Siddhartha Gupta

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Hi! I am a Postdoctoral Scholar in the Department of Astronomy and Astrophysics at the University of Chicago, Illinois in USA. Before joining here, I received PhD from the Indian Institute of Science and Raman Research Institute, Bengaluru in India, under the Joint Astronomy Programme.

I am a theoretical astrophysicist working on fluid and plasma problems related to shocks, cosmic rays, and stellar feedback. My present research focuses on cosmic-ray-driven plasma instabilities, and fluid modelling of cosmic rays. I use simulations (Hydro and Particle-In-Cell) and analytic method to study these problems.

Research highlights

From where ?

I am from Burdwan (Bardhaman), a town located on the shore of Damodar river in a district Burdwan in West Bengal, India.

CMS high school
Municipal high school
Raj College
Indian Institute of Technology Kharagpur
Indian Institute of Science Bangalore
Raman Research Institute

Academic Journey

School Days : My academic carrier was started from the National School. I did the primary education (class I to IV) at Burdwan Church Missionary Society (CMS) High school. After that, I moved to Burdwan Municipal High school (BMHS) to complete higher secondary.
College Days : From my school days, I like Physical science and Mathematics. I started my carrier in Physics at Burdwan Raj College (BRC) which runs under the University of Burdwan (BU). I completed the Bachelor of Science (BSc) Physics honors in year 2012 with a first rank in BU.
IIT days : Pursuing Master of Science (MSc) in the dept of Physics at Indian Institute of Technology Kharagpur (IIT Kgp) was the most important time in my academic carrier. During a one-year long project with Sayan Kar, I decided to take theoretical astrophysics as a broad area of research. I completed MSc in 2014 with a first rank in the physics dept, and left IIT kgp to explore my area of interest.
PhD days : I completed graduation in 2019 from Indian Institute of Science (IISc), Bengaluru, India. I was enrolled under the Joint Astronomy Programme (JAP) as a Shyama Prasad Mukherjee (SPM) senior research fellow. As the programme name suggests, the JAP allows to work in multiple institutes. I jointly worked with Biman Nath at Raman Research Institute (RRI) and Prateek Sharma at Indian Institute of Science Bengaluru (IISc), India.
Present position : I have recently joined the University of Chicago, USA as a Postdoctoral Scholar in the Dept of Astronomy and Astrophysics (UChicago) to work with Damiano Caprioli.

To know about my research interests visit Research.

Non-Academic Journey!

In free times, I like playing guitar, singing (youtube), and drawing. A few selected drawings are attached below.


  • Fluid and Plasma
  • Cosmic rays
  • Numerical methods
  • Gravity


Damiano Caprioli (Postdoc advisor), University of Chicago, IL, USA.
David Eichler, Ben-Gurion University, Israel.
Colby Haggerty, University of Chicago, IL, USA.
Andrea Mignone, University of Torino, Italy.
Biman Nath (PhD advisor), Raman Research Insitute Bangalore, India.
Prateek Sharma (PhD advisor), Indian Institute of Science Bangalore, India.
Yuri Shchekinov, Lebedev Physical Institute Moscow, Russia.

Research summary

To know our contributions, click on the tabs below.
Movie 1: Effects of stellar radiation + wind + SNe in ISM. The top panel shows the mechanical power (green) and radiation bolometric luminosity (violet). The pointers indicate the instantaneous power at that epoch. The bottom two panels show temperature (red) and density (blue) profiles of an interstellar bubble. The bottom-right panel displays the zoomed-in view of the swept-up ISM (also known as shell) in the shock frame. The effect of first supernova, radiation heating and formation of the neutral shell are clearly seen from this movie.

Star clusters are one of the most energetic sources in a galaxy. They emit wind and radiation which are so energetic that they can expel gas from their vicinity. Observers have found such gas expulsion, however, the driving mechanism was not clear.

We have studied this problem by considering the time evolution of a star cluster. We use a realistic Initial Mass Function (IMF) and include stellar winds (source of mechanical energy) and radiation in our analysis. After ~3 Myr when one-by-one massive stars die through supernova explosion, they also provide mechanical energy. However, the radiation power decreases with time. Therefore, the contribution from wind and radiation depend on the age of the star cluster. Using 1D numerical simulations, we show that radiation pressure can push the gas before 1 Myr. After 1 Myr, the expansion is controlled by mechanical power and radiation heating. Movie 1, shown here, displays the time evolution of various profiles due to interactions of stellar wind and radiation with the ambient medium.

Gupta et al. (2016) MNRAS, 462, 4532; [NASA/ADS]; MNRAS; arXiv

Movie 2: The time evolution of thermal (red) and CR (blue) pressure profiles in an interstellar bubble. The dotted-red curve shows thermal pressure profile for one-fluid (i.e. cosmic rays) bubble.

Winds and supernovae drive shocks and produce all necessary conditions to accelerate high energy particles (e.g. Cosmic rays (CRs)). Despite the observations over a century, there are many aspects of CRs that are still unknown, e.g. from where do they come from? are they accelerated in supernova shocks or in stellar winds? To understand this problem, we have developed an analytical model and performed 1D and 3D simulations. We have calculated various observables which will be useful to understand high energy activity in star clusters.

Paper I: We develop a two-fluid model of an interstellar bubble (ISB) where cosmic rays are considered as the second fluid. We show that diffusive shock acceleration can be an effective process in changing the thermal properties of an ISB. Movie 2 shows the time evolution of thermal and CR pressure profiles in a two-fluid interstellar bubble. The enhancement of CR pressure at the reverse shock (wind termination shock) represents the diffusive shock acceleration. Once the CR pressure becomes larger than thermal pressure, the shock becomes very smooth representing the globally smooth solution of the two-fluid model. This simulation is performed using a code which is written by me. Details of the code can be found here.

Paper II: In continuation with Paper I, we estimate gamma-ray, x-ray, and radio (thermal and nonthermal) luminosities and compare them with observations. In this study, we show how a compact star cluster can produce diffuse gamma-ray. We also discuss the role of thermal and non-thermal radio, and X-rays in constraining the high energy activity in young star clusters. Movie 3 displays the surface brightness map of an ISB in multi-waveband.
Movie 3: Surface brightness map of an ISB in different waveband. The colour palettes are shown in right side of respective panels. For details, see Gupta, Nath & Sharma (2018)

1. Gupta et al. (2018) MNRAS, 473, 1537; [NASA/ADS]; MNRAS; arXiv
2. Gupta et al (2018) MNRAS 479, 5220; [NASA/ADS]; MNRAS; arXiv

Description to be added.
1. Gupta et al (2020) MNRAS 493, 3159; [NASA/ADS]; MNRAS; arXiv

Description to be added.
1. Gupta et al (2020); [NASA/ADS]; MNRAS; arXiv

My MSc thesis was focused on the applications of a modified Newtonian gravity in various astrophysical objects. This study involved a phenomenological approach which combines strong field and weak field gravities. With my advisor, Prof. Sayan Kar at IIT Kgp, we investigated the non-singular collapse of gas cloud and galaxy rotation curve.
1. Gupta, S. 2014, MScThesis, IIT Kharagpur.

Selected talks/posters

1. 26th June 2018 at the "4th CRISM" conference in Grenoble, France (slides)
2. 13th June 2018 at the "Bubble Big and small" conference at IISc, Bangalore, India (slides)

1. 9-13th May 2016 at the annual Meeting of Astronomical Society of India at Srinagar. ClickHereToSee


Google scholar

1. What happens when a young star cluster interacts with the interstellar medium. For youtube link: click here

[Left] Density slice at z = 0; [Right] Projected map; [Bottom] Input power.
[Left] Wind/SN/ambient tracer slice at z = 0; [Right] Projected map; [Bottom] Input power.

I use the following codes to study astrophysical problems.

Magneto-hydrodynamic simulations

Kinetic simulations

Analysis codes


C header files

It is always good to have your own header files.


ERC 505
Department of Astronomy & Astrophysics
The University of Chicago
5640 S Ellis Avenue, Chicago, IL 60637, United States
Email :

Google scholar