Astronomers from Ohio American University and collaborators around the world have conducted a detailed set of X-ray observations focused on an unusual nuclear transition feature marked by the name AT2019pev. Their findings, which shed new light on the nature of this peculiar object, have been shared as a preprint on arXiv.org and have since been accepted for publication in a major astronomy journal.
AT2019pev, also known as ZTF19abvgxrq and Gaia19eby, represents a dramatic and clearly evolving astronomical source. It was first detected on September 1, 2019, and is characterized as a type I Seyfert galaxy, meaning its center hosts an active supermassive black hole. The object exhibits narrow spectral lines at a redshift of 0.096, and initial interpretations suggested two competing scenarios: a tidal disruption event where a star is torn apart by the black hole, or alternative processes linked to activity in the galaxy’s core.
A research team led by You Zhefu of Ohio State University revisited the X-ray data to determine which explanation best fits the observations. The team integrated measurements from multiple space observatories, including NASA’s Swift and Chandra missions as well as the NICER telescope aboard the International Space Station. These combined data revealed a notable increase in X-ray luminosity by about a factor of five, occurring roughly five days after the first Swift observation during what researchers describe as the Swift XRT era. The following weeks and months showed continued variability, with fluctuations spanning tens of days. Moreover, the X-ray spectra indicated a trend toward a harder X-ray component as the event progressed, signaling changes in the inner accretion disk and the behavior of material drawn toward the black hole. In parallel, optical data from the ESA Gaia mission helped constrain the timing of the optical brightening, showing that the visible light reached maximum intensity roughly 223 days after the initial detection. These multiwavelength measurements together map a dynamic picture of the region where matter is heated as it spirals inward toward the black hole’s event horizon.
By bringing together observations across X-ray and optical regimes, the researchers conclude that the observed variability most likely arises from processes linked to activity in the active galactic nucleus itself rather than from a tidal disruption flare. The evidence points to shifts in accretion flow and disk state as the driving mechanisms behind the observed emissions, underscoring the complex interplay of gas dynamics, gravitational forces, and radiation in the immediate vicinity of a supermassive black hole. The work emphasizes how careful cross‑checking among different instruments and wavelengths can separate core activity from explosive transient events in galactic centers. For transparency, the data and interpretations are cross-referenced with the published preprint on arXiv and the forthcoming journal article, with attribution to the collaborating teams and institutions involved in this global effort.