Speaker
Description
In the Lambda Cold Dark Matter paradigm, galaxy properties scale with those of their dark matter halo. As a galaxy’s stellar mass increases, one can expect a larger dark matter halo. When halo mass decreases, the efficiency at which stars form from the gas inside the halo also decreases, until star formation does not occur. This results in dark matter halos filled with atomic hydrogen (HI) and zero stellar mass. These objects have been dubbed dark galaxies and while they show up in cosmological simulations, and many groups have claimed to have observed them, there has been no concrete evidence of their existence. In its first data release, the FAST All Sky HI Survey (FASHI) measured the properties of 41 741 galaxies using the 21-cm radio emission produced by HI. Of these galaxies, 70 were found not to have optical counterparts and were thus called “dark galaxy candidates”. We obtained the properties and spectra for each of these dark candidates, comparing them to simulations and seeing if they would benefit from being followed up at higher sensitivity. We found that the vast majority of the 70 dark galaxy candidates did not agree with the predictions from modern cosmological simulations. We determined that it would be beneficial to follow-up each dark galaxy candidate with the Green Bank Telescope (GBT). This would allow us to obtain high sensitivity spectra to confirm the presence of these galaxies. Should these galaxies prove to exist, it would redefine the way we make cosmological simulations and allow us to better understand the large scale structure that governs our universe.
| What area of study best describes your talk? | Analysis |
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