About Me

Hi! I'm a neutrino astrophysicist by profession, currently working with the IceCube experiment at Uppsala University. I graduated in Applied Physics from IIT (ISM) Dhanbad, India in 2015, and obtained my PhD in 2020 from the University of Pisa in Italy. My PhD dissertation dealt with identifying blazar candidates that could likely be neutrino emitters, by studying their gamma-ray activity, with the broader aim to constrain their observability by km³ Cherenkov telescopes like IceCube and KM3NeT. In my short career so far, I've participated in the KM3NeT experiment over the course of my PhD, besides also working briefly for the ANTARES neutrino observatory as an undergrad. I have experience/expertise in data analysis, calibration and multi-messenger astronomy.

When I'm not working, I enjoy watching football, and playing chess and table tennis. I'm very fond of the night sky and it's beauty, and whenever I can grab hold of a telescope, I like to go stargazing under dark skies! After graduating, I spent one year as an astronomy Educator, promoting amateur astronomy and science among students and public. I've also done some volunteer work while at the University, relating to education of underprivileged children and upliftment of marginalised communities. I'm currently a member of the Sweden Chapter of Engineers Without Borders (EWB - Sweden).

Research

My research revolves around investigating the most extreme phenomena in the Universe, those accelerating cosmic rays to the highest observed energies (E > 10²⁰ eV). These can occur in the kpc scale jets emitted by supermassive black holes located at the centers of some galaxies, called AGN. Some of these AGNs have their jets pointing right in the direction of the Earth, and these AGNs are termed 'blazars'. Blazars are theoretically capable of accelerating particles to energies of PeV-EeV and above. But the large distances at which these blazars are located, make it very difficult to study them using just EM radiation. Deflection of charged cosmic rays in the Galactic and extra-galactic magnetic fields is another hindrance.

Neutrinos are charge-neutral and weakly-interacting particles produced alongside the high-energy gamma-rays when accelerated cosmic ray particles interact with the ambient gas or radiation. They can reach the Earth unabsorbed and undeflected from their source. This makes them the ideal messenger to investigate the physics of jet production and acceleration in AGNs. But these properties also make it difficult to detect them on Earth with our conventional detectors. An additional problem is imposed by the irreducible background of atmospheric neutrinos produced by cosmic rays impinging on the Earth's atmosphere. Neutrino experiments avoid this problem by building detectors deep below ground level in a transparent medium to suppress the atmospheric muon flux and looking for particles that arrive at the detector after crossing the Earth, since only neutrinos can travel through a substantial portion of Earth without getting absorbed.

The currently operational neutrino observatories are IceCube, located at the South Pole, and ANTARES, located at the bottom of the Mediterranean Sea. The upcoming ones include KM3NeT, the successor to ANTARES, and Baikal-GVD, under construction in Lake Baikal, Russia. These Gigaton detectors, covering instrumented volumes of upto a cubic km, rely on the Cherenkov light produced by the muons/electrons when a neutrino interacts in the vicinity of the detector. This light is detected by the sensitive PMTs and used to reconstruct the direction and energy of the interacting particle and in turn, the parent neutrino.

Research Interests

Phenomenological studies of VHE emission from jets of AGNs; multi-messenger and multi-wavelength connection in blazars with neutrino, gamma-ray and X-ray data; gamma-ray astronomy; observability of point sources with Cherenkov neutrino telescopes; detection strategies for ultra-high energy neutrinos

Current Project

      A model-independent analysis of neutrino flares detected in IceCube from X-ray selected blazars

Blazars are among the most powerful steady sources in the Universe. Multi-messenger searches from blazars have traditionally focused on their gamma-ray emission, which can be produced simultaneously with neutrinos in photohadronic interactions. However, X-ray data can be equally vital to constrain the SED of these sources, since the hadronically co-produced gamma-rays can get absorbed by the ambient photon fields and cascade down to X-ray energies before escaping.

I plan to perform an untriggered, time-dependent search for neutrino flares from the direction of X-ray selected blazars using 10 years of IceCube data. A binomial test on the population will be used to reveal if a subcategory of sources has statistically significant emission. The source catalog under consideration is RomaBZCat, and p-values and flare parameters are obtained for each source using an unbinned likelihood maximization.

IceCube Neutrino Observatory

The IceCube Neutrino Observatory is the first detector of its kind, designed to observe the cosmos from deep within the South Pole ice. An international group of scientists responsible for the scientific research makes up the IceCube Collaboration.

Encompassing a cubic kilometer of ice, IceCube searches for nearly massless subatomic particles called neutrinos. These high-energy astronomical messengers provide information to probe the most violent astrophysical sources: events like exploding stars, gamma-ray bursts, and cataclysmic phenomena involving black holes and neutron stars.

The Antarctic neutrino observatory, which also includes the surface array IceTop and the dense infill array DeepCore, was designed as a multipurpose experiment. IceCube collaborators address several big questions in physics, like the nature of dark matter and the properties of the neutrino itself. IceCube also observes cosmic rays that interact with the Earth’s atmosphere, which have revealed fascinating structures that are not presently understood.