Are There Dark Matter Galaxies? ft. Sarah Pearson from Space with Sarah
Δημοσιεύτηκε στις 20 Μαΐ 2017
We
know there’s dark matter, and there are galaxies, but are there
galaxies entirely made up of dark matter? Astronomer Sarah Pearson joins
Fraser to talk about what’s out there.
Visit Space With Sarah's Channel:
https://www.youtube.com/channel/UCGoz...
Support us at: http://www.patreon.com/universetoday
More stories at: http://www.universetoday.com/
Follow us on Twitter: @universetoday
Like us on Facebook: https://www.facebook.com/universetoday
Google+ - https://plus.google.com/+universetoday/
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Team: Fraser Cain - @fcain / frasercain@gmail.com
Karla Thompson - @karlaii
Chad Weber - weber.chad@gmail.com
One
of the things I love about astronomy is how it’s rapidly changing and
evolving over time. Every day there are new discoveries, and
advancements in theories that take us incrementally forward in our
understanding of the Universe.
One of the best examples of this
is dark matter; mysterious and invisible but a significant part of the
Universe and accounting for the vast majority of mass out there.
It
was first theorized almost 100 years ago when astronomers surveyed the
total mass of distant galaxy clusters and found that the visible mass we
can see must be just a fraction of the total material in the clusters.
When you add up the stars and gas, galaxies move and rotate in ways that
indicate there’s a huge halo of invisible matter surrounding it.
Some
of the best evidence came from Vera Rubin and Kent Ford in the 60s and
70s, when they measured the rotational velocity of edge-on spiral
galaxies. They estimated that there must be about 6 times as much dark
matter as regular matter.
Dark matter became a serious mystery in
astronomy, and many observers and theorists have spent the last half
century trying to work out what it is.
And dark matter hasn’t
given up its secrets easily. Originally, astronomers thought it might
not actually be invisible mass, but a misunderstanding of how gravity
works at the largest scales.
But over the last few decades,
techniques have been developed, using the gravity of dark matter itself
to measure how it bends light from more distant objects. Astronomers
don’t know what dark matter is, but they’re able to use it as a
telescope. Now that’s impressive.
They’ve found amazing features
in the dark matter web out there, vast walls and filaments defining the
largest scale structures in the Universe. Clusters where dark matter and
its gas have been separated from each other.
Remember, we are at
the cutting edge of this mystery, and you’re watching it unfold in real
time. 25 years from now, I’m sure we’ll look back at our quaint
attempts to understand dark matter.
One of the most interesting
questions I have right now is: could there be dark matter galaxies?
Completely invisible to our eyes, but able to interact through gravity?
Of
course, in times like this, I like to bring in a ringer. Someone who
has dedicated their life to the study of these questions.
And
today, I’ve got with my Sarah Pearson, a graduate student in astronomy
at Columbia University and the host of “Space with Sarah”. Sarah studies
the formation and interactions of dwarf galaxies surrounding the Milky
Way to understand how galaxies built up at the earliest times in the
Universe and form the large galaxies we see at present day.
Sarah, welcome to the Guide to Space:
Sarah: Hi Fraser, thanks.
Fraser: Can you talk a little bit about how astronomers map out the distribution of dark matter in the Universe?
Sarah:
Yes, definitely. So that is a hard question, as you just explained, we
don’t see the dark matter. But one assumption about the Universe we live
in is that the light matter or baryonic matter. For example, what you,
me and stars consist of, and also galaxies, kind of trace out where the
dark matter is located.
So one assumption is that the light
matter follows the dark matter. In that way we can actually map out to
huge distances, kind of how galaxies and clusters of galaxies are
located in our Universe. And we imagine that the dark matter structure
is somewhat similar.
And also recently, very large scale
structure simulations of our own Universe have addressed this by kind of
starting out with an almost uniform distribution of dark matter in the
very early Universe. And what they see is when they let the Universe
evolve in time, for example, when the Universe is expanding, you kind of
have these dark matter clumps forming into galaxies in all these
filaments that you discussed.
You can kind of trace out the
location of dark matter by understanding the expansion of space versus
gravity that creates the galaxies that we see.
know there’s dark matter, and there are galaxies, but are there
galaxies entirely made up of dark matter? Astronomer Sarah Pearson joins
Fraser to talk about what’s out there.
Visit Space With Sarah's Channel:
https://www.youtube.com/channel/UCGoz...
Support us at: http://www.patreon.com/universetoday
More stories at: http://www.universetoday.com/
Follow us on Twitter: @universetoday
Like us on Facebook: https://www.facebook.com/universetoday
Google+ - https://plus.google.com/+universetoday/
Instagram - http://instagram.com/universetoday
Team: Fraser Cain - @fcain / frasercain@gmail.com
Karla Thompson - @karlaii
Chad Weber - weber.chad@gmail.com
One
of the things I love about astronomy is how it’s rapidly changing and
evolving over time. Every day there are new discoveries, and
advancements in theories that take us incrementally forward in our
understanding of the Universe.
One of the best examples of this
is dark matter; mysterious and invisible but a significant part of the
Universe and accounting for the vast majority of mass out there.
It
was first theorized almost 100 years ago when astronomers surveyed the
total mass of distant galaxy clusters and found that the visible mass we
can see must be just a fraction of the total material in the clusters.
When you add up the stars and gas, galaxies move and rotate in ways that
indicate there’s a huge halo of invisible matter surrounding it.
Some
of the best evidence came from Vera Rubin and Kent Ford in the 60s and
70s, when they measured the rotational velocity of edge-on spiral
galaxies. They estimated that there must be about 6 times as much dark
matter as regular matter.
Dark matter became a serious mystery in
astronomy, and many observers and theorists have spent the last half
century trying to work out what it is.
And dark matter hasn’t
given up its secrets easily. Originally, astronomers thought it might
not actually be invisible mass, but a misunderstanding of how gravity
works at the largest scales.
But over the last few decades,
techniques have been developed, using the gravity of dark matter itself
to measure how it bends light from more distant objects. Astronomers
don’t know what dark matter is, but they’re able to use it as a
telescope. Now that’s impressive.
They’ve found amazing features
in the dark matter web out there, vast walls and filaments defining the
largest scale structures in the Universe. Clusters where dark matter and
its gas have been separated from each other.
Remember, we are at
the cutting edge of this mystery, and you’re watching it unfold in real
time. 25 years from now, I’m sure we’ll look back at our quaint
attempts to understand dark matter.
One of the most interesting
questions I have right now is: could there be dark matter galaxies?
Completely invisible to our eyes, but able to interact through gravity?
Of
course, in times like this, I like to bring in a ringer. Someone who
has dedicated their life to the study of these questions.
And
today, I’ve got with my Sarah Pearson, a graduate student in astronomy
at Columbia University and the host of “Space with Sarah”. Sarah studies
the formation and interactions of dwarf galaxies surrounding the Milky
Way to understand how galaxies built up at the earliest times in the
Universe and form the large galaxies we see at present day.
Sarah, welcome to the Guide to Space:
Sarah: Hi Fraser, thanks.
Fraser: Can you talk a little bit about how astronomers map out the distribution of dark matter in the Universe?
Sarah:
Yes, definitely. So that is a hard question, as you just explained, we
don’t see the dark matter. But one assumption about the Universe we live
in is that the light matter or baryonic matter. For example, what you,
me and stars consist of, and also galaxies, kind of trace out where the
dark matter is located.
So one assumption is that the light
matter follows the dark matter. In that way we can actually map out to
huge distances, kind of how galaxies and clusters of galaxies are
located in our Universe. And we imagine that the dark matter structure
is somewhat similar.
And also recently, very large scale
structure simulations of our own Universe have addressed this by kind of
starting out with an almost uniform distribution of dark matter in the
very early Universe. And what they see is when they let the Universe
evolve in time, for example, when the Universe is expanding, you kind of
have these dark matter clumps forming into galaxies in all these
filaments that you discussed.
You can kind of trace out the
location of dark matter by understanding the expansion of space versus
gravity that creates the galaxies that we see.
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