ESA’s XMM-Newton has X-rayed this beautiful cosmic creature, known as the Manatee Nebula, pinning down the location of unusual particle acceleration in its ‘head’.

The Manatee Nebula, or W50, is thought to be a large supernova remnant created when a giant star exploded around 30 000 years ago, flinging its shells of gases out across the sky. It is one of the largest such features known, spanning the equivalent size of four full Moons.

Unusually for a supernova remnant, a black hole remains in its core. This central ‘microquasar’, known as SS 433, emits powerful jets of particles travelling at speeds close to a quarter the speed of light that punch through the gassy shells, creating the double-lobed shape.

SS 433 is identified by the red dot in the middle of the image. The X-ray data acquired by XMM-Newton are represented in yellow (soft X-rays), magenta (medium energy X-rays) and cyan (hard X-ray emission), while red is radio and green optical wavelengths imaged by the Very Large Array and the Skinakas Observatory in Greece, respectively. NASA NuSTAR and Chandra data were also used for the study (not shown in this image).

The nebula attracted attention in 2018 when the High-Altitude Water Cherenkov Observatory, which is sensitive to very high energy gamma-ray photons, revealed the presence of highly energetic particles (hundreds of tera electron volts), but could not pinpoint from where within the Manatee the particles were originating.

XMM-Newton was crucial in homing in on the region of particle acceleration in the X-ray jet blasting from the Manatee’s head, which begins about 100 light years away from the microquasar (represented by the magneta and cyan colours towards the left side SS 433) and extends to approximately 300 light years (coinciding with the radio ‘ear’ where the shock terminates).

Samar Safi-Harb of the University of Manitoba, Canada, who led the study, says “thanks to the new XMM-Newton data, supplemented with NuSTAR and Chandra data, we believe the particles are getting accelerated to very high energies in the head of the Manatee through an unusually energetic particle acceleration process. The black hole outflow likely made its way there and has been re-energized to high-energy radiation at that location, perhaps due to shock waves in the expanding gas clouds and enhanced magnetic fields.”

The nebula acts as a nearby laboratory for exploring a wide range of astrophysical phenomena associated with the outflows of many galactic and extragalactic sources and will be subject to further investigation. Furthermore, follow-up studies by ESA’s future Athena X-ray observatory will provide even more sensitive details about the inner workings of this curious cosmic Manatee.

The paper Hard X-ray emission from the eastern jet of SS 433 powering the W50 ‘Manatee’ nebula: Evidence for particle re-acceleration has been accepted for publication in the Astrophysical Journal, and is also available via arXiv.