Aravind P. Ravi
A5031565841- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
The University of Texas at Arlington
2020-2024
University of California, Davis
2024
Indian Institute of Science Education and Research Kolkata
2017-2018
International Centre for Theoretical Sciences
2017
Tata Institute of Fundamental Research
2017
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match 2020pni 2017ahn spectrum 2014G at later epochs. To physically...
Abstract We present the densely sampled early light curve of Type II supernova (SN) 2023ixf, first observed within hours explosion in nearby Pinwheel Galaxy (Messier 101; 6.7 Mpc). Comparing these data to recently updated models shock-cooling emission, we find that progenitor likely had a radius 410 ± 10 R ⊙ . Our estimate is model dependent but consistent with red supergiant. These provide good fit starting about 1 day after explosion, despite fact classification spectrum shows signatures...
Abstract We present initial results from a James Webb Space Telescope (JWST) survey of the youngest Galactic core-collapse supernova remnant, Cassiopeia A (Cas A), made up NIRCam and MIRI imaging mosaics that map emission main shell, interior, surrounding circumstellar/interstellar material (CSM/ISM). also four exploratory positions Medium Resolution Spectrograph integral field unit spectroscopy sample ejecta, CSM, associated dust representative shocked unshocked regions. Surprising...
Abstract We present high-cadence photometric and spectroscopic observations of supernova (SN) 2024ggi, a Type II SN with flash spectroscopy features, which exploded in the nearby galaxy NGC 3621 at ∼7 Mpc. The light-curve evolution over first 30 hr can be fit by two power-law indices break after 22 hr, rising from M V ≈ −12.95 mag +0.66 day to −17.91 7 days. In addition, densely sampled color curve shows strong blueward few days then behaves as normal redward ejecta cool. Such deviations...
Abstract Based on our Chandra imaging-spectroscopic observations, we present the latest evolution of X-ray remnant SN 1987A. Recent changes in electron temperatures and volume emission measures suggest that blast wave 1987A is moving out dense inner ring structure, also called equatorial (ER). The 0.5–2.0 keV light curve shows a linearly declining trend (by ∼4.5% yr −1 ) between 2016 2020 as heats hitherto unknown circumstellar medium (CSM) outside ER. While peak 0.3–8.0 image still within...
We present initial results from a JWST survey of the youngest Galactic core-collapse supernova remnant Cassiopeia A (Cas A), made up NIRCam and MIRI imaging mosaics that map emission main shell, interior, surrounding circumstellar/interstellar material (CSM/ISM). also four exploratory positions MIRI/MRS IFU spectroscopy sample ejecta, CSM, associated dust representative shocked unshocked regions. Surprising discoveries include: 1) web-like network ejecta filaments resolved to 0.01 pc scales...
We present a detailed study of SN 2024ahr, hydrogen-poor superluminous supernova (SLSN-I), for which we determine redshift $z=0.0861$. 2024ahr has peak absolute magnitude $M_g\approx M_r\approx -21$ mag, rest-frame rise and decline times (50$\%$ peak) about 40 80 days, respectively, typical spectroscopic evolution in the optical band. Similarly, modeling UV/optical light curves with magnetar spin-down engine leads to parameters: an initial spin period $\approx 3.3$ ms, magnetic field...
Abstract We present a comprehensive multi-epoch photometric and spectroscopic study of SN 2024bch, nearby (19.9 Mpc) Type II supernova (SN) with prominent early high-ionization emission lines. Optical spectra from 2.8 days after the estimated explosion reveal narrow lines H i , He ii C iv N that disappear by day 6. High-cadence photometry ground Transiting Exoplanet Survey Satellite show brightened quickly reached peak M V ~ −17.8 mag within week explosion, late-time suggests 56 Ni mass...
Abstract We present supernova (SN) 2023ufx, a unique Type IIP SN with the shortest known plateau duration ( t PT ∼ 47 days), luminous V -band peak M = −18.42 ± 0.08 mag), and rapid early decline rate s 1 3.47 0.09 mag (50 days) −1 ). By comparing observed photometry to hydrodynamic MESA+STELLA model grid, we constrain progenitor be massive red supergiant ZAMS 19–25 ⊙ . Independent comparisons nebular spectral models also suggest an initial He-core mass of ∼6 , thus progenitor. For IIP,...
Abstract SN 2023ixf was discovered in M101 within a day of the explosion and rapidly classified as Type II supernova with flash features. Here we present ultraviolet (UV) spectra obtained Hubble Space Telescope 14, 19, 24, 66 days after explosion. Interaction between ejecta circumstellar material (CSM) is seen UV throughout our observations flux first three epochs asymmetric Mg ii emission on 66. We compare to CMFGEN models that include CSM interaction ( <mml:math...
Abstract JWST Near Infrared Camera (NIRCam) observations at 1.5–4.5 μ m have provided broadband and narrowband imaging of the evolving remnant SN 1987A with unparalleled sensitivity spatial resolution. Comparing previous marginally spatially resolved Spitzer Array (IRAC) from 2004 to 2019 confirms that emission arises circumstellar equatorial ring (ER), current brightness 3.6 4.5 was accurately predicted by extrapolation declining tracked IRAC. Despite regular light curve, NIRCam clearly...
ABSTRACT JWST/NIRCam obtained high angular resolution (0.05–0.1 arcsec), deep near-infrared 1–5 $\mu$m imaging of Supernova (SN) 1987A taken 35 yr after the explosion. In NIRCam images, we identify: (1) faint H2 crescents, which are emissions located between ejecta and equatorial ring, (2) a bar, is substructure ejecta, (3) bright 3–5 continuum emission exterior to ring. The remnant in 1–2.3 images mostly due line emission, emitted hotspots within contrast, dominated by emission. dust,...
Abstract Based on observations with the Chandra X-ray Observatory, we present latest spectral evolution of remnant SN 1987A (SNR 1987A). We a high-resolution spectroscopic analysis using our new deep (∼312 ks) HETG observation taken in 2018 March as well archival grating data 2004, 2007, and 2011 similarly exposures (∼170–350 ks). perform detailed model fits to quantify changing plasma conditions over last 14 yr. Recent changes electron temperatures volume-emission measures suggest that...
Abstract We present JWST NIRCam (F356W and F444W filters) MIRI (F770W) images NIRSpec Integral Field Unit (IFU) spectroscopy of the young Galactic supernova remnant Cassiopeia A (Cas A) to probe physical conditions for molecular CO formation destruction in ejecta. obtained data as part a survey Cas A. The map spatial distributions synchrotron radiation, Ar-rich ejecta, on both large small scales, revealing remarkably complex structures. emission is stronger at outer layers than Ar which...
Abstract We present photometric and spectroscopic observations of SN 2023fyq, a Type Ibn supernova (SN) in the nearby galaxy NGC 4388 ( D ≃ 18 Mpc). In addition, we trace 3 yr long precursor emission at position 2023fyq using data from DLT40, ATLAS, Zwicky Transient Facility, ASAS-SN, Swift, amateur astronomer Koichi Itagaki. The double-peaked postexplosion light curve reaches luminosity ∼10 43 erg s −1 . strong intermediate-width He lines observed nebular spectrum imply interaction is still...
Abstract We present an analysis of the dispersed spectral data from 11 epochs (2011 March–2018 September) supernova remnant (SNR) 1987A observations performed with Chandra. These were High Energy Transmission Grating (HETG) as part our ongoing Chandra monitoring campaign SNR 1987A, whose first-order spectrum provides a significantly greater energy resolution than previously published zeroth-order spectrum. Our sets moderate exposure times ∼50–70 ks per epoch cover time period between deep...
We present the optical spectroscopic evolution of SN~2023ixf seen in sub-night cadence spectra from 1.18 to 14 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match SN~2020pni SN~2017ahn spectrum SN~2014G at later epochs. To physically...
Supernova remnants (SNRs) are well-recognised dust producers, but their net production rate remains elusive due to uncertainties in grain properties that propagate into observed mass uncertainties, and determine how efficiently these grains processed by reverse shocks. In this paper, we present a detection of polarised emission the Crab pulsar wind nebula, second SNR with confirmed after Cassiopeia A. We constrain bulk composition new SOFIA/HAWC+ polarimetric data band C 89 um D 154 um....
Abstract We present Spitzer, Wide-field Infrared Survey Explorer (WISE), and Herschel observations of the young supernova remnant (SNR) N132D in Large Magellanic Cloud, including 3–40 μ m Spitzer Spectrograph (IRS) mapping, 12 WISE 70, 100, 160, 250, 350, 500 images. The high-velocity lines [Ne ii ] at 12.8 m, iii 15.5 [O iv 26 reveal infrared ejecta concentrated a central ring coincide with optical X-ray ejecta. images far-IR emission coinciding ejecta, which suggests that IR is freshly...
We present near-infrared (NIR) and optical observations of the Type Ic supernova (SN Ic) SN 2021krf obtained between days 13 259 at several ground-based telescopes. The NIR spectrum day 68 exhibits a rising $K$-band continuum flux density longward $\sim$ 2.0 $\mu$m, late-time shows strong [O I] 6300 6364 \r{A} emission-line asymmetry, both indicating presence dust, likely formed in ejecta. estimate carbon-grain dust mass 2 $\times$ 10$^{-5}$ M$_{\odot}$ temperature 900 - 1200 K associated...
Abstract We present far-infrared (FIR) spectroscopy of supernova remnants (SNRs) based on the archival data Infrared Space Observatory taken with Long Wavelength Spectrometer (LWS). Our sample includes previously unpublished profiles line and continuum spectra for 20 SNRs in Galaxy Magellanic Clouds. In several including G21.5–0.9, G29.7–0.3, Crab Nebula, G320.4–1.2, we find evidence broad [O i ], iii [N ii [C ] lines velocity dispersions up to a few 10 3 km s −1 , indicating that they are...
Based on our Chandra imaging-spectroscopic observations, we present the latest evolution of X-ray remnant SN 1987A. Recent changes in electron temperatures and volume emission measures suggest that blast wave 1987A is moving out dense inner ring structure, also called equatorial (ER). The 0.5-2.0 keV light curve shows a linearly declining trend (by $\sim$4.5 % yr$^{-1}$) between 2016 2020, as heats hitherto unknown circumstellar medium (CSM) outside ER. While peak 0.3-8.0 image still within...
We present photometric and spectroscopic observations of SN 2023fyq, a type Ibn supernova in the nearby galaxy NGC 4388 (D$\simeq$18~Mpc). In addition, we trace long-standing precursor emission at position 2023fyq using data from DLT40, ATLAS, ZTF, ASAS-SN, Swift, amateur astronomer Koichi Itagaki. Precursor activity is observed up to nearly three years before explosion, with relatively rapid rise final 100 days. The double-peaked post-explosion light curve reaches luminosity...
We present a comprehensive multi-epoch photometric and spectroscopic study of SN 2024bch, nearby (19.9 Mpc) Type II supernova (SN) with prominent early high ionization emission lines. Optical spectra from 2.9 days after the estimated explosion reveal narrow lines H I, He II, C IV, N IV that disappear by day 6. High cadence photometry ground TESS show brightened quickly reached peak M$_V \sim$ $-$17.8 mag within week explosion, late-time suggests $^{56}$Ni mass 0.050 M$_{\odot}$....
We present high-cadence photometric and spectroscopic observations of supernova (SN) 2024ggi, a Type II SN with flash spectroscopy features which exploded in the nearby galaxy NGC 3621 at $\sim$7 Mpc. The light-curve evolution over first 30 hours can be fit by two power law indices break after 22 hours, rising from $M_V \approx -12.95$ mag +0.66 days to -17.91$ 7 days. In addition, densely sampled color curve shows strong blueward few then behaves as normal redward ejecta cool. Such...