Super zoom of galactic doom

By Phil Plait | October 5, 2007 1:14 pm

M87 is a monster galaxy, the nearest giant elliptical to the Milky Way and also the nearest "active galaxy": a galaxy whose nucleus appears to be superbright, emitting vast amounts of matter and radiation.

These AGs baffled astronomers for a long time, but now we understand the general scenario that leads to these galaxies having active nuclei. Every major galaxy has a supermassive black hole in its core, and as matter falls in it forms a flattened disk, called the accretion disk. The inner part of the disk is incredibly hot, and a witch’s brew of forces operates there. They combine to focus a titanic jet of matter and energy that screams out from the vicinity of the black hole.

M87 has a jet. A big one!

This newly released image
was taken in the radio part of the spectrum using a technique called interferometry, where the abilities of widely-separated telescopes can be combined. In this case, ‘scopes from around the planet were used to make a virtual ‘scope with an effective aperture the size of the Earth. It’s called the Very Long Baseline Array, or VLBA. In this image, the resolution is incredible; objects only one milliarcsecond can be separated. That’s like reading the letters on a coin located 200 kilometers away!

Usually, AGs emit two jets, one in each direction. However, M87’s jet is aimed almost directly more or less at us. That makes the counterjet difficult to see. Weirdly, relativity effects add in, making the counterjet almost invisible. It is just barely detectable in this observation.

Interestingly, the researchers who took these observations found that the jet is moving at only a few percent the speed of light, much slower than previously thought. This means that the relativistic effects aren’t particularly strong… so why is the counterjet so faint? Good question, and the answer isn’t obvious. Maybe the counterjet is intrinsically faint, or there isn’t as much material in it. This doesn’t throw all the old theories out the window — there are other explanations — but it does mean that we have a lot to learn about the inner workings of these complex beasts, and the galaxies which spawn them.

Speaking of which, M87 is amazing. It’s about 50 million light years away, and sits in the center of the Virgo cluster, a collection of many thousands of galaxies. Even at that distance it’s bright enough to see with small binoculars. M87 is so big because it probably ate lots of smaller galaxies, slowly growing in the process. The central black hole in the galaxy is about 3 billion times the mass of the Sun, almost a thousand times the mass of the Milky Way’s central black hole.

Years ago I worked on a series of Hubble ultraviolet images of the jet — there is so much energy in the jet we thought there might be antimatter in it, which would create a weird molecule called positronium which emits in the UV. We didn’t find any (we didn’t really expect to, but it was an interesting observation, and I was able to use it to map how the UV detectors behaved at different temperatures), but working on that data gave me a chance to study this very cool galaxy. Now when I see it though my own telescope, I have a little more appreciation for what looks like a simple fuzzy patch of light.


Comments (27)

  1. Navneeth

    M87’s jet is aimed almost directly at us

    If it’s (almost) aimed at us, then what is that long feature pointing away from M87?

  2. Dagnappit. I meant to change that before posting. :-) I fixed it. It’s actually about 40 degrees off from being right at us.

  3. Anne

    oo, positronium! Has anyone ever detected it directly? I know there are supposed to be pair plasmas near pulsars, but I don’t understand what conditions are necessary to prevent annihilation long enough for positronium to behave like an atom. (Were you actually looking for *molecular* positronium? Do they really form into molecule-like structures?)

  4. Helioprogenus

    Would the speed of rotation of the accretion disk effect the jet in any way? It’s probably counterintuitive, but it would seem like the faster the angular momentum, the tighter the jet that would be dispelled.

    Also, could the counter-jet be weaker in some way than the one we can visualize? I recall seeing jets from pulsars that are weaker in one direction then another, but I don’t know if that translates to similarities in jets from supermassive black holes.

  5. > (Were you actually looking for *molecular* positronium? Do they really form into molecule-like structures?)

    Molecular positronium doesn’t really make much sense. It’d be like asking for molecular electronium. (Am I correct in thinking positronium and anti-hydrogen [or for that matter any other anti-element]) are two entirely different things?

    > Dagnappit. I meant to change that before posting. I fixed it. It’s actually about 40 degrees off from being right at us.

    Well, okay, so we’re probably within the octant that it’s pointing. In nothing else, it’s an accute angle. It’s aiming right for us, assuming that it’s an exceptionally poor marksman. It just… keeps… missing… the… target!

    “Follow him!” “Sir, we have the advantag–” “FOLLOW HIM!”

    Now here’s a brain-busting Class III civilization theoretical structure for you: a Dyson sail positioned to catch and utilize the material in an active galaxy’s jet (for whatever reason). Just a thought.

  6. Remek

    Doesn’t seem to bode well for life (ok, for what we -Terrans- normally describe as “life”) around the M87 area. Unless, that is, if they’re close to perpendicular to the high-energy jets, or their planet/star has a strong enough magnetic field to diminish the energies their home galaxy (or if nearby M87 itself) emits to allow what we imagine life as to evolve.

  7. The idea of positronium is that instead of hydrogen, which is an electron bound to a proton, you have an electron and an antielectron (a positron). The positron has a positive charge, but is much less massive. It’s analogous to a hydrogen atom, but the light it emits is at different wavelengths (because the center of mass is halfway between the two particles, and not really close to the proton like a hydrogen atom). For those in the know, the Lyman alpha line at 1216 Angstroms for hydrogen is at twice that wavelength or 2432 Angstroms for positronium. That’s what we looked for. I figured we wouldn’t find it because the environment of the jet would blast such atoms apart, plus the thermal broadening of the line would make it impossible to find.

    Whatever. We didn’t find it. 😉

  8. Richard B. Drumm

    What do you make of this image of M87:

    It’s a VLA (as opposed to VLBA) NRAO image and danged if it doesn’t look like it’s spinning around! Like a fire hose that’s gotten away from the fireman and is soaking everybody with X-rays!
    Way frakkin’ cool!
    Rich in Charlottesville

  9. tacitus

    Here’s a fun bit of speculation about M87:

    M87: A Bull’s-eye for SETI?


    Postbiological life might operate (communicate, organize, travel, colonize) on a larger scale than a single galaxy—possibly on the scale of the supercluster. The most advanced postbiological civilizations in our Local Supercluster may have developed in the Virgo Cluster, a rich cluster where intergalactic communication and travel would be easiest. If these advanced civilizations wanted to contact new civilizations elsewhere in the Supercluster they might collectively broadcast from one central location, for the sake of efficiency and to make it easy to find. A powerful, centrally located beacon would tend to replace all others in the Supercluster. This could explain the failure of SETI. The most likely location for this beacon is the giant elliptical galaxy M87.

  10. Remek

    Oh for crying out load… if an ‘advanced civilization’ has progressed to the point they can utilize a massive black hole to send some type of signal, they’ve progressed way beyond the point of needing to even generate that type of “Hey, we’re here!” signal in the first place.
    Pretty obvious that the jet has been flowing (at least in the direction we can measure) for millions or billions of years.

    A sufficiently advanced civilization wouldn’t have to even bother with galactic nuclei…
    Just send out billions or trillions of probes, thousands or millions to every galaxy that can be detected, and see what there is to see. Doesn’t matter how far away they are – certain portions of the scientific population will constantly volunteer (or be volunteered) to enter long term statis to wait for their galactic probes’ data results – teams of entities waking/reentering stasis/re-awakening time after time as every new potentially interesting solar system is encountered. (Via onboard very, very smart AI, of course)

    They’ll have had lots of time – many billions of years to explore in that way. And it doesn’t matter if *we* detect any type of hardware or EM signals. They don’t care about contacting us anytime soon – they just want the probe data. Maybe a billion years from now a new “contact” probe will come back to see if anyone is left, and if it’s worthwhile to even start some kind of conversation.

  11. TAMU Student

    Tacitus, what is meant by ‘postbiological’ ?

  12. Brian G

    Was just looking at a few Doctor Who things on Wikipedia and saw that New Earth is located there. I just wonder where New Earth is in M87.

  13. bassmanpete

    energy that screams out from the vicinity of the black hole.

    Bad physics from the BA – in space, no one can hear you scream! Sorry, I couldn’t resist it :)

  14. andy

    In fact, M87 is a pretty good target for pixel microlensing surveys, which could result in detection of planets that are not only extrasolar, but in a completely different galaxy. See here.

  15. Spaceman Spiff

    As the link to the science paper in the BA’s article suggests, it is possible that they are measuring pattern speeds of bulk flow, and that the local microscopic motions are highly relativistic. In any case, the more detailed the data are, the more stringently our models are tested – science in action.

  16. Robert

    The technique of interferometry is awesome, and I think it is a great reason to go back and establish a semipermanent base on the moon. Think of the increased resolution if we could get an observatory on the moon (or in orbit around it). Or, we could launch a space observatory in a counter orbit around the sun, Think of the resolution when the earth and the space observatory are on opposite sides of the sun!

    Or maybe theres some technical limitation that I’m not aware of that would limit all this. But there you are.

  17. Gary

    How does one calculate the mass of the black hole in the center of M87?

  18. andy

    Imagine the view from a planet within a giant elliptical galaxy like M87. Since the galaxy is not a disc galaxy, there would not be a bright band of stars across the sky, but there is very little gas in giant ellipticals to absorb light. You may well get views similar to those in a globular cluster but without the perils of having close stellar encounters destabilising the planetary system. The starfield in the direction of the galactic centre would be incredible.

  19. Richard: in general, jets don’t get too far before getting blown around by the gas between galaxies. Some are all twisted up, while others “puff out” as the jet slows to a halt, making the image look like a 100,000 light year Q-tip. :-).

    Thing is, M87 sits at the gravitational center of the Virgo cluster, so it’s not moving relative to the cluster. I wonder if some other galaxy swept past it, causing the jet to bend around? Or it may just be motion of the gas between galaxies itself doing that.

  20. Barbara

    Could this be a creation event?

    Matter being created out of the negative energy C-field and ejectedc as a quasar?

    M87 has a blue spike coming out of its center and this spike contains a number of small, compact objects. Further out along the jet isa radio, X-ray galaxy (M 84) with swept back X-ray isophotes indicating travel out along the jet. It is closely accompanied by a high redshift (z ~ 1) quasar. Further out is a very bright radio, X-ray quasar with flanking quasars around z = 1. This is all set in an extended line of X-ray sources and older, more evolved galaxies!

  21. TAMU Student

    Barbara >

    I’m not certain what you mean, how can matter be created out of nothing?

    (And what’s the C-field?)

    Just curious what is meant.

  22. Will. M

    I Googled “postbiological” and got a PDF ( which I almost understand somewhat. After 3 pages or so it begins to describe a seventh level of evolutionary development called postbiological.
    I didn’t finish reading…

  23. Barbara

    TAMU student-

    “C-field” stands for Creation field. It is a scalar field.

    In the conditions of strong gravity obtaining in the neighborhood of compact massive objects the value of the field can be locally raised. This leads to creation of matter along with the creation of negative c-field energy. The latter also has negative stresses which have the effect of blowing the spacetime outwards (as in an inflationary model) with the result that the created matter is thrown out in an explosion.

    In such pockets of creation ( minibangs or mini-creation events). a an axi-symmetric (Kerr type) distribution would lead to jet like ejection along the symmetric axis. creation takes place in the vicinity of already present massive ob jects.

    Thus, galaxies beget galaxies!

  24. Barbara,

    Are you making up stuff? That sounds like randomly selected jargon and pseudojargon strung together.

    An axiometric (Kerr type) distribution would lead to a jet like ejection? Maybe with a flux capacitor utilizing dilithium crystals…

  25. Doodler

    With a central black hole reaching that size, is this thing verging on qualifying as a quasar?

  26. bob_co

    Is that enough resolution to see flags or footprints on the moon?

  27. ArchFerdinandDuke

    dilithium crystals, That was my thought too! Flux capacitor? naw not a chance. Wouldn’t work.


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