Monday Science Seminar

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4530 Sterling Hall
@ 12:00 pm - 1:00 pm

An informal seminar series to highlight work from early career researchers from institutions around the world.

Title: Multi-wavelength observation of hot galactic halos: a treasure trove of galaxies

Abstract: The hot circumgalactic medium (CGM) is believed to host most of the baryons and metals that are missing from the stellar disk and ISM. However, detecting the hot CGM is extremely challenging due to its low surface brightness and the complexity of the X-ray background. By carefully selecting an optimum target, devising an efficient and rigorous method, and performing two independent analyses of our Suzaku and XMM-Newton data, we have been able to detect the integrated emission of the hot CGM of an isolated star-forming spiral galaxy NGC 3221. The mass of the detected hot CGM is sufficient to account for the missing galactic baryons. The temperature of the hot CGM within 30-100 kpc of the stellar disk is super-virial and drops to the virial temperature beyond 100 kpc. It is the first and only L* galaxy (so far) with such intriguing findings. To complement observations of individual galaxies, we performed stacking analyses in mm using the thermal Sunyaev-Zeldovich Effect. We cross-correlated the WISE galaxy catalog with the Compton-y map derived from the CMB data of the Planck x Atacama Cosmology Telescope to estimate the thermal pressure of the CGM of 0.63 million z<0.3 L* spiral galaxies. We found that the thermal energy of the CGM of these galaxies evolves more strongly with mass than the self-similar relation of purely gravity-driven halos. We also detected a non-monotonic trend of baryon fraction as a function of mass, with a certain mass range being baryon sufficient. Our results provide insights into the impact of galactic feedback on the hot CGM and set a benchmark for designing next-generation X-ray and mm telescopes.

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Organized by: Leon Trapman, Dan Rybarczyk, Nickolas Pingel