When a supermassive black gap consumes a star, it doesn’t simply swallow it entire. It shreds the star, ripping it aside little by little earlier than consuming the stays. It’s a messy course of often known as a tidal disruption occasion (TDE). Astronomers often catch a glimpse of TDEs, and one current one has helped resolve a thriller a couple of sort of transient X-ray supply.
Often called quasi-periodic eruptions (QPEs), they’re delicate X-rays that emanate from the facilities of galaxies each few hours or a number of weeks. QPEs are uncommon, so they’re troublesome to review, and we aren’t certain what causes them. One thought is that they’re attributable to a big star or stellar black gap orbiting the supermassive black gap in such a approach that its orbit intersects with the accretion disk of the supermassive black gap. Every time the smaller object passes by the disk, it triggers superheated plasma to launch X-rays. We’ve seen a related impact with blazars, for instance.
Given the quick periodicity of QPEs the companion object would wish to orbit the black gap very carefully, simply on the sting of a steady orbit distance. And when it begins intersecting with accretion disk materials, its orbit will decay on a brief cosmic timescale. This is able to clarify why QPEs are so uncommon. However to show this mannequin, astronomers would wish to watch this taking place in actual time, which is what a staff of astronomers has just lately achieved. The outcomes will probably be revealed in Nature later this month.
The story begins with an remark by the Zwicky Transient Facility again in 2019. The ZTF captured an optical flare that had all of the markings of a tidal disruption occasion. It got here to be often known as TDE AT2019qiz. In line with black gap fashions, when a star is ripped aside, a lot of the fabric kinds an accretion disk across the black gap inside a number of years. This is able to make for good QPE circumstances if there was a detailed companion object. So the staff aimed the Chandra X-ray Observatory at AT2019qiz often, hoping to seize a quasi-periodic eruption. Certain sufficient, in 2023, the staff began to watch X-ray flashes erupting about each 48 hours. Observations from the Swift and AstroSAT telescopes additional confirmed the consequence.
It isn’t identified whether or not the companion is a star or small black gap, and the staff wish to seize extra QPEs occurring after identified tidal disruption occasions, however this preliminary result’s fairly clear.
Reference: Nicholl, M., et al. “Quasi-periodic X-ray eruptions years after a close-by tidal disruption occasion.” arXiv preprint arXiv:2409.02181 (2024).
