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Week 2 of my Research Series!
Here are some acronyms I'll mention from now on:
GW -- Gravitational Waves
BBH -- Binary Black Hole
NSBH -- Neutron Star Black Hole
BNS -- Binary Neutron Star
Here are some acronyms I'll mention from now on:
GW -- Gravitational Waves
BBH -- Binary Black Hole
NSBH -- Neutron Star Black Hole
BNS -- Binary Neutron Star
LIGO -- Laser Interferometer Gravitational-Wave Observatory
SNR -- signal-to-noise ratio (i.e. how loud a waveform is compared to the data)
CBC -- Compact Binary Coalescence
SNR -- signal-to-noise ratio (i.e. how loud a waveform is compared to the data)
CBC -- Compact Binary Coalescence
Gravitational waves are Small ripples in spacetime caused by accelerating masses. They are detected by LIGO who has 2 4km arms in an L shape.
Credit: LIGO
Credit: LIGO
LIGO measures the changes in spacetime from GWs. The distances LIGO measures are equivalent to measuring the distance from here to Alpha Centauri (~4 light years) to the width of a human hair.
Credit: LIGO/T. Pyle
Credit: LIGO/T. Pyle
Detectors are located in Hanford, Washington and Livingston Louisiana.
Credit: LIGO
Credit: LIGO
To date LIGO has detected many BBH mergers, 1 NSBH merger, and 2 BNS mergers
LIGO uses waveform templates to detect gravitational waves. When there is a detection a specific waveform template will be the best match. This waveform template has given masses. From there more analysis can be done to analyze the parameters of the compact objects.
Stellar mass black holes have masses ranging from ~5 to ~100 solar masses. Neutron Stars have masses ranging from ~1 to ~2.16 solar masses.
Eccentricity is how much an object’s orbit deviates from a perfect circle. As the eccentricity increases ( → 1) the object becomes more of an ellipse. Eccentric GWs have strong GW emission on close passage and weak emission further apart. Credit: http://astronomy.swin.edu.au
All of the detections to date have been detected by circular binaries that have a constant GW emission
However, binaries with eccentricity could be detected in the future as better waveform models are developed, detectors are upgraded and/or new detectors are built
Here is an example of the difference between waveforms with a low eccentricity and a high eccentricity
I use PyCBC, a software package used to analyze the astrophysical sources of GWs, for analysis. It contains algorithms to detect GW from CBC and measures the parameters of the sources. It was used in the first GW detection and is still used to analyze LIGO/Virgo data.
