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Black Hole Roundup

The views expressed are those of the author and are not necessarily those of Scientific American.


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Spinning black hole (NASA)

Black holes, black holes, and more black holes. In the past few weeks I’ve been thinking, talking, and even dreaming about black holes (yes really, somnolent thoughts seem well suited to these fantastic objects). Mostly this has been an effect of my book Gravity’s Engines hitting the shelves, but it’s also because barely a day seems to go by without some new piece of astrophysical research on these most dense and fantastic objects. Here’s a quick round up of a couple items.

A new survey containing the locations of about 2.5 million supermassive black holes was released a couple weeks back that used the full sky map obtained with NASA’s WISE (Wide-Field, Infrared Survey Explorer) mission to track down the pinpoints of thermal radiation from dust enshrouded holes in distant galaxies. These holes are consuming matter and as that matter plunges and spirals towards the event horizon it gets hot and energy is released. Much of the energy is in photons of light, these batter against the thick dust and gas in some galaxies, warming it up and producing what is in effect an afterglow of infrared light.

Each circle denotes an eating, energy producing black hole in the center of a distant and dusty galaxy (NASA/JPL-Caltech/UCLA)

These dusty galaxies, with their central supermassive holes, are located throughout the universe. In the WISE data they go back as far as 10 billion light years. While we’ve known that almost every galaxy in the universe contains a massive black hole at the center, this is the first systematic catalog of holes in these more elusive dust-rich systems – opening the door to a better understanding of the remarkable co-evolution of galaxies and their central beasts.

These results cropped up in conversation last week during a radio interview I did with The Daily Circuit on Minnesota Public Radio, you can listen in here:

Artist's impression of a big growing galaxy with big growing black hole (spewing jets of subatomic particles) (Credit:ESA/NASA/RUG/MarcelZinger)

Another exciting new piece of black hole research appeared this week. Astronomers using the Herschel space observatory – also capable of peering deep into dusty parts of the cosmos – found that some of the most powerful and distant examples of supermassive black hole energy output (so-called radio galaxies) are also home to colossal amounts of stellar birth. Herschel’s ability to look at the far infrared part of the electromagnetic spectrum lets us see stuff that appears dark and boring in regular visible light telescopes. In this case the thermal radiation reveals that these galaxies are growing their central black holes simultaneously with most of their stars. In fact hundreds of new stars are being formed every year in these places – an incredible amount if you consider that our Milky Way is lucky if it squeezes out one or two new stars a year today.

 

It's the red one. A doomed solar system? (Credit: ESO)

And finally, you may recall some exciting discussion a while back about the possibility that a recently spotted star or blob of interstellar material appears to be en route to a near pass to the 4 million solar mass black hole at the center of the Milky Way in 2013. A new paper appeared a couple weeks back that proposes this object is in fact a baby solar system, a young star with a surrounding disk of gas and dust that is already being shredded by gravitational tides in the galactic center. The authors contend that conditions suitable for stars and planets to form  exist beyond about a tenth of a light year from the central black hole – a notion that has been discussed for a while, following observations of a ‘ring’ of young stars orbiting the central black hole at these distances. A baby star that gets jostled into a path falling towards the black hole will get its proto-planetary baggage of material torn apart by gravitational tides in a way that at least superficially seems to match our observations of the current ongoing slow-motion crisis.

It may well be correct. And the authors point out a number of consequences of galactic-center planetary systems, including a supply of smaller comets and asteroids that could be seen as brief flares of energy when the black hole has its way with them. For those planetary systems that stay safely in orbit a few tenths of a light year away we can only speculate as to whether there might be living things gazing at such a truly awesome sight in their skies.

Caleb A. Scharf About the Author: Caleb Scharf is the director of Columbia University's multidisciplinary Astrobiology Center. He has worked in the fields of observational cosmology, X-ray astronomy, and more recently exoplanetary science. His books include Gravity's Engines (2012) and The Copernicus Complex (2014) (both from Scientific American / Farrar, Straus and Giroux.) Follow on Twitter @caleb_scharf.

The views expressed are those of the author and are not necessarily those of Scientific American.



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  1. 1. Bozobub 11:44 am 09/20/2012

    While I agree that there certainly COULD be life in one of those solar systems, a couple caveats come to mind:
    - Most black holes put out a *lot* of ionizing radiation; a tenth of a LY isn’t much, vs. the radiation coming from the accretion disc.
    - Most of the stars orbiting a black hole in this manner are (according to what I read here) rather young.

    Link to this
  2. 2. Caleb A. Scharf in reply to Caleb A. Scharf 4:17 pm 09/20/2012

    I’d agree with both those points (I was really just trying a little poetic speculation!). The galactic center is probably not the best place for life – at least based on a number of templates that we associate with habitability.

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  3. 3. jonathanseer 7:23 pm 09/20/2012

    When will astronomers banish the racist term “black holes”.

    The politically correct term should be “a hole of color”

    (joke)

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  4. 4. Knyaz 5:35 am 09/21/2012

    Возможно чёрные дыры это место перехода галактик из одного измерения в другое а миры других измерений мы видим как тёмную материю.

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  5. 5. jtdwyer 3:01 pm 09/21/2012

    As to the last item, there still seems to be some discussion as to the source of the infalling gas cloud, and whether or not it contains a star (much less planets) – see http://www.nature.com/news/gas-cloud-hurtling-towards-milky-way-s-black-hole-may-harbour-young-star-1.11351

    BTW, don’t almost all collapsing solar nebulae (‘nebulas’ is also correct, astronomers) eventually producing main-sequence stars necessarily produce protoplanetary disks? As I understand, the presence of a protoplanetary disk is a prerequisite for but not evidence of the development of planets… Please see http://en.wikipedia.org/wiki/Protoplanetary_disk

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  6. 6. JacobTh 12:18 pm 11/13/2014

    Long winded, and not-so-greatly written

    There’s been something (well a few things) on my mind ever since I took my first Astronomy class back in 2013: Instead of the Universe expanding, might the “Universe” be a Black Hole that we are in, such that it seems we are “expanding”? Although I have very limited knowledge about astronomy, I like to think that this is plausible. The main reason for this idea sprouted from “Galaxies that are (relatively) far from each other, accelerate away from each other” as the Universe “expands”. We know, or at least guess with good probability, that “stuff” that enters black holes accelerates faster and faster the closer it gets to the center.

    For example, there are 3 galaxies in the Universe: Galaxy A (closet to the “center”), Galaxy B (between galaxies A and C), and Galaxy C (furthest from the center-closest to the era where photons could travel freely).
    From our perspective (Galaxy B) galaxies A and C seem to accelerate away from us in different directions as the Universe expands, perhaps North and Southward (assuming we are oriented in a linear fashion). However, let’s apply the tidbit we know about Black Holes concerning that something closer to the center of a black hole will accelerate faster than something closer to the event horizon (assuming inside the black hole).
    Here we see something very similar, maybe identical, happening when comparing Universal expansion and Black Holes: objects appear to accelerate away from each other at increasing speeds the further they are from one another.
    I just wanted to get this thought out there. I know it’s not too well thought out, and I will refine the hypothesis to include much more, but I would like others to at least think about the idea that the Universe is actually a black hole.

    Link to this

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