Magnifying galaxies (3/30/23)

Good afternoon, and happy Thursday. If you look toward the western horizon just after sunset this week, you’ve got a chance of seeing five planets align. Venus, Mars, and Jupiter will be pretty easy to spot, but to see the much dimmer Mercury and Uranus, you’re better off with a set of binoculars.

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Peering through the lens

An ultramassive black hole 33 billion times the mass of the Sun (that’s billion, with a B) has been spotted in a distant galaxy.

Despite its size, finding this black hole was no easy feat. It resides at the center of a galaxy 2.7 billion light years away—far more distant than most black holes identified and studied by astronomers.

By any measure, this black hole seems like it should be virtually undetectable. So how was it detected?

I spy with my little eye…In a study published yesterday in the Monthly Notices of the Royal Astronomical Society, researchers detailed their use of a technique called gravitational lensing to identify and characterize this massive black hole at the center of the galaxy Abell 1201 BCG.

Gravitational lensing is a natural effect that makes it possible to observe far more distant objects than we’d be able to otherwise. Here’s how it happens:

• Light from a very distant object travels through the universe toward an observer (us).

• On its way here, that light passes by an object with a powerful gravitational force, which bends the light like a magnifying glass.

• The light then continues on its journey to us, now altered and magnified by that strong gravitational force.

The result in telescope observations tends to be a warped, stretched image. The researchers applied advanced computer modeling techniques to these observations to settle on an explanation for the dramatic size of the black hole.

This lensing effect allows researchers to observe very distant objects in far more detail than they’d be able to otherwise. It’s a neat, convenient little trick of the universe. 

Looking deeper: The ability to see distant objects in such high detail with this magnification effect has led the researchers to hope for glimpses of even more difficult-to-detect objects, such as inactive black holes that have stopped accruing material and emitting strong X-ray and gamma ray signals.

“Most of the biggest black holes that we know about are in an active state, where matter pulled in close to the black hole heats up and releases energy in the form of light, X-rays, and other radiation,” said James Nightingale, a researcher at the Centre for Extragalactic Astronomy at Durham University and lead author on the study. “However, gravitational lensing makes it possible to study inactive black holes, something not currently possible in distant galaxies.”

The researchers hope that this approach—though naturally occurring—will help them to identify ever more distant black holes and celestial objects to uncover details about how they formed and appeared at the beginnings of the universe.

Other News from the Cosmos

• JWST measured the temperature of its first rocky exoplanet, TRAPPIST-1 b. The Earth-like exoplanet came in at ~230°C and doesn’t appear to have an atmosphere.

• The BOAT, i.e., Brightest of All Time, a celestial X-ray and gamma ray explosion that stunned astronomers last October, was likely the brightest burst of its kind since human civilization began.

• Galactic winds made up of charged particles and gasses play a major role in determining the distribution of materials in galaxies, just like winds on Earth.

• Neptunian asteroids come in a variety of shades of red, indicating that they formed at different distances from the Sun. Researchers believe that there are two distinct classes of these asteroids.

• Giant exoplanets have widely ranging chemical makeups, according to new JWST data.

Rachael's Recs

⏳ Primordial black holes: What’s older than the universe? 50 years ago, mathematician and astronomer Bernard Carr wrote an article in New Scientist about the then-current evidence for the existence of black holes. Now we know black holes exist, and Carr is back with another article in the same magazine—this time on the evidence for black holes that formed back when the universe was new and dark.

🧊 Yearning for Uranus: Last year, NASA released its decadal survey, which recommended the agency pursue a $4.2B mission to Uranus by 2032. To say the least, that’s an ambitious timeline and cost estimate for a flagship journey to the distant ice giant. In an article for Scientific American, reporter Shannon Hall dives into the obstacles facing NASA’s next big potential planetary science project.

The View from Space