Astrophysics Core Members
Syed Ashraf Uddin
CASSASupernova Cosmology
Type Ia Supernovae (SNe Ia) are standardizable candles that are extensively used to measure the cosmic expansion history. SNe Ia helped in measuring the expansion rate of the Universe, known as the Hubble-Lemaitre constant (𝐻0), to 1% precision. SNe Ia also led to the surprising discovery of cosmic acceleration, for which an unknown force, termed dark energy, is believed to be responsible. The nature of dark energy is highly debatable from recent analysis. At the same time the value of 𝐻0 is in tension due to a 5 −𝜎 mismatch of its measurements from early and late time Universe. We are undertaking a number of studies to address the issues involving 𝐻0 and dark energy.
- Studying cosmic acceleration and Hubble tension through astrophysical systematics (suitable for postbac or MSc students):
- Effect of Host Galaxy Age on the Luminosity of Type Ia Supernovae.
- Effect of Local Environment on the Luminosity of Type Ia Supernovae.
- Comparing SN Ia luminosity calibration across various light-curve fitters.
- Improving SN Ia standard candles through analysing spectra of their hosts.
- Building a pipeline for spectral analysis of SNe Ia.
Transient Astronomy
Transient events showcase a variety of astrophysical events, such as, supernova, gamma-ray bursts etc. They fall within time-domain astronomy with characteristic timescales between milliseconds to days. The Legacy Survey of Space and Time (LSST) will be discovering millions of transients every night. While follow-up of these transients is a challenging task, worldwide coordinated efforts are going on. In Bangladesh, we aim to initiate such transient follow-up facilities in order to characterize and discover previously unknown transients. Below are some projects related to this area.
- Designing a multiband filter optimized for supernova follow-up (postbac or MSc students).
- Designing a TOM toolkit for the 0.5-m telescope (upon agreement by the Rajshahi Novotheatre).
- Robotosizing the 0.5-m telescope for remote operation (upon agreement by the Rajshahi Novotheatre).
- Observing transients with the Unistellar telescopes of Durbin (citizen science).
Khan Muhammad Bin Asad
CASSACHronOS: Cosmic Hydrogen Observation and Simulation
Neutral hydrogen is the most abundant atom in the universe, and its 21-cm hyperfine emission line is one of the most powerful tools we have for reading cosmic history. From the Dark Ages — when hydrogen filled the intergalactic medium in near-total silence — through the Epoch of Reionization, when the first stars and galaxies ionized the surrounding gas, to the present-day cosmic web, this single spectral line encodes the thermal, ionization, and density history of the universe across billions of years. Mapping it at different redshifts is an attempt to reconstruct how the universe transitioned from a dark, neutral state to the luminous, structured cosmos we inhabit today.
The challenge is that the 21-cm signal is extraordinarily faint — buried orders of magnitude beneath Galactic foregrounds, instrumental noise, and systematic effects that can easily overwhelm any genuine cosmological signature. CHronOS addresses this through simulation: using tools such as 21cmFAST to generate physically realistic models of the hydrogen signal, then constructing simulated observations for LOFAR, SKA-Low, and HERA to identify, characterize, and mitigate these systematics. The central question is not just what the universe looks like in 21-cm light, but whether we can see it clearly at all.
Students joining CHronOS develop skills in cosmological simulation, synthetic observation generation, and systematic effect mitigation — the computational toolkit that will determine how much science SKA-Low can actually deliver. This work sits at a critical juncture: the telescopes are being built, but their scientific return depends on whether the methods are ready. Beyond the technical training, students engage with one of the deepest questions in modern astrophysics — tracing the history of hydrogen from the first moments of cosmic structure to the large-scale universe we observe today.
Knowledgebase: https://cassa.site/abekta/areas/chronos/
GATE: Galaxies And Their Environments
Galaxy clusters are the largest gravitationally bound structures in the universe, and powerful laboratories for studying how environment shapes galaxy evolution. Permeating these structures is the intracluster medium — hot, X-ray-emitting plasma that fills the cluster volume and is not a passive backdrop but an active participant in cluster physics. Radio-loud AGN drive jets that inflate cavities, generate shocks, and deposit enormous energy into this gas; but the ICM is also stirred by cluster mergers and shaped by infalling groups, filaments, and structures extending into the broader cosmic web. How these processes interact to regulate the evolution of galaxies and clusters together is one of the central open problems in extragalactic astronomy.
GATE pursues this through two connected threads. The first focuses on radio AGN — their morphologies, jet structures, haloes, and population properties — using machine learning to extract physical insight from the large, complex datasets of modern radio surveys. The second examines cluster structures in radio and X-ray: cavities, shocks, cold fronts, and diffuse emission that record the combined history of AGN feedback, merger activity, and environmental influence on the ICM. The two threads converge naturally, since understanding the ICM requires reading evidence across wavelengths, scales, and physical processes simultaneously.
Students joining GATE work at the intersection of radio and X-ray astronomy, applying machine learning and multiwavelength analysis to data from LOFAR, VLA, Chandra, and XMM-Newton. Next-generation surveys such as EMU and LoTSS are producing radio AGN catalogs at unprecedented scale, making data-driven approaches increasingly essential. Students develop skills in radio and X-ray analysis, source characterization, and applied machine learning — engaging along the way with some of the most energetic phenomena in the observable universe.
Knowledgebase: https://cassa.site/abekta/areas/gate/
MATRiX: Multiwavelength Astronomy Techniques: Radio and X-ray
Radio interferometry achieves angular resolutions no single dish could match by combining signals from antennas separated by kilometers — but the path from raw visibilities to a science-ready image is long and unforgiving. Every step, from primary beam characterization and calibration to imaging and source extraction, introduces systematic errors that must be understood and controlled. MATRIX develops and refines these pipelines, working within frameworks such as CARACal to build robust, reproducible workflows that can reliably recover faint astrophysical signals from complex interferometric data from telescopes such as MeerKAT, VLA, and LOFAR.
X-ray astronomy opens a complementary window onto the high-energy universe. Chandra reveals the hot diffuse gas in galaxy clusters, AGN radiation, and merger shock structures — phenomena invisible at other wavelengths. But Chandra data reduction requires careful handling of detector characteristics, background modeling, point source removal, and spectral extraction before any science can be extracted. MATRIX is building a dedicated reduction pipeline for galaxy cluster observations, creating a reproducible framework that takes raw event files through to calibrated, analysis-ready data products.
Students in MATRIX work directly with the craft of data reduction at both wavelengths. In radio, this means hands-on work with primary beam modeling, calibration, and imaging pipelines. In X-ray, it means contributing to a Chandra cluster pipeline that feeds directly into the science programs of GATE and CHronOS. Students leave with practical expertise in two of the most technically demanding domains in observational astronomy — skills that are in high demand across the field.
Knowledgebase: https://cassa.site/abekta/areas/matrix/