Primordial Gravitational Waves

Bryce Murphey & Chloe Arnold

SRJC - Physics 43 – Spring 2014 Teacher: Younes Ataiiyan

What are “Gravitational Waves”?

o Fluctuations of space time itself

o The waves propagated but do not cancel out or get absorbed by matter

How do we know they exist?

First theorized by Einstein’s field equations

The equations described how space-time and matter interact

Russel A. Hulse and Joseph H. Taylor first detected them

Detected them from a binary pulsar rotating around each other giving off gravitational waves and losing energy until they spiraled in together

Won the Nobel Prize in Physics in 1993 for this

“Primordial” Gravitational Waves

Quantum fluctuations of gravity before inflation

When the universe was about 10-35 seconds old

Fluctuations about 1/100th of a Planck scale

At inflation, when the universe rapidly expanded, these quantum fluctuations expanded to the scalable universe

Correlate closely with density waves

Certain locations in the universe have higher temperatures which have more stellar objects (galaxies, stars, nebulas, etc.)

Scientists are currently looking at the relationship between fluctuations in density and temperature and these gravitational waves

How were they discovered?

Telescopes BICEP1 and BICEP2

BICEP: Background Imaging of Cosmic Extragalactic Polarization

Both reside at the South Pole

Closest thing to being in space while on the ground

Six months of night keeps the air a steady cold temperature

There are minimal particles in the air to interfere with the EM radiation from space

BICEP2 Facility

How were they discovered?

Physicists looked at the polarization of the cosmic background radiation

They took analytical snapshots of the radiation in a select area of space that was largely devoid of foreground radiation and gravitational effects from our Milky Way Galaxy

They found the polarization to be in a B-mode pattern, which is often associated with magnetic fields

Analyzing small fluctuations (1 part in 30,000: Temperature to Gravity) in the gravitational field helped produce the popular B-mode image

This study was just released in March 2014

Cosmic Microwave Background Radiation

B-Mode Polarization (Primordial Gravitational Waves)

Issues? Only a select frequency (150 GHz) was used in finding these waves

If these are really primordial waves, the polarization would exist at ever frequency

The area they used is known for having galactic radio loops – this was not include in foreground calculations

Radio loops produce synchrotron emission because of charged particles from cosmic rays gyrating inside the magnetic field of ancient supernova shockwaves

Galactic dust can contain iron which aligns with magnetic fields and can produce polarized radiation

On Next slide: The blue lines are radio loops, the colored section is the area they researched

Radio Loops

What could this mean for Physics?

Supports the idea of inflation

Inflation seems to have occurred at 1/100th of the plank scale, typical with unification

Our current unified field theories require more information with reference to the early stages of the universe

Any time prior to 380,000 years after the Big Bang is indistinguishable since a point-source of light is one dimensional

Bibliography

http://www.ted.com/talks/allan_adams_the_discovery_that_could_rewrite_physics#t-87884

http://www.caltech.edu/content/bicep2-discovers-first-direct-evidence-inflation-and-primordial-gravitational-waves

http://www.ligo.org/news/bicep-result.php

http://news.stanford.edu/news/2014/march/physics-cosmic-inflation-031714.html

http://physicsworld.com/cws/article/news/2014/apr/10/have-galactic-radio-loops-been-mistaken-for-b-mode-polarization

https://www.youtube.com/watch?v=q702wxf_OPw