Title : The Highlights Of 55th Lunar And Planetary Science Conference (LPSC-2024)

Abstract

Mr. Trinesh Sana and Dr. Subham Sarkar attended the 55th Lunar and Planetary Science Conference (LPSC-2024) held from 11th to 15th March 2024 at the Woodlands, Houston, Texas, United States of America. This conference brings together international specialists in petrology, geochemistry, geophysics, geology, and astronomy to present the latest research results in planetary science. The conference is organized jointly by the Lunar and Planetary Institute and NASA. The meeting provides a unique opportunity for scientists from around the world to talk about the latest results of their research and current planetary science missions. Trinesh presented his recent work regarding Dust Charging Within Lunar Photoelectron Sheath. Subham delivered a talk about the maiden detection of Natrolite on Mars using Perseverance Rover Data. Apart from presenting in their own sessions, they have attended various other sessions covering topics to their interests. In this seminar, these two young researchers will share their experiences and knowledge gathered from the conference.

Title : New Ways to Detect Light Dark Matter

Abstract

In the last few years, direct detection of light sub-GeV dark matter has emerged as a frontier research area. Because of its low energy scales, many condensed matter systems have been proposed as possible target materials. In this talk, I'll briefly review the mechanisms behind a few of them, and introduce two novel ideas. First, to use superconducting quantum devices to measure the power deposition from dark matter scattering. I'll show that the existing data already put competitive limits on the dark matter-nucleon interaction. I'll also describe how bilayer graphene with voltage-tunable band gap can be used to probe sub-MeV dark matter-electron scattering with promising future prospects.

Title : Dark Matter: the Enigma of our Cosmos

Abstract

We have known about the existence of a dark sector in our Universe for almost 100 years that comprises about 85% of all matter. However, we are still in the dark about its fundamental nature. In this talk, I will describe various evidences of dark matter that we have, and outline a few theoretical ideas to explain its cosmic abundance. Finally, I will give an overview of various experimental endeavors to identify it, such as direct, indirect detection experiments etc.

Title : Daksha: Indian Eyes on Transient Skies

Abstract

Daksha is a proposed High Energy transients mission that will have higher sensitivity than any other mission in the world. Daksha will comprise of two satellites covering the entire sky from 1 keV to > 1 MeV. The primary objectives of the mission are to discover and characterize electromagnetic counterparts to gravitational wave sources; and to study Gamma Ray Bursts (GRBs). With its broadband spectral response, high sensitivity, and continuous all-sky coverage, it will discover fainter and rarer sources than any other existing or proposed mission. Daksha can make key strides in GRB research with polarization studies, prompt soft spectroscopy, and fine time-resolved spectral studies. In addition, Daksha is a versatile all-sky monitor that can address a wide variety of science cases. Daksha will provide continuous monitoring of X-ray pulsars. It will detect magnetar outbursts and high energy counterparts to Fast Radio Bursts. Using Earth occultation to measure source fluxes, the two satellites together will obtain daily flux measurements of bright hard X-ray sources including active galactic nuclei, X-ray binaries, and slow transients like Novae. Correlation studies between the two satellites can be used to probe primordial black holes through lensing. Daksha will have a set of detectors continuously pointing towards the Sun, providing excellent hard X-ray monitoring data. Closer to home, the high sensitivity and time resolution of Daksha can be leveraged for the characterization of Terrestrial Gamma-ray Flashes. In this talk, I will discuss the scientific impact of Daksha in all these areas

Title : Cloud-Cloud Collision: Formation of Hub-Filament Systems and Associated Gas Kinematics

Abstract

Massive star-forming regions (MSFRs) are commonly associated with hub-filament systems (HFSs) and sites of cloud-cloud collision (CCC). Recent observational studies of some MSFRs suggest a possible connection between CCC and the formation of HFSs. To understand this connection, we analyzed the magneto-hydrodynamic simulation data from Inoue et al. (2018). This simulation involves the collision of a spherical molecular cloud with a plane-parallel sea of dense molecular gas at a relative velocity of about 10 km/s. Following the collision, turbulent and non-uniform cloud undergoes shock compression, rapidly developing filamentary structures within the compressed layer. We found that CCC can lead to the formation of HFSs, which is a combined effect of turbulence, shock compression, magnetic fields, and gravity. The collision between the cloud components shapes the filaments into a cone and drives inward flows among them. These inward flows merge at the vertex of the cone, rapidly accumulating high-density gas, which can lead to the formation of massive star(s). The gas distribution in the position-velocity and position-position spaces highlights the challenges in detecting two cloud components and confirming their complementary distribution if the colliding clouds have a large size difference. However, such CCC events can be confirmed by the position-velocity diagrams presenting gas flow toward the vertex of the cone, which hosts gravitationally collapsing high-density objects, and by the magnetic field morphology curved toward the direction of collision. In this talk, I will present these initial results.

Title : Dancing Lunar Dust

Abstract

The Lunar Horizontal Glow, observed during the Surveyors and Apollo missions, unveiled the intricate dynamics of lunar dust movement. The movement of lunar dust, akin to "dancing," is primarily driven by electrostatic forces generated by the continual bombardment of charged particles from the solar wind and highly energetic UV photons on the lunar surface and dust particles. This celestial choreography is important for unravelling the fundamental processes governing surface evolution not only on the Moon but also across other airless bodies throughout the solar system.

Title : Highly Siderophile Elements In Lunar Mantle And Crust Beyond The Procellarum KREEP Terrane

Abstract

Volcanism and collisional impacts are the two primary processes that have shaped the terrestrial bodies of the Solar System. While these geological processes are ubiquitous across planetary bodies, the absence of an atmosphere and minimal active geologic processes (e.g., plate tectonics) on the Moon makes it the prime candidate for understanding these processes over a large timescale (~4.4 – 2.0 Ga). The absolute and relative abundances of the highly siderophile elements (HSE: Re, Os, Ir, Ru, Rh, Pt, Pd, and Au) have long been utilized to understand the volcanic and impact history of the Moon. Most of our current understanding of the abundance of highly siderophile elements (HSE) in the Moon comes from returned samples, which limits our insight. This motivates us to analyze additional samples, particularly those likely sourced away from the Procellarum KREEP Terrane (PKT), to better understand HSE abundance and Re-Os isotope variability in lunar crust and mantle reservoirs. In this talk, I will discuss the HSE and Re-Os isotopic abundance of four lunar meteorites, A-881757, Y-86032, Y 981031, and Y 983885, that are likely sourced away from the PKT region. The unbrecciated lunar meteorite A-881757 provides a key understanding of the HSE abundance in the KREEP-free lunar mantle, while the regolith breccia meteorites Y-86032, Y 981031, and Y 983885 offer us to examine the nature, flux, and composition of the materials striking the unexplored lunar surface away from the PKT. Most importantly, these results will provide a robust constraint on the HSE abundance of the Moon, globally.

Title : Let’s slip into inspiral

Abstract

I will start with a brief introduction to gravitational waves and update about the current detections and my involvement in those. My main focus will be a state-of-the-art discussion on contemporary tests of general relativity with gravitational wave observations and my contributions to developing a few of those.

Title : Optical Monitoring of a long-period dynamically new comet C/2020 V2 (ZTF)

Abstract

Comets are the pristine bodies that retain the essential information of the early Solar System. They are mainly placed in two reservoirs, i.e., Kuiper Belt and Oort Cloud. These reservoirs hold a large number of comets. The comets in the Kuiper belt are responsible for the short-period low-inclination known as Jupiter family comets (JFC), while comets in the Oort Cloud account for the long-period comets with different inclinations (as compared to the JFC). Studying the composition of different classes of comets is essential to understanding the formation and evolution of the Solar System. Dynamically New Comet (DNC) is a subcategory of long-period comets with a semi-major axis > 10000 AU. These comets are entering the inner Solar System for the first time, which gives us an excellent opportunity to study their composition. The Zwicky Transient Facility discovered Comet C/2020 V2 (ZTF) in November 2020. It was categorized as a dynamically new comet. In the talk, I will present the different results of this dynamically new comet C/2020 V2 (ZTF) using the photometric observations from TRAPPIST and spectroscopic observations from different observatories in India.

Title : Gaining insight into radiative and variability phenomena of black hole X-ray binaries

Abstract

Around 72 Black Hole X-ray Binary (BHXB) candidates have been discovered till now, showcasing variety of radiative phenomena and rapid variability in the X-ray lightcurve. This variability manifests itself as Quasi-Periodic Oscillations (QPOs) and broadband noise continuum in the power spectra. These properties offer a unique lens to study extreme gravitational environments in close regions to the black hole. Despite substantial research, our understanding of the origin and energy-dependent behaviour of the variability remains incomplete. I will focus on the modelling of variability, testing its different origins and exploring the spectral behaviour in different accretion regimes, using data from AstroSat, NICER, NuSTAR and Swift. In addition, I will discuss a peculiar case of a highly luminous BHXB, which exhibited non-standard disk behaviour. I will conclude by exploring future prospects to better our understanding of the accretion physics around different compact object systems.