Category: Black Holes

Astronomers Find Local Black Hole Jets

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Astronomers have confirmed the first known microblazar in the Milky Way: a stellar-mass black hole whose relativistic jet happens to be pointed almost directly at Earth. The system, catalogued as IRAS 18293-0941 and lying only about 12,000 light-years away, consists of a black hole and a companion star that completes an orbit every 11.38 days. Material stripped from the star forms an accretion disk that powers two jets racing outward at three-quarters the speed of light. One of those jets is aimed toward us; the opposite jet only becomes visible because it slams into a nearby molecular cloud, carving a bubble and heating gas until it glows.

The object had been sitting in infrared catalogues for decades, hidden behind thick dust that rendered it invisible in ordinary optical images. High-resolution radio observations with the European VLBI Network, combined with the precise stellar position from Gaia, finally pinned the jet to the binary itself rather than to some distant background galaxy. Where the receding jet strikes the cloud, particles appear to be accelerated to energies that may reach the petaelectronvolt range, making this modest stellar system one of the galaxy’s more efficient natural particle accelerators.

The discovery fulfills a theoretical prediction that has been on the books for thirty years. Researchers now plan to watch the jet evolve and to hunt for additional microblazars, which could turn out to play a quiet but important role in how galaxies process energy and cosmic rays. Rest easy, though: at this distance the beam poses no threat to Earth. It is simply a beautifully aligned laboratory sitting in our own backyard.

Read More: https://earthsky.org/space/black-hole-jet-aimed-at-us-galaxy-microblazar/

Scientists Measure Black Hole Formations

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JWST observations of galaxies less than a billion years after the Big Bang revealed unexpectedly massive black-hole “seeds,” which is hard to explain if those objects had to grow from ordinary stellar-mass remnants. That tension has revived the direct-collapse black hole (DCBH) picture: a massive, metal-poor gas cloud in the center of an early galaxy collapses in one shot into a heavy seed rather than assembling through a long chain of mergers.

An international team led by Alessandro Trinca used dark-matter merger trees from high-resolution N-body simulations, then fed those histories into the Cosmic Archaeology Tool to track which halos could actually form DCBHs. The models show that the most favorable sites are cosmic over-densities—regions already packed with gas, dust, and merging dark-matter clumps. Direct collapse can begin as early as about 500 million years after the Big Bang and continues until metal enrichment from the first supernovae shuts the channel down a few hundred million years later.

Those results give observers a concrete target: the descendants of DCBHs should turn up as companion AGN near bright quasars at redshift ~7. Finding a large population of such neighbors in future JWST surveys would be strong evidence that the first supermassive black holes grew in clustered, over-dense environments rather than in isolation.

Read More: https://www.universetoday.com/articles/researchers-measure-the-environment-where-the-first-supermassive-black-holes-formed