A globular cluster (GC) is a tightly bound spherical collection of hundreds of thousands of old stars. The proper modelling of GCs can be difficult due to the high number of constituents, each interacting with one another. Accordingly, there are many different analytic and numeric GC models competing against each other. Thus, an efficient observational method is required to test these models, and to find the most realistic one. Electromagnetic observations are limited in this regard, because they cannot provide us information about the deeper structure of GCs. However, as we point out in this new study, detections of gravitational-waves (GWs) from eccentric binary black holes (EBBHs) could serve as a tool for testing and constraining these GC models.
EBBHs are expected to form in dense stellar systems, such as GCs. Properties of GCs affect the formation of EBBHs within them, and consequently, we may gain information about properties of GCs by detecting EBBHs and reconstructing their parameters. Our goal is to determine the minimal number of EBBH detections with GW detectors that allows testing implications of different GC models on the observable distribution of EBBH parameters, such as orbital eccentricity and pericenter distance at the time EBBH signals enter the sensitive band of Advanced LIGO (aLIGO). Our study is the first one that aims testing possible models of dense stellar environments using GW signals of EBBHs.
EBBHs are proposed to be sources of GWs detectable by aLIGO. These binaries are expected to be detectable from great distances due to the strength and spectral richness of their GW signal. When aLIGO reaches its full sensitivity, which is proposed to happen in 2019, the expected rate of EBBH observations will be 5-20/year. This detection rate can already provide enough data to carry out an actual test of GC models on a reasonable timescale.
In December 2015, I was awarded 3rd prize at the Conference of Scientific Students' Associations (the most famous and recognized competition in Hungary for undergraduate researchers). We are currently preparing a paper to be published in the near future.
- Noise analysis of the data of infrasound microphones working in the LIGO PEM system