APOD: Dancing Ghosts: Curved Jets from... (2021 Sep 01)

[APOD Robot]

Dancing Ghosts: Curved Jets from Active Galaxies

Explanation: Why would galaxies emit jets that look like ghosts? And furthermore, why do they appear to be dancing? The curled and fluffy jets from the supermassive black holes at the centers of two host galaxies (top center and lower left) are unlike anything seen before. They were found by astronomers using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope when creating maps tracing the evolution of galaxies. Images preceding this Evolutionary Map of the Universe survey only showed amorphous blobs. Eventually, comparisons of relative amounts of energy emitted revealed the glowing elongated structures were created by electrons streaming around magnetic field lines</a>. Overlaying the radio data on an optical view of the sky (Dark Energy Survey) confirmed that the electron streams originated from the centers of active galaxies. Usually such Active Galactic Nuclei (AGN) produce straight jets. A leading hypothesis for the geometric origin of these unusually graceful shapes involves the flow of large-scale intergalactic winds.

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[JohnD]

Could the BHs emitting those jets be tumbling, precessing, so that instead of a straight jet along the axis, the direction varied with time?
This is happening to V404 Cygni : https://earthsky.org/space/black-hole-v ... rby-space/

[neufer]

Could the BHs emitting those jets be tumbling, precessing,
so that instead of a straight jet along the axis, the direction varied with time?

This is happening to V404 Cygni : https://earthsky.org/space/black-hole-v ... rby-space/

• That would have been my default position:

It would be unusual for the plane of the accretion disk to align with the rotation equator of the BH.
Frame dragging of the the accretion disk & consequently of the jets is, no doubt, the norm:

<<The first frame-dragging effect was derived in 1918, in the framework of general relativity, by the Austrian physicists Josef Lense and Hans Thirring, and is also known as the Lense–Thirring effect. They predicted that the rotation of a massive object would distort the spacetime metric, making the orbit of a nearby test particle precess. This does not happen in Newtonian mechanics for which the gravitational field of a body depends only on its mass, not on its rotation.

Relativistic jets may provide evidence for the reality of frame-dragging. Gravitomagnetic forces produced by the Lense–Thirring effect (frame dragging) within the ergosphere of rotating black holes combined with the energy extraction mechanism by Penrose have been used to explain the observed properties of relativistic jets. The gravitomagnetic model developed by Reva Kay Williams predicts the observed high energy particles (~GeV) emitted by quasars and active galactic nuclei; the extraction of X-rays, γ-rays, and relativistic e−– e+ pairs; the collimated jets about the polar axis; and the asymmetrical formation of jets (relative to the orbital plane).>>

• However, the situation is probably much more complicated that just that:

In this X-ray (Chandra) and radio (VLA) composite image, hot matter (blue in X-ray) from the Virgo cluster falls toward the core of M87 and cools, where it is met by the relativistic jet (orange in radio), producing shock waves in the galaxy's interstellar medium.

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<<This image shows the eruption of a galactic "super-volcano" in the massive galaxy M87, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array (VLA). At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies.

The cluster surrounding M87 is filled with hot gas glowing in X-ray light (and shown in blue) that is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars.

However, radio observations with the VLA (red) suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed. The interaction of this cosmic "eruption" with the galaxy's environment is very similar to that of the Eyjafjallajokull volcano in Iceland that occurred in 2010. With Eyjafjallajokull, pockets of hot gas blasted through the surface of the lava, generating shock waves that can be seen passing through the grey smoke of the volcano. This hot gas then rises up in the atmosphere, dragging the dark ash with it. This process can be seen in a movie of the Eyjafjallajokull volcano where the shock waves propagating in the smoke are followed by the rise of dark ash clouds into the atmosphere.

In the analogy with Eyjafjallajokull, the energetic particles produced in the vicinity of the black hole rise through the X-ray emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake. This is similar to the hot volcanic gases drag up the clouds of dark ash. And just like the volcano here on Earth, shockwaves can be seen when the black hole pumps energetic particles into the cluster gas.>>

Image Credits: X-ray: NASA/CXC/KIPAC/N. Werner et al Radio: NSF/NRAO/AUI/W. Cotton>>

[orin stepanek]

DancingGhosts_EnglishNorris_960.jpg

Electrons around a magnetic field? Wonder if something similar could
be created in a laboratory?

[Chris Peterson]

Electrons around a magnetic field? Wonder if something similar could
be created in a laboratory?

Sure. There are a variety of particle accelerator designs that produce synchrotron radiation.

[neufer]

Electrons around a magnetic field?

Wonder if something similar could be created in a laboratory?

Sure. There are a variety of particle accelerator designs that produce synchrotron radiation.

<<The Synchrotron Radiation Source (SRS) at the Daresbury Laboratory in Cheshire, England was the first second-generation synchrotron radiation source to produce X-rays. The SRS supported pioneering work on X-ray diffraction, structural molecular biology, surface physics and chemistry, materials science and upper atmosphere physics. A 'LOQ' (low tune) configuration also provides radiation bursts at 3.123 MHz (= c/96m : the revolution frequency of the electrons, corresponding to the 96 m circumference).>>

<<The Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Mid West region of Western Australia. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, with a 30 sq degrees FoV at 1.4 GHz.>>

[johnnydeep]

This snip from the PDF linked to in the description might be helpful:

dancing galaxy jet ghosts.JPG

So, are these jets actually interacting with each other or does it just look that way? How far apart are the source black holes?

[neufer]

So, are these jets actually interacting with each other or does it just look that way?

• The jet plasmas/magnetic fields are, indeed, actually interacting with each other.

How far apart are the source black holes?

• About 1.65 Mly such that the jet plasmas are about as long as
  the jet plasmas of Centaurus A (or, perhaps, as Matt Harding).