천문우주과학과

일시:  2021년 11월 18일 목요일 오후 4시 
       (https://cnu-ac-kr.zoom.us/j/85399787326)

연사:  이재현 박사님(고등과학원)

제목: Jellyfish Galaxies – A Trace of Environmental Effects on Galaxies

 초록:  

   We investigate the impact of ram pressure stripping due to the intracluster medium (ICM) on star-forming disk galaxies with a multi-phase interstellar medium (ISM) maintained by strong stellar feedback. The disk galaxies are set to have two different initial gas fraction: normal and gas-rich cases. We carry out radiation-hydrodynamics simulations of the isolated disk galaxies embedded in a 1011M¤ dark matter halo with various ICM winds mimicking the cluster outskirts (moderate) and the central environment (strong). We find that both star formation quenching and triggering occur in ram pressure-stripped galaxies, depending on the strength of the winds. HI and H2 in the outer galactic disk are significantly stripped in the presence of the moderate winds, whereas turbulent pressure provides support against ram pressure in the central region where star formation is active. Moderate ICM winds facilitate gas collapsing, increasing the total star formation rates by ~40% when the wind is oriented face-on or ~80% when it is edge-on. In contrast, strong winds rapidly blow away neutral and molecular hydrogen gas from the galaxy, suppressing the star formation by a factor of two within 200Myr. Dense gas clumps are easily identified in the extraplanar regions of the galaxy with a normal gas fraction, but no significant young stellar populations are found in such clumps. On the other hand, dense molecular clouds form in-situ in the distant tail of the gas-rich galaxy. Furthermore, young stellar populations are born in the molecular clumps in the tail. Our results suggest that jellyfish features emerge when the ISM from gas-rich galaxies is stripped by strong ram pressure, mixes with the ICM, and enhances the cooling in the tail.