Speaker
Description
The nature of dark matter (DM) is one of the biggest open questions in modern astrophysics. A crucial role in establishing this problem was played by radio observations of the 21-cm line of atomic hydrogen (HI), which revealed that the HI rotation curves of galaxies remain flat out to large radii, well beyond their stellar components. In synergy with near-infrared images that probe the stellar mass distributions of galaxies, HI rotation curves continue to be a major tool to test different DM models, galaxy formation models, and modified gravity theories. A key step in this context was the SPARC (Surface Photometry and Accurate Rotation Curves) project, which provided HI rotation curves and mass models for 175 disk galaxies at z = 0. However, SPARC has several limitations, such as data heterogeneity and limited statistics, which prevents more powerful tests of ΛCDM and alternative theories. To address these issues, I am working on the successor database BIG-SPARC, which combines spatially resolved HI data for almost 4,000 galaxies with WISE near-infrared photometry. The HI data for BIG-SPARC come both from public telescope archives (ASKAP, ATCA, GMRT, VLA, WSRT), as well as from the Apertif survey, which is the largest contributor. This new database increases the sample size of SPARC by a factor of more than 20, therefore allowing us to test different DM models and modified gravity theories with unprecedented statistical power. Nevertheless, BIG-SPARC represents just a small, intermediate step on the way to a further order-of-magnitude increase in sample size from potential future HI surveys with SKA-MID AA*.
| Topics | Galaxy Evolution & AGN |
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