In the event you have been fortunate sufficient to look at a complete eclipse, you’re sure to recollect the halo of sensible gentle across the Moon throughout totality. It’s generally known as the corona, and it’s the diffuse outer environment of the Solar. Though it’s so skinny we’d take into account it a vacuum on Earth, it has a temperature of thousands and thousands of levels, which is why it’s seen throughout a complete eclipse. In keeping with our understanding of black gap dynamics black holes must also have a corona. And just like the Solar’s corona, it’s normally troublesome to look at. Now a research in The Astrophysical Journal has made observations of this elusive area.
For an energetic black gap, it’s usually thought that there’s a donut-shaped torus of fuel and dirt surrounding the black gap, in which there’s an accretion disk of heated materials aligned alongside the rotational aircraft of the black gap. Streaming from the polar areas of the black gap are jets of ionized fuel rushing away at almost the pace of sunshine. This mannequin would clarify the assorted forms of energetic galactic nuclei (AGNs) we observe, because the orientation of the black gap relative to us modifications the looks of the AGN.
In keeping with the mannequin, the innermost area of the accretion disk ought to be a superheated area at close to vacuum density, which streams into the black gap. It’s a corona just like the Solar’s, however as an alternative of thousands and thousands of levels, it has a temperature of billions of levels. However as a result of it’s so diffuse, its gentle is overwhelmed by the sunshine of the accretion disk.
On this new research, the group used a trick much like observing the Solar’s corona throughout a complete eclipse. The orientation of a black gap relative to us signifies that for some black holes the torus of fuel and dirt obscures our view of the accretion disk area, whereas for different black holes we will see the disk straight. These are generally known as obscured and unobscured black holes. The obscured black holes are much like an eclipsed Solar, because the gentle of the accretion disk is blocked from view. Sadly, so is the black gap’s corona. However the corona is so sizzling that it emits extraordinarily high-energy X-rays. These X-rays can scatter off materials within the torus and mirror into our line of website.
Utilizing knowledge from NASA’s Imaging X-ray Polarimetry Explorer (IPXE), the group gathered knowledge on a dozen obscured black holes, together with Cygnus X-1 and X-3 within the Milky Means, and LMG X-1 and X-3 within the Massive Magellanic Cloud. They weren’t solely capable of observe scattered X-rays from the coronas of those black holes, they have been additionally capable of detect a sample amongst them. Primarily based on the information, the corona surrounds the black gap in a disk much like the accretion disk, fairly than surrounding the black gap in a sphere much like the Solar’s corona.
Analysis corresponding to it will assist astronomers refine our fashions of black holes. It can additionally assist us higher perceive how black holes eat matter and energy the AGNs we observe in distant galaxies.
Reference: Saade, M. Lynne, et al. “A Comparability of the X-Ray Polarimetric Properties of Stellar and Supermassive Black Holes.” The Astrophysical Journal 974.1 (2024): 101.
