National Astronomy Meeting Poster Exhibition

The electrons in the solar wind exhibit an interesting kinetic substructure with many important implications for the overall energetics of the plasma in the heliosphere. We are especially interested in the kinetic evolution of the electron strahl, a field-aligned beam of superthermal electrons, in the near-Sun solar wind. We develop a kinetic transport equation for typical heliospheric conditions based on a Parker-spiral geometry of the magnetic field. We present the results of our theoretical model for the radial evolution of the electron velocity distribution function (VDF) in the solar wind. We study the effects of the adiabatic focusing, free streaming due to the electron temperature gradient, wave-particle interactions, and Coulomb collisions through a generalized kinetic equation for the electron VDF. We compare and contrast our results with the observed effects in the electron VDFs from space missions that explore the radial evolution of electrons in the inner heliosphere such as Helios, Parker Solar Probe, and Solar Orbiter.

The solar corona has many unsolved questions and one of the most important is how it is heated. However, the corona also hosts a cooling problem alongside the heating problem. The corona consists of large amounts of cool and dense material called coronal rain. This cool and dense plasma falling from coronal heights.

In this study, we report the SJI/IRIS observations of coronal rain at the East limb of the Sun observed on 2017 July, 2 between 07:28 UT and 12:55 UT in the 1400 Å and 2796 Å passband. We present here a spatial and temporal analysis of coronal rain. To detect coronal rain, we used the Rolling Hough Transforma (RHT) algorithm (Schad 2017). We calculated the amount of rain in both SJI channels. According to the pioneer results, much more rain was observed in SJI 2796 Å observations compared to the SJI 1400 Å.

On the other hand, we analyzed the up-flows and down-flows motion of coronal rain. Downflow motions are more dominant and this is consistent with the literature. We found 59.8 km/s and 49.3 km/s for the projected velocities in SJI 1400 Å and SJI 2796 Å, respectively. We also observed that the number of coronal rain events varies strongly with height and velocity.

Understanding star formation in dwarf galaxies has proven a persistent challenge for galaxy formation numerical simulations. In order for these simulations to produce results that better match observed galaxies, accounting for additional baryonic physics (e.g. stellar radiation, magnetic fields, and cosmic rays) has been frequently advocated. Nonetheless, in their absence, methods such as calibrating stellar feedback have allowed simulations to more effectively reproduce e.g. expected stellar masses. However, doing so has the detrimental effect of disrupting the match attained for other observables.

Investigating our simulations devised to explore the role played by these additional physics, I present here our first results from radiative transfer, cosmic rays, magnetohydrodynamical (RTCRMHD) simulations of a dwarf galaxy formation in a cosmological context. I compare our simulations with observational measures of stellar mass, morphology, kinematics, and metal enrichment. Our suite of simulations provides encouraging prospects suggesting RTCRMHD physics may contribute to overcome various ongoing dwarf galaxy formation problems, and in particular, to resolve or alleviate our necessity for stellar feedback calibration.

In this talk, I will present new results on two-dimensional dual-tree complex wavelet transform (DTCWT) based motion magnification (MM) in the sub-pixel regime.

Motion magnification (MM) is a state-of-the-art method to magnify transverse, quasi-periodic subresolution movements of the contrast features in image sequences. The recently discovered regime of decayless kink oscillation is characterised by the low-amplitude undamped transverse oscillation of inhomogeneities such as coronal loops. Decayless oscillations are ubiquitous in the solar corona, hence a promising routine seismological diagnostics tool. Statistical studies on the decayless kink oscillation show that its averaged amplitude is ~0.17 Mm, which is 0.42 pixel in AIA spatial resolution in the EUV band. The analysis of such small motion therefore relies on MM. In this work, we examine the robustness of DTCWT-based MM in sub-pixel regime through artificial image sequences that imitates persistent kink oscillations of coronal loops with transverse profile of different transverse steepnesses. The algorithm works well on the analysis of sub-pixel oscillation, giving a linear scaling of the magnified amplitudes with the input amplitude when the magnified one is kept above 0.7 pixel. In addition, MM preserves the transverse profiles with different steepnesses. Keeping the transverse profile is important for studying any evolution of the loop, such as broadening from Kelvin-Helmholtz instability, and the consequent effect on the damping rate by resonant absorption. Thus, MM provides us with an effective and robust method for the study of low-amplitude kink oscillations of solar plasma non-uniformities and their application in coronal seismology.

We investigate the effect of magnetic helicity for the stability of buoyant magnetic cavities as found in the intergalactic medium. In these cavities we insert helical magnetic fields and test whether or not helicity can increase their stability to shredding through the Kelvin-Helmholtz instability and with that their life time. This is compared to the case of an external magnetic field which is known to reduce the growth rate of the Kelvin-Helmholtz instability. By comparing a low and high helicity configuration with the same magnetic energy we find that an internal helical magnetic field stabilizes the cavity. This effect increases as we increase the helicity content. Stabilizing the cavity with an external magnetic field requires a significantly stronger field.

The IRAP Plasmasphere Ionosphere Model (IPIM) is an ionospheric model which describes the transport equations of ionospheric plasma species along magnetic closed field lines. As input, the previous iteration of IPIM used basic models to provide estimations of the solar wind conditions, convection, and precipitation within the ionosphere. In this presentation, we discuss the development of a new operational version of IPIM as part of the EUHFORIA project to monitor and forecast space weather conditions and hazards. The developments of the model include using in-situ solar wind observations from the OMNI data set, ionospheric radar data of plasma motions from the Super Dual Auroral Radar Network (SuperDARN), and precipitation data from the Ovation model, as inputs to the model. A new conductivity module for low latitudes has also been developed for help in the simulation of geomagnetically induced currents. We compare the new IPIM version with the previous version and ionospheric observations to explore the differences observed by including these data within the model. We present the first results from this version which explore the ionosphere’s response to different solar wind conditions, including some extreme space weather events such as high-speed streams and coronal mass ejections.

The electromagnetic counterparts (EMC) of gravitational wave (GW) events arising from the coalescence of two merging compact objects, namely a neutron star paired with another neutron star (NSNS)/black-hole (BHNS), have become increasingly topical over the last few years following the GW170817A. In this study, we explore the host environments and offsets of these binaries upon merging. This is accomplished by seeding and dynamically evolving synthetic isolated systems within hydrodynamical galaxies produced by the cosmological simulation, EAGLE. This approach also allows for constraints to be placed on the relative cosmic rate of EM bright binary mergers. Using constraints on the mass ratio of the primary and secondary compact objects, we explore the likelihood of observing potential short-duration gamma-ray bursts (SGRBs) using the Swift/BAT instrument resulting from these systems and compare them to real observations.

Accurate measurements of the dark matter content of a large, diverse sample of galaxies can provide valuable constraints on the cosmological model. IFU surveys observe the stellar kinematics within galaxies, which can be used to build dynamical models and measure the dark matter content in these galaxies. However, stellar kinematics only trace the innermost regions of the dark matter halo, and fail to constrain the halo parameters in the outer regions. Neutral Hydrogen is known to extend beyond the stellar regions in a cold rotating disc. These regions are very dark matter dominated, so can provide strong constraints on the dark matter content.

We have been exploring the potential for methods which can make use of this extra information to improve dynamical models, with the minimum observation required. We have tested a method which combines Jeans modelling with MaNGA IFU observations and the addition of single dish Hydrogen observations from Green Bank Telescope, as part of the HI-MaNGA followup programme. We outline results from testing this method, and future plans to test further improvements with spatially resolved HI data.

We quantify the contributions of different convection states to the magnetic flux throughput of the magnetosphere during 2010. To do this we provide a continuous classification of convection state for the duration of 2010 based upon observations of the solar wind and interplanetary magnetic field, geomagnetic indices, and field-aligned currents measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). Convection states are defined as 1) quiet and 2) weak activity, substorm 3) growth, 4) expansion, and 5) recovery phases, 6) substorm driven phase (when relatively steady magnetospheric convection occurs), 7) recovery bays (when recovery phase is accompanied by a negative excursion of the AL electrojet index), and 8) periods of multiple intensifications (storm-time periods when continuous short-period AL activity occur). The magnetosphere is quiet for 46% of the time, when very little convection takes place. The majority of convection occurs during growth and driven phases (21% and 38%, respectively, of open magnetic flux accumulation by dayside reconnection). We discuss these results in the context of the expanding/contracting polar cap model of convection, and describe a framework within which isolated substorms and disturbances during periods of more continuous solar wind-magnetosphere driving can be understood.

Resolved multi-wavelength and integral-field spectroscopic observations of galaxies allow a reconstruction of when and where within galaxies stars are formed. This can be pursued through a spatially resolved analysis of the fossil record or by observing more direct resolved probes of instantaneous star formation for galaxies across a range of redshifts. In order to obtain a picture of not just the unobscured but the overall star formation activity at all radii it is essential to account for spatial inhomogeneities in the dust distribution. I will report on lessons learned from studying tracers of star formation, dust extinction and dust re-emission on kiloparsec scales within galaxies from the peak epoch of cosmic star formation down to the present day. I will further pay attention to the new windows on resolved star formation that will soon be opened by JWST.