Like a lot of kids, I grew up reading about neutrinos
and people speculating about doing neutrino astronomy.
And here I am, doing neutrino astronomy, I feel like I need
to pinch myself. My name is Roopesh Ojha,
and I'm an astronomer working at the Goddard Space Flight Center.
I work with the Fermi Gamma-ray Space Telescope. What we
have been able to establish, for the first time, is an individual
blazar as a potential birthplace of an individual neutrino.
The Fermi Gamma-ray Space Telescope has an instrument called the Large Area Telescope, which
we use to monitor the gamma-ray sky-the highest-energy electromagnetic band.
And we just noticed that there was a tremendous
increase in the amount of gamma-ray light coming from this one extra-galactic blazar.
A blazar is an extremely powerful, variable,
galaxy that is powered by a supermassive black hole.
It went up not by a little bit, not by a few percent, it
went up, like, 15 to 30 times its average flux.
So we knew something was afoot, later on it
turned out to be coincident, both in time and in space, with
the neutrino that was detected by IceCube.
IceCube is a neutrino telescope located at the South Pole, or to be
more precise, under it.
It consists of over 5,000 detectors that are spread out into a
cube about a kilometer on each side.
It's the world's biggest and it's coolest telescope.
So a neutrino is an incredibly small
particle, it moves almost at the speed of light,
it is nearly massless, it's incredibly plentiful,
but, it's very, very hard to detect because it
will not interact with just about anything. If you could detect
them though, because they have traveled through the universe essentially undeflected,
they have information that you could not access in any other way.
IceCube has detected a handful of extremely energetic
neutrinos. One of them, which is called Big Bird, has an energy of
about 2 peta-electron volts. To give you an idea of how much energy
that is, it is about a million, million times the
energy of dental X-ray. IceCube sees too large
a patch of sky to let us determine exactly which blazar Big Bird
came from. The enormous increase in gamma-ray flux seen by
LAT and radio flux by other TANAMI telescopes let us finger
the exact blazar which is responsible for Big Bird.
We have long suspected that blazars are the birthplaces
of such neutrinos. What we have been able to establish, for the
first time, is an individual blazar as a potential
birthplace of an individual neutrino. This is the first time that we can point
and say "That blazar is where this neutrino came from."
Blazars are the brightest steadily shining
objects in the universe. However, many of the most basic questions
about them, such as what is producing this tremendous amount of
energy, remain open, and unanswered. The same process
that produces this neutrino could also produce gamma rays,
and that would move us closer to an understanding of emission from near black holes
in blazars. [Music]
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