Time-Traveling Signals: Astronomers Detect Echo from our Galaxy’s Black Hole Dating Back 200 Years

An International Team of Scientists Discovers Dormant Awakening of Milky Way’s Supermassive Black Hole 200 Years Ago.

A new study published today in Nature reveals that Sagittarius A* (Sgr A*), the supermassive black hole residing at the center of the Milky Way, experienced a significant reawakening two centuries ago.

Led by Frédéric Marin, a CNRS researcher at the Astronomical Strasbourg Observatory, the team unraveled the mysterious past activity of this colossal celestial entity, boasting a mass four million times that of the Sun.

During the early 19th century, over the course of a year, Sgr A* devoured nearby cosmic objects that ventured too close, before returning to a dormant state. Despite its immense power, Earth remained unaffected due to the vast distance, approximately two billion times the Earth-Sun separation.

However, the detection of an X-ray echo emitted around 200 years ago revealed that the initial intensity surpassed the current emission of Sgr A* by at least a millionfold. To put it in perspective, it’s akin to a single glow-worm hidden within a forest suddenly radiating brightness equal to that of the Sun.

These findings shed light on the amplified luminosity of galactic molecular clouds surrounding Sgr A*—they are currently shining more brightly due to the reflection of X-rays emitted by the black hole two centuries ago.

The team utilized NASA’s IXPE (Imaging X-ray Polarimetry Explorer) satellite, which, for the first time, precisely detected and identified the polarized X-ray light, previously deemed impossible. Acting like a compass, the polarized X-ray light directly points to its origin, Sgr A*, despite its current state of near-extinction.

Scientists are persistently studying Sgr A* to unravel the underlying physical mechanisms responsible for its transition from a dormant to an active state.

Source: 10.48550/arXiv.2304.06967 

Image Credit: © NASA/CXC/SAO/IXPE