that the lensing object, which we refer to as Phoebe, is 5 orders of magnitude more likely to be part of the Milky Way's dark matter halo than part of the stellar content of the Milky Way and Large Magellanic Cloud. No matter the location of Phoebe, it is among the fastest and lowest mass microlensing signals ever detected, with an Einstein timescale of approximately 60 minutes. Using Bayesian modelling, we interpret Phoebe as a PBH with mass $0.032^{+0.227}_{-0.027} M_{\oplus}$, or approximately 3 lunar masses. Phoebe suggests a population of compact, lunar-mass objects associated with the dark matter distribution of the Milky Way, and potentially opens a new window to the physics of inflation.

astro-ph.CO↗

arXiv2025

Cryoscope: A Cryogenic Infrared Survey Telescope in Antarctica

We present Cryoscope--a new 50 deg$^2$ field-of-view, 1.2 m aperture, $K_{dark}$ survey telescope to be located at Dome C, Antarctica. Cryoscope has an innovative optical-thermal design wherein the entire telescope is cryogenically cooled. Cryoscope also explores new detector technology to cost-effectively tile the full focal plane. Leveraging the dark Antarctic sky and minimizing telescope thermal emission, Cryoscope achieves unprecedented deep, wide, fast and red observations, matching and exceeding volumetric survey speeds from the Ultraviolet Explorer, Vera Rubin Observatory, Nancy Grace Roman Space Telescope, SPHEREx, and NEO Surveyor. By providing coverage beyond wavelengths of 2 $\mu$m, we aim to create the most comprehensive dynamic movie of the most obscured reaches of the Universe. Cryoscope will be a dedicated discovery engine for electromagnetic emission from coalescing compact binaries, Earth-like exoplanets orbiting cold stars, and multiple facets of time-domain, stellar and solar system science. In this paper, we describe the scientific drivers and technical innovations for this new discovery engine operating in the $K_{dark}$ passband, why we choose to deploy it in Antarctica, and the status of a fifth-scale prototype designed as a Pathfinder to retire technological risks prior to full-scale implementation. We plan to deploy the Cryoscope Pathfinder to Dome C in December 2026 and the full-scale telescope by 2030.

astro-ph.IM↗