Astronomers unveil strong magnetic fields spiraling Milky Way's black hole | Hacker News Reader

Astronomers unveil strong magnetic fields spiraling Milky Way's black hole

eventhorizontelescope.org

54 pointsh1fra15 comments

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Slightly offtopic:

Can "spiralling" be a transitive verb too?

Original article title:

> Astronomers Unveil Strong Magnetic Fields Spiraling at the Edge of Milky Way’s Central Black Hole

HN title:

> Astronomers unveil strong magnetic fields spiraling Milky Way's black hole

You can spiral a football.

In that usage the object (football) ends up in the state of spiralling. So the HN title would, strictly speaking, mean that the magnetic fields are causing the black hole to spiral, which isn't right.

It's probably sort of being mixed up with the transitive verb "to circle", which goes the other way, with the subject ending up in a state of circling.

Is that so?

I was unfamiliar with football terminology so had to google it. Most references talk about "throwing a spiral" (noun), rather than "spiralling a football" (verb, transitive). But I can imagine this being a common usage. I have heard similar terms in other sports where you "verb" the ball, instead of throwing or bowling a "noun" :)

So I presume when a player "spirals a football" it means the player imparts a spin to the ball. (As opposed to player moving his/her own body around the ball in a spiral path :) )

Whereas the HN title uses it in a slightly different (second) sense -- "magnetic fields spiraling Milky Way's black hole" meaning something like "magnetic fields moving around / orbiting the Milky Way's black hole"

Semantics. literally.

There's also the idea of things spiraling down a drain. In there, no action is imparted on the drain by the things. The object of the sentence refers to the location it is taking place.

Yes when used as an intransitive verb a lot of other meanings are possible I guess:

Spiralling at the edge of black hole.

Spiralling out of control.

Spiralling incessantly.

Transitive verb usage would be more restricted in what it can refer to.

If you use it as a transitive word and people understand what you meant then yes it can be a transitive verb - that's the only criteria. In this case I think most people would understand what you mean so yes.

I feel like we are in a cosmology Renaissance period. The JWST has brought me to tears. This image enthrals and inspires me to worship the power of our universe. I have been changed inside by seeing these things and I feel like we are just getting started.

"and I feel like we are just getting started"

I think once we have enough telescopes on the moon, free space or in earth orbit, then things might get on another level.

I mean, this is pretty amazing:

"The international collaboration is working to capture the most detailed black hole images ever obtained by creating a virtual Earth-sized telescope. Supported by considerable international investment, the EHT links existing telescopes using novel systems — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved."

But I imagine without the atmosphere in the way, things might be quite easier and clearer.

My dream would be seeing a telescope at the gravitational lensing point in our solar system. But thats beyond 500A

This image is not from the JWST.

I know.

Any chance they can deduce/estimate the intensity of that magnetic field ? Is it more or less than the magnetar's one ? I am very curious about this info and couldn't find it in the article.

They're trying; it's the subject of the second paper referenced at the end of the link above (direct link: <https://iopscience.iop.org/article/10.3847/2041-8213/ad2df1>, open access). It's a bit complicated but (for our galaxy's central SMBH, Sgr A), from simulations they have a confidence interval spanning a few tens of Gauss at significant radial distance to a few hundred Gauss near the event horizon, or an average somewhere below 30 Gauss. Early measurements of M87 (<https://iopscience.iop.org/article/10.3847/2041-8213/abe4de>) arrived at somewhere between one and thirty Gauss (on average) for that black hole.

By comparison, Earth's magnetic field is about 0.5 Gauss at the surface. So Sgr A's averaged magnetic field is strong compared to that. However...

The Earth's magnetic field strength increases with depth below the surface, reaching about 25 Gauss at the core, which is a lot less than near the horizon of Sgr A.

But sunspots are on the order of a thousand Gauss.

The strongest magnetic fields human technology has been able to generate is on the order of tens of millions of Gauss.

A magnetar's field strength is at least tens of billions of Gauss.

Our black hole has not been feeding recently (as in, for the past many thousands to millions of years dating from the view we have of it here and now), so doesn't have much matter around it to drive the field strength higher. M87* is not feeding much either. The best working model for magnetars describes an early non-equilibrum state for the magnetar in which at intermediate depth a complicated nuclear fluid acts as a proton-dominated superconductor. Flows within that fluid act as a dynamo (well, really a magnetohydrodynamic (MHD) generator) for the magnetic field. A significant accretion structure around a black hole can also act as as an MHD generator. Weakly feeding black holes lack such a structure.

Very interesting, thank you for this detailed answer !

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