Space Fans and welcome to the first Space
Fan News of 2012.
First up, the SETI astronomers have started
pointing their telescopes at the Kepler planet
candidates that you may remember were announced
in 2011.
It is generally thought, that in our search
for extra terrestrial intelligence, it makes
sense to look for those signs from planets
that are more like the Earth.
This doesn't mean that life can't form in
strange planets with harsh environments, but
when starting out, we should look in places
where we know live can evolve into a civilization
- places like the Earth.
While the Kepler team has not confirmed all
of these candidates - also called Kepler Objects
of Interest - as being Earth sized planets
within a habitable zone, the SETI team started
looking anyway.
Specifically, they are looking in a region
of the radio spectrum called the Terrestrial
Microwave Window.
These are the radio frequencies that can penetrate
the noise of both interstellar space and our
own atmosphere.
They are looking in a special narrow range
of frequencies within this window known as
the “Water Hole,” which if you watched
the movie 'Contact' you will find it significant
that these frequencies are around 21 cm where
spectral lines that are associated with the
disassociation of water are located.
The argument goes like this: since water is
presumed to be necessary for life to exist,
an alien civilization might choose to broadcast
their existence at this wavelength in an attempt
to find others.
That assumes, of course, that they are looking
in the first place and want to be found.
I know, it's a long shot, but hey, based on
what we know about life in the universe so
far, which is nothing, it's worth a try!
Anyway, after spending some months sifting
through data, they are publishing some of
the results.
They are not reporting any alien signals,
but they are finding some interesting characteristics
of some of the signals.
These are the results from KOI 817 and 812.
What's interesting about them, according to
the SETI team, is that these signals, while
nothing more than interference they are careful
to say, look similar to what we can expect
to see from a broadcasting civilization.
For example,
The signals have a narrow frequency as you
can see from the very thin line, much thinner
than atmospheric noise, and they are drifting
in frequency over time, which make them look
like diagnonal lines in these plots.
This is the signal shifting towards longer
or shorter wavelengths due to the doppler
effect of the motions between us and the Kepler
planets.
If you look carefully you can see that the
frequency starts in one location, then as
time passes, ends up at another frequency.
Which way this diagonal line points depends
on the actual motion of the planet at the
time these were recorded: if the planet is
moving towards us, the line drifts toward
shorter wavelengths, going away, towards longer
wavelengths.
So, while these signals are nothing but interference,
probably from us, these results are promising
because they are a confirmation that the algorithms
they are using to find these telltale signs
of life appear to be working as they continue
their analysis on other Kepler Objects of
Interest.
Next, astronomers have discovered that there
were supermassive black holes in the universe
much earlier than expected, as early as 700
million years after the Big Bang.
What's surprising about this is that supermassive
black holes become supermassive only after
lots and lots of galaxy collisions, with the
black hole getting bigger after each collision
as the previously two black holes merge into
one.
When the universe was a few hundred million
years old, the first stars and galaxies were
just forming.
Everything was just starting out: stars, galaxies,
even black holes.
It has always been thought that most black
holes from this period in the universe's history
would be small because they wouldn't have
had a chance to gobble up enough material
to become supermassive.
Well, it turns out that is not the case.
Using observations from the Sloan Digital
Sky Survey, astronomers found supermassive
black holes at a time when the universe was
less than 1 billion years old.
They were the same size as today's most massive
black holes, which have had 13.6 billion years
to form.
So this was strange.
How could there be such big black holes from
so early when it takes the whole age of the
universe for others to reach the same mass?
So this discovery was very surprising.
For those who don't know, there are two main
classes of black holes: stellar-sized ones
that are around 30 times larger than the Sun
and are roaming around inside our galaxy.
The second type is way more massive.
These are usually found in the centers of
galaxies and are billions of times larger
than the mass of the Sun.
These supermassive black holes are the largest
in the universe and are believed to form from
the collisions of galaxies when their central
black holes combine into a larger one.
As more collision occur, the black hole gets
larger and larger.
The problem though, is that in the first few
millions of years after the Big Bang, galaxies
were too few and too far apart to merge.
So to find out how these black holes could
form so early, astronomers ran a massive simulation
to try to understand the observations from
Sloan.
This simulation was so sophisticated that
it allowed them to zoom in on interesting
events occurring while the simulation ran.
As they zoomed in to the creation of the first
supermassive black holes in their simulation,
they saw something unexpected.
Normally, in supermassive black holes we see
today, when cold gas flows toward a black
hole it collides with other gas in the surrounding
galaxy.
This causes the cold gas to heat up and then
cool back down before it enters the black
hole.
This process, called shock heating, would
stop black holes in the early universe from
growing fast enough to reach the masses found
in these observations.
Instead, no shock heating was occuring in
the early black holes.
They saw in their simulation thin streams
of cold dense gas flowing along the filaments
that give structure to the universe and straight
into the center of the black holes at very
high speed, feeding them at a fast rate, with
no shock heating.
This uncontrolled consumption caused the black
holes to grow exponentially faster than the
galaxies in which they reside.
So that's one possible explanation as to how
there could be such large black holes so early
in the universe.
One more cool thing came out of this: since
a galaxy forms when a black hole forms, these
results could also shed light on how the first
galaxies formed, giving us even more clues
as to how the universe came to be.
That's it for this week Space Fans, don't
forget next week is the AAS where I will post
a video a day from Monday to Thursday to talk
about the amazing discoveries and science
that's sure to come out of the meeting.
I can't believe we've been doing this for
an entire year!
Well, thanks for watching and, as always,
keep looking up!
