Publications (28)
The Galactic Faraday rotation sky 2020
Sebastian Hutschenreuter, Craig S. Anderson, Sarah Betti +34
This work gives an update to existing reconstructions of the Galactic Faraday rotation sky by processing almost all Faraday rotation data sets available at the end of the year 2020…
Explosive and radio-selected Transients: Transient Astronomy with SKA and its Precursors
Poonam Chandra, G. C. Anupama, K. G. Arun +7
With the high sensitivity and wide-field coverage of the Square Kilometre Array (SKA), large samples of explosive transients are expected to be discovered. Radio wavelengths, espec…
Magnetic Fields, Star Formation Rates and Gas Densities at Sub-kpc Scales in a Pilot Sample of Nearby Galaxies
Souvik Manna, Subhashis Roy
We have estimated the magnetic field strengths of a sample of seven galaxies using their non-thermal synchrotron radio emission at metre wavelengths, and assuming energy equipartit…
Low radio frequency observations of seven nearby galaxies with GMRT
Subhashis Roy, Souvik Manna
We have observed seven nearby large angular sized galaxies at 0.33 GHz using GMRT with angular resolution of and sub-mJy sensitivity. Using archival higher frequency dat…
Radio Observation of Venus at Meter Wavelengths using the GMRT
Nithin Mohan, Subhashis Roy, Govind Swarup +4
The Venusian surface has been studied by measuring radar reflections and thermal radio emission over a wide spectral region of several centimeters to meter wavelengths from the Ear…
Equipartition magnetic fields and star formation rates in normal galaxies at sub-kpc scales
Aritra Basu, Subhashis Roy
We studied the total magnetic field strength in normal star-forming galaxies estimated using energy equipartition assumption. Using the well known radio--far infrared correlation w…
GMRT observations of four suspected supernova remnants near the Galactic Centre
Subhashis Roy, A. Pramesh Rao
We have observed two fields - Field-I (l=3.2 degrees, b=-1.0 degree) and Field-II (l=356.8 degrees, b=-0.1 degree) with the Giant Metrewave Radio Telescope (GMRT) at 330 MHz. In th…
Distance to the Galactic centre 7 halo from HI absorption
Debangan Maji, Subhashis Roy
Using archival data, we have made an HI absorption study of the 7 halo surrounding the Sgr A complex, observed towards the Galactic centre (GC) region. We find strong HI a…
A Bursting Radio Transient in the Direction of the Galactic Center
Paul S. Ray, Scott D. Hyman, T. Joseph Lazio +4
The radio sky is poorly sampled for rapidly varying transients because of the narrow field-of-view of most imaging radio telescopes at cm and shorter wavelengths. The emergence of…
Radio Continuum Halos of 7 Nearby Large Galaxies using uGMRT
Souvik Manna, Subhashis Roy, Tapas Baug
We present the results of deep radio observations of 7 nearby large galaxies observed using the upgraded Giant Metrewave Radio Telescope (uGMRT) 0.3-0.5 GHz receivers with an angul…
Discovery of a small diameter young supernova remnant G354.4+0.0
Subhashis Roy, Sabyasachi Pal
We report discovery of a shell like structure G354.4+0.0 of size 1.6' that shows morphology of a shell supernova remnant. Part of the structure show polarized emission in NRAO VLA…
uGMRT observation of the unidentified PeVatron candidate LHAASO J2108+5157
Gunindra Krishna Mahanta, Subhashis Roy, Sagar Godambe +3
Recent observations by the Large High Altitude Air Shower Observatory (LHAASO) detected Ultra High Energy (UHE) photons in the range 100 TeV to 1.4 PeV from twelve sources includin…
Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz
Yogesh Maan, M. A. Krishnakumar, Arun K. Naidu +4
Although originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131 has exhibited intriguing detections at decameter wavelengths. We report an extensive follow-up of the p…
325 and 610 MHz Radio Counterparts of SNR G353.60.7 a.k.a. HESS J1731347
A. J. Nayana, Poonam Chandra, Subhashis Roy +6
HESS J1731347 a.k.a. SNR G353.60.7 is one of the five known shell-type supernova remnants (SNRs) emitting in the very high energy (VHE, Energy 0.1 TeV) -ray domain. W…
Probing magnetic fields with Square Kilometre array and its precursors
Subhashis Roy, Sharanya Sur, Kandaswamy Subramanian +3
Origin of magnetic fields, its structure and effects on dynamical processes in stars to galaxies are not well understood. Lack of a direct probe has hampered its study. The first p…
Magnetic fields in nearby normal galaxies: Energy equipartition
Aritra Basu, Subhashis Roy
We present maps of total magnetic field using 'equipartition' assumptions for five nearby normal galaxies at sub-kpc spatial resolution. The mean magnetic field is found to be ~11…
Magnetic field near the central region of the Galaxy: Rotation measure of extragalactic sources
Subhashis Roy, A. Pramesh Rao, Ravi Subrahmanyan
To determine the properties of the Faraday screen and the magnetic field near the central region of the Galaxy, we measured the Faraday rotation measure (RM) towards 60 background…
Sgr A* at low radio frequencies: GMRT observations
Subhashis Roy, A. Pramesh Rao
The central region of the Galaxy has been observed at 580, 620 and 1010 MHz with the Giant Metrewave Radio Telescope (GMRT). We detect emission from Sgr-A*, the compact object at t…
The Galactic Centre region
Subhashis Roy
We have observed the central 45' region of the Galaxy at 620 MHz band of the Giant Metrewave Radio Telescope (GMRT) in radio continuum, and measured the polarisation properties of…
Exploring neutral hydrogen in the radio MOlecular Hydrogen Emission Galaxies (MOHEGs) and prospects with the SKA
Sai Wagh, Mamta Pandey-Pommier, Nirupam Roy +6
The empirical studies of cold gas content serve as an essential aspect in comprehending the star formation activities and evolution in galaxies. However, it is not straightforward…
Constraints on distances to Galactic Centre non-thermal filaments from HI absorption
Subhashis Roy
We have studied HI absorption towards three non-thermal filaments (NTFs) Sgr-C, G359.54+0.18 and G359.79+0.17 using the Giant Metrewave Radio Telescope (GMRT). Our study, for the f…
Circularly polarized emission from the transient bursting radio source GCRT J1745-3009
Subhashis Roy, Scott D. Hyman, Sabyasachi Pal +3
We report detection of strong circularly polarized emission from the transient bursting source GCRT J1745-3009 based on new analysis of 325 MHz GMRT observations conducted on 28 Se…
Extragalactic sources towards the central region of the Galaxy
Subhashis Roy, A. Pramesh Rao, Ravi Subrahmanyan
We have observed a sample of 64 small diameter sources towards the central -6 degree < l< 6 degree, -2 degree < b < 2 degree of the Galaxy with the aim of studying the Faraday rota…
Synchrotron spectral index and interstellar medium densities of star-forming galaxies
Aritra Basu, Rainer Beck, Philip Schmidt +1
The spectral index of synchrotron emission is an important parameter in understanding the properties of cosmic ray electrons (CREs) and the interstellar medium (ISM). We determine…
Low frequency radio-FIR correlation in normal galaxies at ~1 kpc scales
Aritra Basu, Subhashis Roy, Dipanjan Mitra
We study the radio--FIR correlation between the nonthermal (synchrotron) radio continuum emission at λ90 cm (333 MHz) and the far infrared emission due to cool (~20 K) dust at λ7…
A New Radio Detection of the Bursting Source GCRT J1745-3009
Scott D. Hyman, T. Joseph W. Lazio, Subhashis Roy +2
GCRT J1745-3009 is a transient bursting radio source located in the direction of the Galactic center, discovered in 330 MHz VLA observations from 2002 September 30--October 1 by Hy…
A Faint, Steep Spectum Burst from the Radio Transient GCRT J1745-3009
Scott D. Hyman, Subhashis Roy, Sabyasachi Pal +4
GCRT J1745-3009 is a transient bursting radio source located in the direction of the Galactic center. It was discovered in a 330 MHz VLA observation from 2002 September 30--October…
Density of warm ionized gas near the Galactic Center: Low radio frequency observations
Subhashis Roy
We have observed the Galactic Center (GC) region at 0.154 and 0.255 GHz with the GMRT. A total of 62 compact likely extragalactic sources are detected. Their scattering sizes go do…