A5047757685- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Photocathodes and Microchannel Plates
- Atmospheric Ozone and Climate
- Scientific Research and Discoveries
- Radio Astronomy Observations and Technology
- Calibration and Measurement Techniques
- Astro and Planetary Science
Inter-University Centre for Astronomy and Astrophysics
2022-2024
Indian Institute of Astrophysics
2016-2021
Pondicherry University
2019-2021
National Research Council Canada
2016
Indian Space Research Organisation
2016
Tata Institute of Fundamental Research
2016
Indian Institute of Science Education and Research Kolkata
2016
National Centre for Radio Astrophysics
2016
Abstract The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, first Indian Space Observatory. UVIT instrument has two 375 mm telescopes: for far-ultraviolet (FUV) channel (1300–1800 Å), and other near-ultraviolet (NUV) (2000–3000 Å) visible (VIS) (3200–5500 Å). primarily designed simultaneous imaging ultraviolet channels with spatial resolution better than 1.″8, along provisions slit-less spectroscopy NUV FUV channels. results in-orbit calibrations are presented this paper.
Abstract We report the direct detection of Lyman continuum (LyC) emission from nine galaxies and one active galactic nucleus at z ∼ 1.1–1.6 in GOODS-North field using deep observations Ultraviolet Imaging Telescope (UVIT) on board AstroSat. The absolute escape fraction sources estimated far-ultraviolet H α -line luminosities Monte Carlo analysis two intergalactic medium models span a range ∼10%–55%. rest-frame UV wavelength falls extreme-ultraviolet regime ∼550–700 Å, shortest LyC probed so...
ABSTRACT We characterize the evolution of rest-frame 1500 Å UV luminosity function (UVLF) from AstroSat/UVIT F154W and N242W imaging in Great Observatories Origins Survey North (GOODS-N) field. With deep FUV observations, we construct UVLF for galaxies at z$\lt 0.13$ subsequently it with a Schechter fit. The fitted parameters are consistent previous determinations. NUV able to seven redshift bins range z$\sim$0.4–0.8, identified till $\sim$2 mag fainter than surveys, owing high...
ABSTRACT We present early results from the Ultra-Violet Imaging Telescope (UVIT) on board ASTROSAT observatory. report discovery of a hot companion associated with one blue straggler stars (BSSs) in old open cluster, NGC 188. Using fluxes measured four filters UVIT’s far-UV (FUV) channel, and two near-UV (NUV) we have constructed spectral energy distribution (SED) star WOCS-5885, after combining flux measurements GALEX , Ultraviolet Telescope, Optical SPITZER WISE several ground-based...
Abstract We present deep UV imaging observations of the Great Observatories Origins Survey Northern (GOODS-N) field with AstroSat/UVIT (AstroSat Deep Field north—AUDFn), using one far-UV (FUV) (F154W, 34.0 ks) and two near-UV (NUV) filters (N242W, 19.2 ks; N245M, 15.5 ks). The nature sky background was explored across UVIT field, a global mean rms were estimated for each filter. reach 3 σ detection limits m AB ∼ 27.35, 27.28, 27.02 mag point source in F154W, N242W, N245M bands respectively....
The physical processes related to the effect of bars in quenching star formation region between nuclear/central sub-kiloparsec and ends bar (bar region) spiral galaxies is not fully understood. It hypothesized that can either stabilize gas against collapse, inhibiting formation, or efficiently consume all available gas, leaving no fuel for further formation. We present a multiwavelength study using archival data an early-type barred galaxy, Messier 95, which shows signatures suppressed...
We present the discovery of a peculiar central stellar structure in collisional ring galaxy AM0644-741 using HST imaging and MUSE integral field unit (IFU) data. identified two S'ersic components with index 1.72 (inner part) 1.11 (outer F814W band optical image Galfit . utilized data cube to construct line-of-sight velocity (V_ LOS), dispersion (σ_ h_3 h_4 moments, population age maps GIST pipeline for further investigating both components, which have difference ∼ 60 degrees their position...
Abstract We estimate the UV continuum slope ( β ) of 465 galaxies (with luminosities 0.028–3.3 <?CDATA ${L}_{z=0.5}^{* }$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.5</mml:mn> <mml:mo>*</mml:mo> </mml:msubsup> </mml:math> in Great Observatories Origins Survey Northern field redshift range z = 0.40–0.75. use two AstroSat/UVIT (N242W, N245M) bands, Hubble...
We have used the Ultraviolet Imaging Telescope (UVIT) aboard AstroSat to study star formation in a sample of nine dual nuclei galaxies with separations ~11 kpc, which is an expected outcome galaxy mergers. To minimize contribution active galactic (AGN) emission, we mid-IR color cut-offs and masked AGN-dominated nuclei. The UV continuum slope ($\beta$) calculate internal extinction (A$_V$) ranges from 0.53 4.04 FUV band 0.44 3.10 NUV for sample. detected $1-20$ star-forming clumps (SFCs) our...
Abstract We present the AstroSat UV Deep Field south (AUDFs), an imaging survey using wide-field Ultraviolet Imaging Telescope on board AstroSat. AUDFs cover ∼236 arcmin 2 of sky area, including Great Observatories Origins Survey (GOODS) South field in F154W and N242W filters. The deep shallow parts have exposure time ∼62,000 ∼31,000 s, respectively, filter, while they are ∼64,000 ∼34,000 s. These observations reached a 3 σ depth 27.2 27.7 AB mag with 50% completeness limit 27 27.6 filters,...
We present a study of star forming regions and its demographics in the nearby dwarf irregular galaxy WLM using Ultra-Violet Imaging Telescope (UVIT) multi band observations three filters F148W, N245M N263M. find that UV emission is extended at least up to 1.7 kpc, with NUV more than FUV. create color maps ((F148W$-$N245M) (F148W$-$N263M)) temperature morphology young stellar complexes help theoretical models. identify several T $>$ 17500 K which are likely be OB associations galaxy. These...
Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into red-sequence galaxy, though details still unclear. Here we explore pattern of recent star formation in central region galaxy NGC7252 using high resolution UV images from UVIT on ASTROSAT. The with 1.2 1.4 arcsec FUV NUV used construct FUV-NUV colour map region. pixel for this canonical reveals blue circumnuclear ring diameter $\sim$ 10 " (3.2 kpc) bluer patches located...
Abstract Star formation in galaxies is a hierarchical process with wide range of scales, from smaller clusters to larger stellar complexes. Here, we present an ultra-violet imaging study the nearby flocculent spiral galaxy NGC 7793, observed using Ultra-Violet Imaging Telescope (UVIT). We find that disk scale length estimated Far-UV (2.64 ± 0.16 kpc) than Near-UV (2.21 0.21 Kpc) and optical (1.08 Kpc), which supports inside-out growth scenario disk. The star-forming UV also found be...
$\require{mediawiki-texvc}$ Supermassive black holes at the centre of active galactic nuclei (AGN) produce relativistic jets that can affect star formation characteristics AGN hosts. Observations in ultraviolet (UV) band provide an excellent view effect on formation. Here, we present a census properties Northern Star-forming Region (NSR) spans about 20 kpc large radio source Centaurus A hosted by giant elliptical galaxy NGC 5128. In this region, identified 352 UV sources associated with Cen...
Abstract The relation between the observed UV continuum slope ( β ) and infrared excess (IRX) is used as a powerful probe to understand nature of dust attenuation law in high-redshift galaxies. We present study 83 UV-selected galaxies redshift 0.5 0.7 from AstroSat Deep Field north that encloses GOODS-North field. Using empirical relation, we estimate IRX 52 are detected either one or both Herschel PACS 100 160 μ m bands. further utilize multiband photometric data 14–18 filters Ultra-Violet...
Abstract We present results from simultaneous far-ultraviolet (FUV) and near-ultraviolet (NUV) observations of T Tauri stars (TTSs) in the Taurus molecular cloud with UVIT/AstroSat. This is very first UVIT study TTSs. From spectral energy distribution TTSs FUV to IR, we show that classical (CTTSs) emit significantly higher UV excess compared weak-line (WTTSs). The equivalent blackbody temperatures corresponding CTTSs (>10 4 K) are also found be relatively than those WTTSs (<9250 K)....
Star forming dwarf galaxies in the local volume are diverse and ideal test beds to understand details of star formation a variety environments. Here, we present deep FUV imaging study nearby irregular galaxy IC 2574 using Ultraviolet Imaging Telescope (UVIT). We identified 419 bright regions with radii between 15 - 285 pc found that 28.6\% them be located H~I shells, 12.6\% inside holes 60.1\% away from holes. The column density is more than $10^{21} cm^{-2}$ for 82.3\% regions. 30 out 48...
According to the Λ cold dark matter model of galaxy formation, hierarchical assembly process is scale-free and interactions between galaxies in all mass ranges are expected. The effects dwarf on their evolution not well understood. In this study, we aim understand effect low-mass star formation rate (SFR). We estimated SFR 22 interacting 36 single gas-rich Lynx-Cancer void region using far-ultraviolet (FUV) images from GALEX mission. find an enhancement by a factor 3.4 ± 1.2 for systems...
The underlying nature of the process star formation quenching in central regions barred disc galaxies that is due to action stellar bar not fully understood. We present a multi-wavelength study four using archival data from optical, ultraviolet, infrared, CO, and HI imaging on progression gas distribution better understand quenching. found for three galaxies, region between nuclear or sub-kiloparsec end (bar region) devoid neutral molecular hydrogen. While detected hydrogen very negligible,...
We present early results from the Ultra-Violet Imaging Telescope (UVIT) onboard ASTROSAT observatory. report discovery of a hot companion associated with one blue straggler stars (BSSs) in old open cluster, NGC188. Using fluxes measured four filters UVIT's Far-UV (FUV) channel, and two near-UV (NUV) we have constructed spectral energy distribution (SED) star WOCS-5885, after combining flux measurements GALEX, UIT, UVOT, SPITZER, WISE several ground-based facilities. The resulting SED spans...
Molecular clouds fragment under the action of supersonic turbulence & gravity which results in a scale-free hierarchical distribution star formation (SF) within galaxies. Recent studies suggest that SF nearby galaxies shows dependence on host galaxy properties. In this context, we study nature from few tens pc up to several kpc 4 spiral NGC1566, NGC5194, NGC5457 NGC7793, by leveraging large FoV high resolution FUV+NUV observations UltraViolet Imaging Telescope (UVIT). Using two-point...
abstract Molecular clouds fragment under the action of supersonic turbulence and gravity, which results in a scale-free hierarchical distribution star formation within galaxies. Recent studies suggest that nearby galaxies shows dependence on host galaxy properties. In this context, we study from few tens parsecs up to several kiloparsecs four spiral galaxies: NGC 1566, 5194, 5457, 7793, by leveraging large-field-of-view high-resolution far-ultraviolet (FUV) near-ultraviolet (NUV)...
We report the direct detection of Lyman Continuum (LyC) emission from 9 galaxies and 1 Active Galactic Nuclei (AGN) at $z$ $\sim$ 1.1-1.6 in GOODS-North field using deep observations Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. The absolute escape fraction sources estimated far-ultraviolet (FUV) H$\alpha$ line luminosities Monte Carlo (MC) analysis two Inter-Galactic Medium (IGM) models span a range 10 - 55 $\%$. restframe UV wavelength falls extreme-ultraviolet (EUV) regime...