Wine and Cheese Fall 2024: Difference between revisions
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=16 September= | =16 September= | ||
==Priyanka Sarmah ()== | ==Priyanka Sarmah (Tsing Hua U)== | ||
'''Origin of a Strong Broadband 21 cm Cosmological Signal from Dark Matter Spin-Flip Interactions'''<br> | '''Origin of a Strong Broadband 21 cm Cosmological Signal from Dark Matter Spin-Flip Interactions'''<br> | ||
We explore a novel mechanism, where dark matter spin-flip interactions with electrons through a light axial-vector mediator could directly induce a 21 cm absorption signal which is characteristically different from the expected absorption features in the standard cosmology and in models with excess gas cooling, which have been broached to explain the recently observed anomalous signal in the EDGES experiment. We find generically that our model predicts a strong,broadband absorption signal extending from frequencies as low as 1.4 MHz (z~1000), from early in the cosmic dark ages where no conventional signal is expected, all the way up to higher frequencies where star formation and X-ray heating effects are expected to terminate the absorption signal. We find a rich set of spectral features that could be probed in current and future experiments looking for the global 21 cm signal. Large swathes of our model parameter space of interest are safe from existing particle physics constraints, however future searches for short range spin-dependent forces between electrons on the millimeter to nanometer scale have the potential to discover the light mediator responsible for our predicted signal. | We explore a novel mechanism, where dark matter spin-flip interactions with electrons through a light axial-vector mediator could directly induce a 21 cm absorption signal which is characteristically different from the expected absorption features in the standard cosmology and in models with excess gas cooling, which have been broached to explain the recently observed anomalous signal in the EDGES experiment. We find generically that our model predicts a strong,broadband absorption signal extending from frequencies as low as 1.4 MHz (z~1000), from early in the cosmic dark ages where no conventional signal is expected, all the way up to higher frequencies where star formation and X-ray heating effects are expected to terminate the absorption signal. We find a rich set of spectral features that could be probed in current and future experiments looking for the global 21 cm signal. Large swathes of our model parameter space of interest are safe from existing particle physics constraints, however future searches for short range spin-dependent forces between electrons on the millimeter to nanometer scale have the potential to discover the light mediator responsible for our predicted signal. | ||
Revision as of 16:31, 9 September 2024
This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Fall 2024.
Wine and Cheese sessions with one speaker will have a 50 minute talk with 10 minutes for questions. Sessions with two speakers will have two 25 minute talks, each with 5 minutes for questions.
Back to W&C Schedule
9 September
John Soltis (JHU)
Direct Estimation of Galaxy Cluster Mass Accretion Rate using Machine Learning
Galaxy cluster mass abundances provide an important cosmological constraint. Mass estimates, however, are biased by galaxy cluster dynamical state. The dynamical state, the intensity of physical disturbance in the galaxy cluster, is a direct result of its mass accretion rate. I will present a machine learning model for directly constraining the mass accretion rate of galaxy clusters from only X-ray and thermal Sunyaev-Zeldovich observations. Furthermore, I will discuss the different machine learning interpretability methods we employ to better understand the model, and the conclusions we draw from them.
Farhad Yusef-Zadeh (Northwestern)
Highlights of the MeerKAT Radio Survey of the Galactic Center
It has been 40 years since the magnetized radio filaments were first reported toward the Galactic center (GC), the first hint of an energetic activity in this region. Since then, a large number of synchrotron emitting filaments has been discovered in this high cosmic-ray pressure environment. In particular, the recent MeerKAT survey, which has been a gold mine in the study of the extreme environment of the GC, has increased the number of filaments by an order of magnitude. In this talk, I will discuss the statistical properties of the GC filaments, the comparison of the intracluster medium (ICM) and GC filaments, models of these enigmatic objects and the association of a milli-second pulsar powering a nonthermal radio filament near the magnetized Snake filament.
16 September
Priyanka Sarmah (Tsing Hua U)
Origin of a Strong Broadband 21 cm Cosmological Signal from Dark Matter Spin-Flip Interactions
We explore a novel mechanism, where dark matter spin-flip interactions with electrons through a light axial-vector mediator could directly induce a 21 cm absorption signal which is characteristically different from the expected absorption features in the standard cosmology and in models with excess gas cooling, which have been broached to explain the recently observed anomalous signal in the EDGES experiment. We find generically that our model predicts a strong,broadband absorption signal extending from frequencies as low as 1.4 MHz (z~1000), from early in the cosmic dark ages where no conventional signal is expected, all the way up to higher frequencies where star formation and X-ray heating effects are expected to terminate the absorption signal. We find a rich set of spectral features that could be probed in current and future experiments looking for the global 21 cm signal. Large swathes of our model parameter space of interest are safe from existing particle physics constraints, however future searches for short range spin-dependent forces between electrons on the millimeter to nanometer scale have the potential to discover the light mediator responsible for our predicted signal.
