Physics Dept Seminar

March 9, Monday

Field-Aligned Modelling of Solar Flares:

Testing Theories and Interpreting Observations

Dr. Graham Kerr

NASA Goddard Space Flight Center

(Theoretical Solar Physics, Host: Cao)

Time: 11:45 am - 12:45 pm with 11:30 am tea time

Room: ECE 202

Solar flares and coronal mass ejections (CMEs), together referred to as solar eruptive events (SEEs) are transient yet dramatic energy release events occurring in the solar atmosphere, representing extreme examples of various plasma physics phenomenon. They are also major drivers of geoeffective space weather. During SEEs a significant amount of magnetic energy is released, accelerating particles, causing in situ heating, and driving the release of CMEs. Understanding the fundamental physics of the energy release and transport during SEEs is key as we work towards predicting their occurrence.  Here I will focus on the flare part of SEEs, illustrating how we can study the solar atmospheres hydrodynamic and radiative response to flare energy injection to determine if our theories of flare energy transport are consistent with observations. With the fortune of increasingly high-quality data (both spaceborne and ground based, e.g. BBSO/GST and the upcoming DKIST)  comes the need for state-of-the-art numerical models to simulate flares, and forward model observables for model-data comparisons. These are required to both help extract and interpret what information observations carry, and (most importantly) to determine if theories stands up to the stubborn reality of observations. Magnetic field-aligned (i.e. 1D) loop models of solar flares allow us to study the detailed microphysics and complex feedback between radiation and hydrodynamics at the high spatial and temporal resolution demanded during flares. This is particularly true of the solar chromosphere and transition region, where the bulk of flare energy is deposited, and where the majority of the flaring radiative output originates. However, flares are, of course, 3D phenomena, so how can we bridge the gap from 1D to 3D as we work towards fully 3D flare models? In this seminar I will (1) summarise the current state of solar flare modelling, (2) show, using white light solar flares (WLFs) as an example, how critically attacking models with observations can indicate if new ingredients to theory are required, and (3) showcase recent efforts that aim to model optically thin emission that includes 3D effects by using a detailed 1D loop simulation to build a data-constrained flare arcade.