N. R. Tanvir
A5048353300- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Particle Detector Development and Performance
- History and Developments in Astronomy
- Microbial Metabolites in Food Biotechnology
- CCD and CMOS Imaging Sensors
- Spectroscopy and Chemometric Analyses
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Cosmology and Gravitation Theories
- Advanced X-ray and CT Imaging
- Isotope Analysis in Ecology
- Neutrino Physics Research
- Planetary Science and Exploration
University of Leicester
2015-2024
Arcetri Astrophysical Observatory
2022
University of Florence
2022
University of Copenhagen
2011-2016
National Astronomical Observatory of Japan
2016
Université Paris Cité
2016
Centre National de la Recherche Scientifique
2016
Sorbonne Paris Cité
2016
Délégation Paris 7
2016
Université Paris Sciences et Lettres
2016
We present a homogeneous X-ray analysis of all 318 gamma-ray bursts detected by the telescope (XRT) on Swift satellite up to 2008 July 23; this represents largest sample GRB data published date. In Sections 2–3, we detail methods which Swift-XRT team has developed produce enhanced positions, light curves, hardness ratios and spectra presented in paper. Software using these continues create such products for new GRBs observed Swift-XRT. also web-based tools allowing users any object XRT, not...
Abstract We report the discovery and monitoring of near-infrared counterpart (AT2017gfo) a binary neutron-star merger event detected as gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) short gamma-ray burst Fermi Gamma-ray Burst Monitor (GBM) Integral SPI-ACS (GRB 170817A). The evolution transient light is consistent with predictions for behavior “kilonova/macronova” powered radioactive decay massive neutron-rich nuclides...
While gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, vast majority MBHs are considered dormant. Occasionally, a star passing too near MBH is torn apart by gravitational forces, leading to bright panchromatic tidal disruption flare (TDF). high-energy transient Swift J164449.3+573451 ("Sw 1644+57") initially displayed none theoretically anticipated (nor previously observed) TDF characteristics, we show that observations (Levan...
We have obtained Johnson V and Gunn i photometry for a large number of Local Group galaxies using the Isaac Newton Telescope Wide Field Camera (INT WFC). The majority these are members M31 subgroup observations deep enough to study top few magnitudes red giant branch in each system. previously measured location tip (TRGB) Andromeda I, II M33 within systematic uncertainties typically <0.05 mag. As TRGB acts as standard candle old, metal-poor stellar populations, we were able derive distances...
The morphological properties of galaxies between $21 {\rm~mag} < I 25 {\rm~mag}$ in the {\em Hubble Deep Field} are investigated using a quantitative classification system based on measurements central concentration and asymmetry galaxian light. class distribution objects is strongly skewed towards highly asymmetric objects, relative to distributions from both HST Medium Survey} at $I 22 an artificially redshifted sample local galaxies. steeply rising number count-magnitude relation for...
Gamma-ray bursts (GRBs) serve as powerful probes of the early Universe, with their luminous afterglows revealing locations and physical properties star forming galaxies at highest redshifts, potentially locating first generation (Population III) stars. Since GRB have intrinsically very simple spectra, they allow robust redshifts from low signal to noise spectroscopy, or photometry. Here we present a photometric redshift z~9.4 for Swift-detected 090429B based on deep observations...
A significant fraction of the Long Gamma-ray Bursts (LGRBs) in Swift sample have a plateau phase showing evidence ongoing energy injection. We suggest that many Short (SGRBs) detected by satellite also show Explaining this observation within typical SGRB progenitor model is challenging as late time accretion, often used to explain plateaus LGRBs, likely be absent from population. Alternatively, it predicted remnant NS-NS mergers may not collapse immediately BH (or even at all), forming...
We report the discovery by Swift hard X-ray monitor of transient source J2058.4+0516 (Sw J2058+05). Our multi-wavelength follow-up campaign uncovered a long-lived (duration ≳ months), luminous (LX, iso ≈ 3 × 1047 erg s−1) and radio (νLν, 1042 counterpart. The associated optical emission, however, from which we measure redshift 1.1853, is relatively faint, this not due to large amount dust extinction in host galaxy. Based on numerous similarities with recently discovered GRB 110328A/Swift...
Variable X-ray and gamma-ray emission is characteristic of the most extreme physical processes in Universe, studying sources these energetic photons has been a major driver astronomy for past 50 years. Here we present multiwavelength observations unique selected transient, discovered by Swift, which was accompanied bright across electromagnetic spectrum, whose properties are unlike any previously observed source. We pinpoint event to center small, star-forming galaxy at redshift z=0.3534....
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
(Abridged). We present a sample of 77 optical afterglows (OAs) Swift detected GRBs for which spectroscopic follow-up observations have been secured. provide linelists and equivalent widths all lines redward Ly-alpha. discuss to what extent the current bursts with OA spectroscopy is biased subsample GRBs. For that purpose we define an X-ray selected optimal conditions ground-based follow up from period March 2005 September 2008; 146 fulfill our criteria. derive redshift distribution this...
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
We present comprehensive multiwavelength observations of three gamma-ray bursts (GRBs) with durations several thousand seconds. demonstrate that these events are extragalactic transients; in particular we resolve the long-standing conundrum distance GRB 101225A (the "Christmas-day burst"), finding it to have a redshift z=0.847, and showing two apparently similar (GRB 111209A 121027A) lie at z=0.677 z=1.773 respectively. The systems show extremely unusual X-ray optical lightcurves, very...
We present an analysis of the large-scale structure halo Andromeda galaxy, based on Pan-Andromeda Archeological Survey (PAndAS), currently most complete map resolved stellar populations in any galactic halo. Despite presence copious substructures, global follow closely power-law profiles that become steeper with increasing metallicity. divide sample into stream-like and a smooth component (defined as population cannot be spatially distinct substructures PAndAS). Fitting three-dimensional...
We present multiwavelength observations of the afterglow GRB 130427A, brightest (in total fluence) gamma-ray burst (GRB) past 29 yr. Optical spectroscopy from Gemini-North reveals redshift to be z = 0.340, indicating that its unprecedented brightness is primarily result relatively close proximity Earth; intrinsic luminosities both and are not extreme in comparison other bright GRBs. a large suite spanning 300 s 130 days after demonstrate shows simple, smooth evolution at all frequencies,...