A5023188523- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- SAS software applications and methods
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Neutrino Physics Research
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- Particle Detector Development and Performance
- Nuclear Issues and Defense
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Planetary Science and Exploration
- Cancer Research and Treatments
- Mitochondrial Function and Pathology
- Nuclear Physics and Applications
- Fluorine in Organic Chemistry
- Numerical methods in inverse problems
- Gas Dynamics and Kinetic Theory
- Space Science and Extraterrestrial Life
Manipal Academy of Higher Education
2024
Inter-University Centre for Astronomy and Astrophysics
2018-2022
Stockholm University
2015-2020
AlbaNova
2015-2020
Aryabhatta Research Institute of Observational Sciences
2010-2014
University of Liège
2014
We present light curves and spectra of the tidal disruption event (TDE) ASASSN-18pg / AT 2018dyb spanning a period one year. The shows plethora strong emission lines, including Balmer series, He II, I metal lines O III $\lambda$3760 N $\lambda\lambda$ 4100, 4640 (blended with II). latter are consistent originating from Bowen fluorescence mechanism. By analyzing literature past events, we conclude that these common in TDEs. spectral diversity optical TDEs is thus larger than previously...
We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time H-alpha emission with line luminosities (1-3)e+41 erg/s velocity widths (4000-6000) km/s. Including the previously published iPTF13ehe, this makes up a total three such events to date. iPTF13ehe is one most luminous slowest evolving SLSNe-I, whereas other are less fast decliners. interpret as result ejecta running into neutral H-shell located at radius ~ 1.0e+16cm....
At 66 Mpc, AT2019qiz is the closest optical tidal disruption event (TDE) to date, with a luminosity intermediate between bulk of population and iPTF16fnl. Its proximity allowed very early detection triggering multiwavelength spectroscopic follow-up well before maximum light. The velocity dispersion host galaxy fits TDE light curve indicate black hole mass $\approx 10^6$ M$_\odot$, disrupting star 1$ M$_\odot$. Comprehensive UV, X-ray data shows that emission dominated by an outflow,...
We report on the discovery and observations of extremely luminous optical transient CSS100217:102913+404220 (CSS100217 hereafter). Spectroscopic show this was coincident with a galaxy at redshift z=0.147, reached an apparent magnitude V ~ 16.3. After correcting for foreground Galactic extinction we determine absolute to be M_V =-22.7 approximately 45 days after maximum light. Based our unfiltered photometry peak emission L = 1.3 x 10^45 erg s^-1, over period 287 rest-frame had integrated...
We present densely sampled UBVRI/griz photometric and low-resolution (6–10 Å) optical spectroscopic observations from 4 to 270 d after explosion of a newly discovered Type II SN 2012aw in nearby (∼9.9 Mpc) galaxy M95. The light-curve characteristics apparent magnitudes, colours, bolometric luminosity the presence evolution prominent spectral features are found have striking similarity with archetypal IIP SNe 1999em, 1999gi 2004et. early time clearly detect minima light curve V, R I bands...
In this paper we report a new transiting warm giant planet: KOI-1257 b. It was first detected in photometry as planet-candidate by the ${\it Kepler}$ space telescope and then validated thanks to radial velocity follow-up with SOPHIE spectrograph. orbits its host star period of 86.647661 d $\pm$ 3 s high eccentricity 0.772 0.045. The planet transits main metal-rich, relatively old binary system stars mass 0.99 0.05 Msun 0.70 $ \pm 0.07 for primary secondary, respectively. This is constrained...
ABSTRACT We present the results of a large multiwavelength follow-up campaign tidal disruption event (TDE) AT 2019dsg, focusing on low to high resolution optical spectroscopy, X-ray, and radio observations. The galaxy hosts super massive black hole mass $\rm (5.4\pm 3.2)\times 10^6\, M_\odot$ careful analysis finds no evidence for presence an active galactic nucleus, instead TDE host shows narrow emission lines that likely arise from star formation activity. transient is luminous in X-rays,...
We present the low-resolution spectroscopic and UBVRI broad-band photometric investigations of Type IIb supernova 2011fu, discovered in UGC 01626.The follow-up this event has been initiated a few days after explosion covers period about 175 days.The early-phase light curve shows rise followed by steep decay all bands shares properties very similar to that seen case SN 1993J, with possible detection adiabatic cooling phase.Modelling quasi-bolometric suggests progenitor had an extended (∼ 1 ×...
Context. Some circumstellar-interacting (CSI) supernovae (SNe) are produced by the explosions of massive stars that have lost mass shortly before SN explosion. There is evidence precursors some SNe IIn were luminous blue variable (LBV) stars. For a small number CSI SNe, outbursts been observed Eruptive events named as impostors (SN IMs) and whether they herald forthcoming or not still unclear. The large variety observational properties suggests existence other progenitors, such red...
A Type IIn supernova (SN) is dominated by the interaction of SN ejecta with circumstellar medium (CSM). Some SNe (e.g., 2006jd) have episodes re-brightening ("bumps") in their light curves. We present iPTF13z, a discovered intermediate Palomar Transient Factory (iPTF) and characterised several bumps its curve. analyse this peculiar behaviour trying to infer properties CSM explosion, as well nature progenitor star. obtained multi-band optical photometry for over 1000 days after discovery P48...
ABSTRACT In the present paper we report discovery of a new hot Jupiter, K2-29 b, first detected by Super-WASP observatory and then K2 space mission during its campaign 4. The planet has period 3.25 days, mass 0.73 ± 0.04 M ♃ , radius 1.19 0.02 R . host star is relatively bright ( V = 12.5) G7 dwarf with nearby K5V companion. Based on stellar rotation abundance lithium, find that system might be as young ~450 Myr. observation Rossiter–McLaughlin effect shows aligned respect to spin. Given...
We present optical photometric and low-resolution spectroscopic observations of the Type II plateau supernova (SN) 2008in, which occurred in outskirts nearly face-on spiral galaxy M 61. Photometric data X-rays, ultraviolet near-infrared bands have been used to characterize this event. The SN field was imaged with ROTSE-IIIb telescope about seven days before explosion. This allowed us constrain epoch shock breakout JD = 2454825.6. duration phase, as derived from monitoring, ~ 98 days. spectra...
Super-luminous supernovae (SLSNe) are rare events defined as being significantly more luminous than normal terminal stellar explosions. The source of the extra powering needed to achieve such luminosities is still unclear. Discoveries in local Universe (i.e. $z<0.1$) scarce, but afford dense multi-wavelength observations. Additional low-redshift objects therefore extremely valuable. We present early-time observations type I SLSN ASASSN-18km/SN~2018bsz. These data used characterise event and...
We present a spectroscopic analysis of Type I superluminous supernova (SLSN-I), SN 2018bsz. While it closely resembles SLSNe-I, the multi-component H$\alpha$ line appearing at $\sim30$ d post-maximum is most atypical. The characterised by two emission components, one $+3000$ km/s and second $-7500$ km/s, with third, near-zero velocity component after delay. blue central components can be described Gaussian profiles intermediate width, but red significantly broader Lorentzian. evolves towards...
We present SN2018kzr, the fastest declining supernova-like transient, second only to kilonova, AT2017gfo. SN2018kzr is characterized by a peak magnitude of $M_r = -17.98$, bolometric luminosity ${\sim} 1.4 \times 10^{43}$erg s$^{\mathrm{-1}}$ and rapid decline rate $0.48 \pm 0.03$ mag day$^{\textrm{-1}}$ in $r$ band. The evolves too quickly be explained pure $^{\mathrm{56}}$Ni heating, necessitating inclusion an alternative powering source. Incorporating spin-down magnetized neutron star...
Context: Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by $\sim2$ mag) than canonical core-collapse SNe (CCSNe). These with visual peak magnitudes $\lesssim-21$ called superluminous (SLSNe). Aims: There few intermediate have luminosities between these two classes. Here we study one such object, SN 2012aa. Methods: The optical photometric and spectroscopic follow-up observations event were conducted time...
We present nearly 500 days of observations the tidal disruption event ASASSN-18pg, spanning from 54 before peak light to 441 after light. Our dataset includes X-ray, UV, and optical photometry, spectroscopy, radio observations, first published spectropolarimetric a TDE. ASASSN-18pg was discovered on 2018 July 11 by All-Sky Automated Survey for Supernovae (ASAS-SN) at distance $d=78.6$ Mpc, with UV magnitude $m\simeq14$ it is both one nearest brightest TDEs to-date. The photometric data allow...
We present and discuss the results of an extensive observational campaign devoted to GRB071010A, a long-duration gamma-ray burst detected by Swift satellite. This event was followed for almost month in optical/near-infrared (NIR) with various telescopes starting from about 2min after high-energy event. Swift-XRT observations started only later at 0.4d. The light-curve evolution allows us single out initial rising phase maximum 7min, possibly afterglow onset context standard fireball model,...
The supernovae of Type Ibc are rare and the detailed characteristics these explosions have been studied only for a few events. Unlike II SNe, progenitors never detected in pre-explosion images. So, to understand nature their explosions, investigation proximate events necessary. Here we present results multi-wavelength observations Ib SN 2007uy nearby ($\sim$ 29.5 Mpc) galaxy NGC 2770. Analysis photometric revealed this explosion as an energetic event with peak absolute R band magnitude...
We present results from a systematic selection of tidal disruption events (TDEs) in wide-area (4800 deg2), g + R band, Intermediate Palomar Transient Factory (iPTF) experiment. Our targets typical optically-selected TDEs: bright (>60% flux increase) and blue transients residing the center red galaxies. Using photometric criteria to down-select total 493 nuclear sample 26 sources, we then use follow-up UV imaging with Neil Gehrels Swift Telescope, ground-based optical spectroscopy, light...
Massive stars, possibly red supergiants, which retain extended hydrogen envelopes until core collapse, produce Type II Plateau (IIP) supernovae. The ejecta from these explosions shock the circumstellar matter originating mass loss of progenitor during final phases its life. This interaction accelerates particles to relativistic energies then lose energy via synchrotron radiation in shock-amplified magnetic fields and inverse Compton scattering against optical photons supernova. These...
We present the radio observations and modeling of an optically bright Type II-P supernova (SN), SN 2012aw which exploded in nearby galaxy Messier 95 (M95) at a distance 10 Mpc. The spectral index values calculated using C, X, K bands are smaller than expected for thin regime. During this time, optical bolometric light curve stays plateau phase. interpret low spectral-index to be result electron cooling. On basis comparison between Compton cooling timescale synchrotron timescale, we find that...
In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range linear sizes (220 $-$ 917 kpc), hence time scales episodic activity. Here present high-sensitivity 607-MHz Giant Metrewave Radio Telescope (GMRT) images 21 double-double (DDRGs) from FIRST survey confirm their nature. These GMRT observations show that none inner compact components suspected be hot-spots doubles...