Research

(1) Prof. Dr. Binil Aryal (Head)

Research Area:

(a)     Spatial Orientation of Galaxies in the Clusters & Superclusters (one Ph.D. student & 9 masters' thesis students, Collaboration: Austrian Science Fund, Prof. Dr. Walter Saurer): There have been numerous galaxy orientation studies in the past, mostly to the end of verifying various galaxy cluster formation scenarios. The `pancake model' (Doroshkevich 1973) predicts that the rotation axes of galaxies tend to lie within the cluster plane whereas the `primordial vorticity model' (Ozernoy 1978) says that the rotation axes of galaxies tend to be oriented perpendicular to the cluster plane. According to the `hierarchy model' (Peebles 1969) the directions of the rotation axes shouldbe distributed randomly. Authors have drawn different conclusions regarding these scenarios: (1) no preferred alignment (Helou & Salpeter 1982; Bukhari & Cram 2003; Aryal & Saurer 2005c), (2) tend to orient parallel (Jaaniste & Saar 1978; Flin & Godlowski 1986; Godlowski 1993, 1994; Godlowski, Baier & MacGillivray 1998, Flin 2001) or perpendicular (Reinhardt & Roberts 1972; Gregory, Thompson & Tifft 1981; MacGillivray et al. 1982; Baier, Godlowski & MacGillivray 2003) with respect to the cluster (or LSC) plane, (3) bimodal tendency (Kashikawa & Okamura 1992) (3) local anisotropy (Flin 1995, Djorgovski 1983, Aryal & Saurer 2004, 2005a, 2006a,b, 2008, 2010, 2012, 2013, Godlowski et al. 2005, 2010, 2013), (4) global anisotropy (Parnovsky, Karachentsev & Karachentseva 1994), etc. These results suggest different alignments of galaxies in clusters and superclusters. We intend to draw a conclusion regarding the evolution of galaxies in the clusters and superclusters. [19 publications in the peer reviewed Journals: 3 in the process of publication, one recently submitted.

(b)     Interaction in the Interstellar Medium (three Ph.D. students & 8 masters' thesis students, Collaboration: Prof. Dr. Ronald Weinberger, Innsbruck University, Austria European Science Fund): The Infrared Astronomical Satellite (IRAS) mission was a major advance for astronomy. Almost the entire sky was covered in four passbands (12, 25, 60, and 100 $\mu$m). The all-sky maps turned out to be useful in many respects, e.g. by demonstrating that dust structures are ubiquitous and come in all kinds of shapes and sizes. Curiously enough – although the IRAS mission took place two decades ago – the maps are still not exhausted of their riches, as we could demonstrate by e.g. the discovery of jet like structures (size 9 degree) found in the far infrared (Weinberger & Armsdorfer 2004) and a new far infrared nebula (coined as Skeleton nebula by Aryal & Weinberger 2006).  These fossil jets and nebula were discovered as a byproduct during our systematic search for dust structures around PNe: the latter structures around PNe can be ancient and can originate from interactions of the wind of the precursors of PNe, the AGB stars, with ambient (interstellar) matter (ISM). Obviously, high-speed collimated outflows or jets acting during the late AGB or proto planetary nebula (PPN) phase are responsible for the non-sphericity and thus play a decisive role in shaping PNe (Soker 2004; Vinkovic et al. 2004). We study dust structures found in the far IR around the PNe, Red Giant stars, White Dwarfs and Pulsars, on maps of the Infrared Astronomical Satellite (IRAS).  [7 publications in the peer reviewed Journals: 2 in the process of publication.

(c)     Chirality in the Large Scale Structure (two masters' thesis students, Funded by IAU): By considering the group of transformations acting on the configuration space, Capozziello & Lattanzi (2006) claimed that the spiral galaxies exhibit chiral symmetry in the large scale structure. In addition, they predicted that the progressive loss of chirality might have some connection with the rotationally-supported (spirals, barred spirals) and randomized systems (lenticulars, ellipticals). We (Aryal et al. 2007) carried out a study to test Capozziello & Lattanzi's (2006) prediction regarding the progressive loss of chirality in the large scale structure. The existence of chiral symmetry for both the spirals and the barred spirals in the Local Supercluster (LSC) is noticed. However, the Virgo cluster galaxies show a preferred alignment: the galactic rotation axes of leading and trailing structures are found to lie in the equatorial plane. Aryal & Saurer (2005a) noticed a preferred alignment for the late-type spirals and barred spirals in the LSC. In addition, they found that the spin vector (SV) projections of early- and late-type spirals show opposite alignment. Our interest is to study the chiral symmetry and the spatial orientation of the galaxies in and around the Local Supercluster. [3 publications in the peer reviewed Journals: one each in A&A and Ap&SS, 2 in the process of publication.

(2) Prof. Dr. Mukunda Mani Aryal
Research Area: to be added later

(3) Prof. Dr. Uday Raj Khanal
Research Area: to be added later

(4) Prof. Dr. Jeevan Jyoti Nakarmi

(5) Dr. Raju Khanal
Research Area:
I have one project funded by a foreign agency: Our project entitled "Developing Capacity for Nuclear Physics and Nuclear Chemistry Teaching Programmes at Tribhuvan University" is accepted by International Atomic Energy Agency (IAEA), Vienna, Austria for the period 2014-2016 and work is already underway. The total budget approved by IAEA is EURO 141400.- (one lakh forty-one thousand four hundred). The project is aimed at updating/improving the existing teaching programs and methods, especially of nuclear physics and nuclear chemistry. This includes Laboratory setup (repair, maintenance and procurement of equipments dedicated for practicals), training of faculties and staff, scientific visits, etc. I have collaboration with the following foreign groups: (1) Prof. Siegbert Kuhn, Institute for Theoretical Physics, University of Innsbruck, Innsbruck, Austria (2) Prof. Ralf Kaiser, Section Head Physics, IAEA, Vienna, Austria (3) Prof. Arun K. Sarma, VIT University, Chennai Campus Chennai, India (5) Dr. Rinda Hedwig, Bina Nusantara University, Jakarta, Indonesia.

(6) Dr. Narayan Pd Adhikari

Research Area: I basically work in the area of simulation of materials. My primary areas of research interest are as follows.
(a)     Ab initio simulations of solids: We are interested to study the electronic structure of solids using the first-principles calculations. We have been working on the electronic, vibrational and magnetic properties of disordered binary and ternary alloys.  The aim is to study the properties of electrons and phonons in disordered solids, in particular random, substitutional alloys. Further we have been studying the phase stability and phase diagrams of alloy systems.  We use the Augmented Space technique to study the disordered alloys systems. This technique was developed by Prof.  Abhijit Mookerjee who is our collaborator. (Currently, two Ph.D. students are working in this research area. One of them has already submitted his Dissertation.)

(b)     Phase diagram of methane and methane hydrate clathrates: Methane is one of the most important fuel sources. It is extremely important in industry and also it plays very important role in structure of our planets where extreme conditions of low temperature and high pressure are prevalent. In this regard our research interest is to study the phase diagram of methane and clathrate systems like methane-clathrate at the very high pressure and different temperatures.  We study the detailed phase diagram of solid methane and methane hydrate clathrates. (We collaborate with Prof. Sandro Scandolo, ICTP, Trieste, Italy in this research area and currently there is one Ph.D. student).

(c)     Molecular dynamics of simple systems: We are interested in molecular dynamics of simple systems. Molecular dynamics is a computer simulation of physical movements of atoms and molecules in the context of N-body simulation. Computer experiments play a very important role in science today especially in chemical physics, materials science and the modeling of biomolecules. Everything that living things do can be understood in terms of the jigglings and wigglings of atoms. In the most common version, the trajectories of atoms and molecules are determined by numerically solving the Newton's equations of motion for a system of interacting particles, where forces between the particles and potential energy are defined by molecular mechanics force fields.  We use molecular dynamics simulations to study the diffusion of simple molecules like oxygen, nitrogen, CO, inert gases etc. Further we study the phase diagram of some simple systems like methane using this technique.

(d)     Graphene and 2D Novel Materials: Graphene is a two dimensional atomic crystal which consists of carbon atoms arranged in a hexagonal lattice. Since the first experimental observation of this material in 2004, it continues to amaze with its unusual electronic, structural, chemical, optical, mechanical and other properties. Graphene has novel electronic properties that include high electron mobility. The electronic properties of graphene have been of considerable interest because of unique structural and electronic properties of graphene. Defects often affect the mechanical and electronic properties of materials. The study of defects in grapheme is also important as most of the times it plays crucial role in tuning the electronic properties of graphene. Defects, adatoms and geometrical confinement of graphene play important role in tuning the electronic properties of graphene. It is important to clarify the influence of defects on the mechanical and electrical properties of graphene and graphite in order to produce high performance  carbon materials. We basically focus on the effects of defects on the transport properties of graphene like 2D novel materials. (For this we collaborate with Prof. Biplab Sanyal Uppsala University, Uppsala, Sweden).
Collaborators:

1. Prof. Ravindra Pandey, Michigan Technological University, Michigan, USA; 2. Prof. Prem Chapagain, Florida International University, Florida, USA; 3. Prof. Ali Hassanali, The Abdus Salam International Center for Theoretical Physics, Trieste, Italy; 4. Prof. Shobhana Narasimhan, JNCASR, Bangalore, India; 5. Prof. Somen Bhattacharjee, IOP, Bhuvaneshwar, India; 6. Prof. Ramkumar Thapa, Mizoram University, India; 7. Prof. Tribhuvan Pareek, HRI, India.


(7) Dr. Hari Lamichhanne
Research Area: to be added later

(8) Dr. Balram Ghimire
Research Area: to be added later

(9) Dr. Ram Prasad Regmi
Research Area: to be added later

(10) Dr. Sanju Shrestha
Research Area: to be added later