Fermi at 2: still rocking the high-energy sky

By Phil Plait | September 15, 2011 6:30 am

Astronomers working with Fermi — a mission that is mapping the sky in gamma rays — have just released a new catalog of objects detected by the spacecraft. They’ve re-analyzed two years worth of data and have found nearly 2000 objects blasting out this super-high-energy form of light.

Here is the all-sky map they made from that data:

[Click to enhulkenate, and see a labeled version.]

The map is set up in galactic coordinates, so the Milky Way itself runs across the center. There are a lot of gamma-ray sources in our galaxy, most of which are bright simply because they’re close. Others are actually luminous sources like the Crab Nebula, various pulsars, and other violent objects. The map is very similar to one released by Fermi a while back, but this new one is more sensitive, and can see fainter objects.

About half the detected sources are active galaxies: distant galaxies with supermassive black holes at their hearts, actively gobbling down matter and spewing out vast amounts of energy in the process (black holes are sloppy eaters). The folks at Goddard Space Flight Center put out a nice, short video explaining this:

[High-res versions of the video are online.]

What’s even cooler is that for a lot of these sources, maybe half, we don’t know what the heck they are. We haven’t detected optical counterparts (or at some other part of the spectrum,) that lets us more easily identify them. They may be dust-enshrouded galaxies, or sources inside our galaxy, or something in between. The only way to know is to keep observing them with Fermi, and try with different telescopes too.

I worked on the education and public outreach on Fermi before it launched (when it was still called GLAST, as it always will be in my heart). I’m glad to see it still pumping out the science, and teaching us about the Universe. And the best part, of course, is the mystery it’s showing us. Gamma-ray astronomy only began a few decades ago and we’ve learned a huge amount, but we still have a long way to go.

Related posts:

Black hole erupts in a nearby galaxy
S marks the spot
Happy birthday GLAST/Fermi!
The hulking sky

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (9)

  1. Messier Tidy Upper

    So now we’re getting a Fermi-er grasp of understanding the Gamma–ray sky and the objects that light it up? 😉

    Marvellous! :-)

    black holes are sloppy eaters.

    Well sphaghetti(~fied stars & who knows what else) *is* one of the harder foods to eat cleanly. 😉

  2. Chris

    I always wondered if some of the gamma ray bursts we see are actually due to a distant alien war.

  3. @ ^ Chris : Given the staggeringly huge amount of energy* released in GRBs that would have to be some war indeed! 😮


    * From the BA blog item linked to my name :

    Let me put this in perspective for you. Imagine a one megaton nuclear weapon detonating. That’s roughly 50 times the explosive yield of the bomb dropped on Nagasaki. Devastating. The Sun, every second of every day of every year, gives off 100 billion times this much energy. That’s every second. A star is a terrifying object. In the few seconds that a gamma-ray burst lasts, it packs a million million million times that much energy into its beams. In other words, for those few ticks of a clock the GRB is sending out more energy than the Sun will in its entire lifetime. There is, quite simply, no way to exaggerate the devastation of a gamma-ray burst.
    – Phil Plait, ‘Naked eye visible GRB!’ [GRB 080319B] posted online 2008 March 20th, 9:41 AM.

    A Gamma Ray Burst can be described as “energetic” in much the same way that our universe is describable as “big” – inadequately! 😉

    PS. Perspective providing, hopefully :

    “1 million seconds is about 12 days.One billion seconds is about 31 years.”
    – Stephen Jones writing in the ‘Weekend Australian’ newspaper, 2011 April 9th-10th.

  4. katwagner

    I don’t think there’s a word in the dictionary that can describe how farking bad these GRBs are. I mean I got stuck in the Mount St. Helens ashcloud and I thought that was really big and bad.

  5. Keith Bowden

    “Space… is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space…”

  6. Matthias

    There have been a lot of all sky surveys recently:
    * Planck
    * Wise
    * Updated Fermi all sky map

    Would be ideal candidates for chromoscope.net unfortunately they are not included (Wise, Fermi (only the old all sky map)) or only in low resolution (Planck).

  7. WJM

    Am I the only one who says “gurb”?

  8. Infinite123Lifer


    I was there when Mount St. Helen’s blew. It seems like a dreamy memory. Raining ash, ash and more ash. It was a crazy ash time, and a crazy ash memory.

    @#5. 42

  9. Chris Winter

    Chris wrote (#2): “I always wondered if some of the gamma ray bursts we see are actually due to a distant alien war.”

    I had the same thought, back before it was settled that GRBs are way distant, like millions of light years out.

    I think it’s important to note that this post is not about bursters, but steady (AIUI) gamma-ray sources — at least steady on the time scale of years.


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