Dr. Valeria Olivares

X-Ray Cavity Dynamics and Their Role in the Gas Precipitation

I study the effect of the ICM ``weather'' on the AGN feedback and explore if such is necessary to produce multiphase condensation on a sample of nearby Planck selected galaxy clusters using Chandra observations. MUSE observations of 18 optical emitting clusters show that in most of the cases, the projected filaments appear to be located behind or around the bubbles, indicating that AGN feedback plays an important role in forming the warm filaments by likely enhancing turbulence or uplift. In a few cases the clusters either lack cavities or the connection with their cavities is vague, suggesting different turbulence-driven mechanisms (sloshing/mergers) or physical time delays involved.

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Black Hole Activity Not Evolving in Central Cluster Galaxies

We present a systematic study of X-ray cavities using archival Chandra observations of nearby galaxy clusters selected by their Sunyaev-Zel'dovich (SZ) signature in the Planck survey, which provides a nearly unbiased mass-selected sample to explore the entire AGN feedback duty cycle. Based on X-ray image analysis, we report that 30 of the 164 clusters show X-ray cavities, which corresponds to a detection fraction of 18%. After correcting for spatial resolution to match the high-z SPT-SZ sample, the detection fraction decreases to 9%, consistent with the high-z sample, hinting that the AGN feedback has not evolved across almost 8 Gyrs.

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Origin of the cold gas in Central Cluster Galaxies

Observations of cool-core cluster, show extended multi-phase filamentary around the brightest cluster galaxy of several kpc long. However, the origin of these filaments is still under discussion. Recent studied has suggested that these filaments are either formed by local thermal instabilities, due to turbulence motions (AGN feedback) or uplifted behind the buoyantly rising AGN bubbles the buoyantly radio bubbles. To study the formation these filaments we used multi-wavelength observations (ALMA, MUSE and Chandra).

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Origin of the cold gas in Central Group Galaxies

I extending the study of the origin of the cold gas to galaxy group cores (BGGs). Galaxy groups, representing the intermediate-mass range between individual galaxies and massive clusters, offer an interesting avenue for investigation. These systems are very diverse, and many of them have been observed to have a hot atmosphere. However, their low-velocity dispersion and small galaxy separation make mergers more prevalent than in clusters. We assembled the most significant sample of BGGs observed with MUSE. We trace, for the first time, the distribution and kinematics of the warm gas in a significant sample of galaxy groups core by using several optical emission lines.

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Sub-millimeter galaxies

During my Master's thesis, I studied the ionized warm phase of several sub-millimeter galaxies (SMGs) at high redshift. The goal was to understand the origin of the extreme star formation episodes observed in these fascinating systems. We conducted SINFONI/VLA observations targeting Hα in eight SMGs at z = 1.3-2.5. Our analysis involved mapping the spatial distribution and kinematics of the star-forming regions in these galaxies at kpc-scales. Through kinemetry analysis, we found that the majority of the sample did not exhibit rotation-dominated kinematics characteristic of a disk-like structure. Instead, irregular and/or clumpy velocity and velocity dispersion fields were observed, suggesting a scenario where these extreme star formation episodes are triggered by galaxy-galaxy interactions and major mergers. Learn more

Dr. Valeria Olivares