Half of Astronomy Papers Use AI
Researchers scanned the full text of 207,111 astro-ph papers from 2015 to mid-2026, tracking vocabulary characteristic of language-model assistance. Using a hierarchical Bayesian model calibrated on pre-2020 papers (unassisted) and 392 papers that explicitly disclosed AI use, they estimated the assisted share of writing across years.
Depending on assumptions, the 2025 estimate ranges from 36% to over 54% of papers, staying above half in most scenarios. Yet only 0.81% of 2025 papers formally disclose model use, meaning roughly one declaration for every 66 papers bearing a trace. The signal is also fading: the telltale word excess more than halved between 2023 and 2026, as authors adapt their prose to avoid detection.
Dawn-Era Quasars at Eddington Limit
Astronomers examined the spectra of 21 quasars at redshifts 6.07–6.90 with JWST/NIRSpec and Subaru/MOIRCS, expanding the sample with earlier data to 27 quasars total. Measured black hole masses range from about 16 million to 2.5 billion solar masses, with accretion rates ranging from well below to above the Eddington limit.
Compared to similarly luminous quasars at z~1.3, early-universe black holes tend to be less massive but accrete more vigorously. 11% of the high-redshift sample grows at or near the Eddington limit, rising to 22% under an alternative calibration. The result supports an anti-hierarchical growth scenario, where the most massive black holes form fastest.
JWST Hunts Primordial Black Holes in M31
The team built FLASH, a data pipeline capable of detecting minute-scale microlensing flashes of stars in JWST/NIRCam images. Such brief brightenings would occur if dark matter consists of primordial black holes lighter than 10⁻¹⁰ solar masses — objects too fast-fading for ground-based surveys to catch.
Applying the method to images of the M31 disk taken at 21.5-second cadence, the researchers found no such events, setting the first JWST-based constraint on primordial black holes of about 10⁻⁹ solar masses as dark matter. Although the observations weren't optimized for microlensing, the result shows JWST can competitively monitor crowded fields, and a dedicated program could substantially tighten limits on compact dark matter.
Youngest Companion to a Millisecond Pulsar
Astronomers identified the optical counterpart of millisecond pulsar NGC362D in the globular cluster NGC362 using deep, multi-band Hubble observations. The object turned out to be a very low-mass (about 0.18 solar masses) helium white dwarf still in its pre-cooling phase, having finished the mass-transfer process only about 0.6 billion years ago — making it the youngest known companion of its kind.
Notably, its photometric properties show wavelength-dependent variations never before seen in such systems, pointing to leftover circumstellar material. This offers a rare direct look at the immediate aftermath of pulsar recycling, and shows that residual material can mimic signatures of non-degenerate companions, complicating the classification of young millisecond pulsars.
Most Distant Galaxy Protocluster Found
Using data from the ODIN survey, captured with the DECam instrument on the 4-meter Blanco Telescope in Chile, an international team led by Vandana Ramakrishnan identified 150 distant protoclusters that formed when the universe was 1–3 billion years old. Among them, two structures, COSMOS-z3.1-A and COSMOS-z3.1-C, stood out for their extreme galaxy overdensity.
To reconstruct the 3D distribution of galaxies, researchers used the DESI spectrograph, capable of measuring distances to 5,000 galaxies simultaneously. The result confirms the most distant known ancestor of a galaxy supercluster, with a mass of about 5,000 Milky Ways, sitting in one of the densest regions of the cosmic web ever observed. The discovery supports existing theories of cluster evolution and reveals how these structures connect to the wider cosmic web.
