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Dark Matter – A Particle Physicist's Perspective Matthew Kirk – Physics, PhD

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Page 1: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Dark Matter – A Particle Physicist's Perspective

Matthew Kirk – Physics, PhD

Page 2: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Why do we need dark matter?

● First mentioned in 1930

● Swiss astronomer – Fritz Zwicky

● Used virial theorem to calculate mass of

galaxy

Page 3: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Why do we need dark matter?

● First mentioned in 1930

● Swiss astronomer – Fritz Zwicky

● Used virial theorem to calculate mass of

galaxy

● Factor of 500 different to expected result

Page 4: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Why do we need dark matter?

● Rotation curves – how fast stars orbit depends on

how far out they are

● First accurate measurement by Vera Rubin – 1970s

● Should fall off – but instead to flatten out

Page 5: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Why do we need dark matter?

Page 6: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Why do we need dark matter?

● Gravitational lensing

– Similar idea as virial theorem

– Gravity bends light passing near galaxy – how

much depends on how heavy the galaxy is

– Get a difference between what is seen and the

amount calculated

Page 7: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 8: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What do we know?

● Cosmic Microwave Background – Plank and

WMAP

● Dark Matter is around 26% of universe

Page 9: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 10: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What else have we seen?

● Excess of photons from the centre of the

galaxy

Page 11: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What else have we seen?

● Excess of photons from the centre of the

galaxy

● Excess of antiprotons compared to protons

Page 12: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 13: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What else have we seen?

● Excess of photons from the centre of the

galaxy

● Excess of antiprotons compared to protons

● Excess of positrons

Page 14: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What haven't we seen?

● Any “real” evidence down here on Earth!

Page 15: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What haven't we seen?

● Any “real” evidence down here on Earth!

● Direct detection limits keep on going down

Page 16: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What haven't we seen?

● Any “real” evidence down here on Earth!

● Direct detection limits keep on going down

● Except something odd perhaps in

– DAMA

– CoGeNT

– CDMS

Page 17: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 18: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 19: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 20: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09
Page 21: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What am I doing?

Page 22: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What am I doing?

● Looking at simplified models

– Single dark matter particle, single mediator

particle

Page 23: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What am I doing?

● Expect “new physics” to affect lots of “old

physics”

● What we haven't seen can be just as useful as

what we have

Page 24: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Thanks!

Page 25: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

Backup slides

Page 26: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09

What else have we seen?

● Excess of photons from the centre of the galaxy

● Excess of antiprotons compared to protons

● Excess of positrons

● Hints of self interaction between dark matter

particles?

Page 27: Dark Matter – A Particle Physicist's Perspectivekirkmatt/outreach/talks/... · 6/18/2015  · – CoGeNT – CDMS. What am I doing? ... Matthew Kirk Created Date: 6/18/2015 7:11:09