Space Fan News #52: The Doom of Early Galaxies; Remembering Fallen Explorers

Uploaded by tdarnell on 27.01.2012

Hello Space Fans and welcome to another edition of Space Fan News.
First up, astronomers at the European Southern Observatory have pointed the massive LABOCA
camera installed on the 12 meter Apex radio telescope at very distant and very bright
galaxies from the early universe - around 10 billion years ago - in an attempt to learn
how they group together.
The LABOCA camera is essentially a 'thermometer camera' with 295 detectors and a field of
view of eleven and a half arcminutes and when used with Infrared telescopes like Spitzer
and ESO's Very large telescope, they can combine these images to get an idea of how much dark
matter surrounds these galaxies in a kind of halo.
Guess what they call that? Yep, dark matter haloes.
Now, you may be asking, 'Hey, if dark matter doesn't interact with us in any way, how can
we measure it?'.
That is a very good question, I'm glad you asked.
The answer of course is that they use a technique you've heard me talk about in almost every
episode it seems: gravitational lensing. Looking at the tiny distortions of light as it gets
bent around galaxies and subtracting the stuff we can see from that observation, tells us
something about how much dark matter is around the galaxy doing the lensing as well as where
the dark matter is.
So it turns out that the more closely the galaxies are clustered, the more massive their
halos of dark matter. Now remember, these galaxies were seen from the universe's distant
past, about 10 billion years ago. Back then, they were massive, active and much closer
At this time in the universe, these galaxies were burning through stars, literally. Star
formation in these early galaxies was so intense and so short (it lasted only 100 million years)
that they were able to DOUBLE the number of stars in these galaxies in that time.
Think about that: doubling the number of stars in a galaxy in only 100 million years. That
rate of star formation does not happen today. These galaxies, by the way, are called starburst
So starting with these measurements of the mass of the early galaxies and their dark
matter halos from 10 billion years ago, and then running a simulation to what estimate
what they would look like today, astronomers found that these early galaxies - active,
and going crazy - these galaxies eventually become giant elliptical galaxies — the oldest
and most massive galaxies we see in the universe today.
OK great. We know a lot now: we know how much mass these galaxies had 10 billion years ago,
we know their approximate rate of star formation, and our fancy algorithm tells us that after
10 billion years they become gigantic elliptical galaxies.
So THIS research is the first to show this clear link between the most energetic starbursting
galaxies in the early Universe, and the most massive galaxies in the present day.
But wait a minute, why does this period of rapid star formation end after only 100 million
years? What would cause that?
Well, again, these guys might have an answer.
At that stage in the history of the cosmos, the starburst galaxies are clustered in a
very similar way to quasars, indicating that quasars are found in the same dark matter
Quasars are among the most energetic and brightest objects in the Universe, they are huge galactic
beacons that emit intense radiation. And... They are powered by a supermassive black hole
at the center of the galaxy.
There is mounting evidence to suggest the intense starburst period in these galaxies
also powers the quasar by shoving enormous quantities of material and stars down the
black hole's throat. This fuels the quasar which in turn emits powerful bursts of energy
that are believed to blow away the galaxy’s remaining gas, which is the raw material for
new stars.
And this effectively shuts down the star formation phase for that galaxy, leaving behind an enormous,
old and comparatively dead elliptical galaxy that we see today.
So basically what they are finding is that these young galaxies are sealing their fate.
Stars are born very fast, feed a black hole which powers a quasar which then blows away
any remaining gas to make new stars with.
Next, I want to take a minute to recognize the 45th anniversary of the Apollo 1 fire.
On this day in 1967, Gus Grissom, Ed White, and Roger Chaffee were killed when a fire
swept through their Apollo capsule while running some tests at Cape Canaveral.
At that time, the Apollo program was using pure oxygen in the spacecraft and a spark
flared during one of the tests, igniting the oxygen. All three men were killed.
When this happened, I was four years old and it was my very first encounter with anything
having to do with space (at least that I can remember). My earliest memory that I can trace
back to my interest in astronomy started on this day, when my mom and dad were watching
the news and the astronaut's pictures were on the TV and Walter Cronkite was explaining
what happened.
In the days and weeks and months that followed this tragedy, whenever I saw a Gemini capsule
or a man in a spacesuit on TV, I'd stop playing, or whatever I was doing, and watch. As I got
older, I watched the Apollo 11 landing and on THAT day, ever since, I knew what I wanted
to do with my life.
Since so many of NASA's tragedies seem to occur around this time of year, NASA has marked
the last Thursday in January (which was yesterday) as a day of remembrance to all those who have
lost their lives in America's Space Program.
Well, I'll leave
it there for this week space fans. Thank you for watching and, with all of these awesome
people in our hearts, Keep Looking Up.
You know, to this day I STILL get chills whenever I hear Walter Cronkite's voice on a documentary
or something. I really miss the days of Apollo.