arXiv subjects

S. Pradyumna

Publications and source records attributed to S. Pradyumna.

5 recordsLinked to original sources

arXiv2023

SN 2023ixf in Messier 101: Photo-ionization of Dense, Close-in Circumstellar Material in a Nearby Type II Supernova

We present UV/optical observations and models of supernova (SN) 2023ixf, a type II SN located in Messier 101 at 6.9 Mpc. Early-time ("flash") spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of H I, He I/II, C IV, and N III/IV/V with a narrow core and broad, symmetric wings arising from the photo-ionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for $\sim$8 days with respect to first light, at which time Doppler broadened features from the fastest SN ejecta form, suggesting a reduction in CSM density at $r \gtrsim 10^{15}$ cm. The early-time light curve of SN2023ixf shows peak absolute magnitudes (e.g., $M_{u} = -18.6$ mag, $M_{g} = -18.4$ mag) that are $\gtrsim 2$ mag brighter than typical type II supernovae, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light curve and multi-epoch spectral models from the non-LTE radiative transfer code CMFGEN and the radiation-hydrodynamics code HERACLES suggests dense, solar-metallicity, CSM confined to $r = (0.5-1) \times 10^{15}$ cm and a progenitor mass-loss rate of $\dot{M} = 10^{-2}$ M$_{\odot}$yr$^{-1}$. For the assumed progenitor wind velocity of $v_w = 50$ km s$^{-1}$, this corresponds to enhanced mass-loss (i.e., ``super-wind'' phase) during the last $\sim$3-6 years before explosion.

astro-ph.HE↗

arXiv2022

Characterization of the GRB prompt fundamental plane using Fermi-GBM data

A recent work has found a tight global relation between the GRB prompt fluence, peak flux (based on the optimum time scale determined from the Bayesian Blocks-based analysis) and duration using data from the Fermi Gamma-Ray burst monitor, which they have dubbed as "Fundamental Plane". We quantitatively characterize the tightness of this Fundamental Plane relation by calculating the scatter in dex. We also check for a fundamental plane using the peak flux over time scales of 64 ms, 256 ms and 1024 ms. For our analysis, we incorporate the uncertainties in the above observables and carried out both a PCA as well as regression-based analysis. We find that the scatter in the fundamental plane is 0.16-0.17 dex.

astro-ph.HE↗

arXiv2022

A test of galaxy cluster fundamental plane for the X-COP sample

We test the galaxy cluster fundamental plane using the X-COP sample of 12 clusters. The fundamental plane is given by the relation $T_X \propto M_s^α r_s^β$, where $T_X$, $M_s$, and $r_s$ correspond to the gas temperature, NFW halo mass, and scale radius, respectively. We did this analysis using two different temperatures: the error-weighted temperature in $(50-500)h^{-1}$ kpc as well as the mass-weighted temperature in the same range. With both these temperatures, we find a very tight fundamental plane with dispersion of about 0.02 dex. The best-fit values for $α$ and $β$ are in-between those expected from virial equilibrium and self-similarity solution for secondary infall and collapse, with $α$ being closer to the virial expectation. Our best-fit values are also consistent with a recent re-analyses of the fundamental plane for the CLASH sample, after excluding the hottest clusters.

astro-ph.CO↗

arXiv2021

A test of Radial Acceleration Relation for the {\it Giles et al Chandra} cluster sample

We carry out a test of the radial acceleration relation (RAR) for a sample of 10 dynamically relaxed and cool-core galaxy clusters imaged by the Chandra X-ray telescope, which was studied in Giles et al. For this sample, we observe that the best-fit RAR shows a very tight residual scatter equal to 0.09 dex. We obtain an acceleration scale of $1.59 \times 10^{-9} m/s^2$, which is about an order of magnitude higher than that obtained for galaxies. Furthermore, the best-fit RAR parameters differ from those estimated from some of the previously analyzed cluster samples, which indicates that the acceleration scale found from the RAR could be of an emergent nature, instead of a fundamental universal scale.

astro-ph.CO↗

arXiv2020

Yet another test of Radial Acceleration Relation for galaxy clusters

We carry out a test of the radial acceleration relation (RAR) for galaxy clusters from two different catalogs compiled in literature, as an independent cross-check of two recent analyses, which reached opposite conclusions. The datasets we considered include a Chandra sample of 12 clusters and the X-COP sample of 12 clusters. For both the samples, we find that the residual scatter is small (0.11-0.14 dex), although the best-fit values for the Chandra sample have large error bars. Therefore, we argue that at least one of these cluster samples (X-COP) obeys the radial acceleration relation. However, since the best-fit parameters are discrepant with each other as well as the previous estimates, we argue that the RAR is not universal. For both the catalogs, the acceleration scale, which we obtain is about an order of magnitude larger than that obtained for galaxies, and is agreement with both the recent estimates.

astro-ph.CO↗