Description:

Tiffany Liou, Strom Research Group

“Harder, Better, Faster, Stronger : Warm-ionized Outflows at Cosmic Noon”

Star-formation and chemical evolution in galaxies is regulated by the inflow and outflow of material. Large scale galactic outflows driven by active galactic nuclei (AGN), core-collapse supernovae, and intense star-formation controls the amount of cold gas present in the central galaxy. The relationship between outflowing gas kinematics and global galaxy properties is essential for understanding the effects of stellar feedback. Outflows at low redshifts (z~0) are extensively studied and scaling relationships are well defined. However, scaling relationships become ambiguous at high redshifts due to the challenge of acquiring high signal-to-noise (SNR) spectra for outflow detection. Using deep spectroscopic data from the Keck Baryonic Structure Survey (KBSS) and Keck Lyman Continuum Survey (KLCS), we are able to increase the sample size of outflows at Cosmic Noon (z~1-3). In this talk, I will discuss how to extract outflow signatures from these data and how to establish new scaling relationships at Cosmic Noon. Our findings suggest a possible cosmic evolution in outflow strength, with high-redshift galaxies hosting significantly stronger outflows.

Asad Ukani, Murchikova Research Group

“Modeling Non-Keplerian Orbits Around the Milky Way Supermassive Black Hole”

The center of our Galaxy hosts a supermassive black hole (SMBH), Sagittarius A* (SgrA*). Owing to its proximity, the environment of SgrA* can be observed at much higher resolution than the nuclei of other active galaxies. Thus, it presents a unique laboratory for investigating open questions pertaining to SMBHs, including how they grow. SgrA* is surrounded by a dense nuclear star cluster (NSC), which consists of multiple stars that drive ionized winds towards the black hole. Several gas structures embedded within the NSC also supply matter to the SMBH. To characterize the resulting accretion flow, it is important to model the orbital dynamics of both the stellar sources and the infalling gas. Studies however commonly adopt the Keplerian approximation, neglecting the extended nature of the NSC. Here, we solve for the trajectories and quantify the apsidal precession of orbits in the combined potential of SgrA* and the cluster. Our framework provides a more physical model for fitting observational data, assessing angular momentum transport, and estimating accretion rates. Using this method, we also fit—for the first time—a non-Keplerian orbit to the circumnuclear disk, one of the largest reservoirs of molecular gas around SgrA*, and compare our results against observations.