Ashish Kumar Meena
A5048700326- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- History and Developments in Astronomy
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Scientific Research and Discoveries
- Heat Transfer Mechanisms
- GaN-based semiconductor devices and materials
- Optical Polarization and Ellipsometry
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Optical Coatings and Gratings
- Dark Matter and Cosmic Phenomena
- Advanced Optical Sensing Technologies
- Leaf Properties and Growth Measurement
Ben-Gurion University of the Negev
2022-2025
ARC Centre of Excellence for All-sky Astrophysics
2023
ASTRO-3D
2023
Indian Institute of Technology Jammu
2023
University of Zurich
2023
Indian Institute of Science Education and Research Mohali
2019-2022
We give an overview and describe the rationale, methods, first results from NIRCam images of JWST "Prime Extragalactic Areas for Reionization Lensing Science" ("PEARLS") project. PEARLS uses up to eight filters survey several prime extragalactic areas: two fields at North Ecliptic Pole (NEP); seven gravitationally lensing clusters; high redshift proto-clusters; iconic backlit VV 191 galaxy system map its dust attenuation. also includes NIRISS spectra one NEP NIRSpec high-redshift quasars....
Abstract A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; 0.35). The SN is situated 1.5–2 kpc from host-galaxy nucleus and appears three different locations as a result gravitational lensing by G165. These data can yield value for Hubble’s constant using time delays this multiply imaged that we call “SN H0pe.” Over cluster, identified 21 image multiplicities, confirmed five them...
Abstract The first James Webb Space Telescope (JWST) Near InfraRed Camera imaging in the field of galaxy cluster PLCK G165.7+67.0 ( z = 0.35) uncovered a Type Ia supernova (SN Ia) at 1.78, called “SN H0pe.” Three different images this one SN were detected as result strong gravitational lensing, each traversing path spacetime, thereby inducing relative delay arrival image. Follow-up JWST observations all three enabled photometric and rare spectroscopic measurements two time delays. Following...
With increasing sensitivities of the current ground-based gravitational-wave (GW) detectors, prospects detecting a strongly lensed GW signal are going to be high in coming years. When such passes through an intervening lensing galaxy or cluster, embedded stellar-mass microlenses lead interference patterns that may leave observable signatures. In this work, we present extensive study these wave effects LIGO/Virgo frequency band ($10$-$10^4$ Hz) due presence microlens population galaxy-scale...
Abstract The first deep field images from the James Webb Space Telescope (JWST) of galaxy cluster SMACS J0723.3-7327 reveal a wealth new lensed at uncharted infrared wavelengths, with unprecedented depth and resolution. Here we securely identify 14 sets multiply imaged galaxies totaling 42 images, adding to five bright already known Hubble data. We find examples arcs crossing critical curves, allowing detailed community follow-up, such as JWST spectroscopy for precise redshift...
MACS0647$-$JD is a triply-lensed $z\sim11$ galaxy originally discovered with the Hubble Space Telescope. Here we report new JWST imaging, which clearly resolves as having two components that are either merging galaxies or stellar complexes within single galaxy. Both very small, masses $\sim10^8\,M_\odot$ and radii $r<100\,\rm pc$. The brighter larger component "A" intrinsically blue ($\beta\sim-2.6$), likely due to recent star formation no dust, spatially extended an effective radius...
We report the discovery of two extremely magnified lensed star candidates behind galaxy cluster MACS J0647.7+7015, in recent multi-band James Webb Space Telescope (JWST) NIRCam observations. The are seen a previously known, $z_{phot}\simeq4.8$ dropout giant arc that straddles critical curve. lie near expected curve position but lack clear counter images on other side it, suggesting these possibly stars undergoing caustic crossings. present revised lensing models for cluster, including...
The first James Webb Space Telescope (JWST) data on the massive colliding cluster El Gordo allow for 23 known families of multiply lensed images to be confirmed and eight new members these identified. Based families, which have been spectroscopically by MUSE, we derived an initial lens model. This model guided identification 37 additional galaxies, among 28 are entirely systems, nine were previously known. determined geometric redshifts systems. agree reasonably well with spectroscopic or...
Abstract We present a multiwavelength analysis using the Submillimeter Array (SMA), James Clerk Maxwell Telescope, NOEMA, JWST, Hubble Space Telescope (HST), and Spitzer of two dusty strongly star-forming galaxies, 850.1 850.2, seen through massive cluster lens A 1489. These SMA-located sources both lie at z = 4.26 have bright dust continuum emission, but 850.2 is UV-detected Lyman-break galaxy, while undetected ≲ 2 μ m, even with deep JWST/NIRCam observations. investigate their stellar,...
Abstract We study the spatially resolved stellar populations of 444 galaxies at 0.3 < z 6.0 in two clusters (WHL 0137–08 and MACS 0647+70) a blank field, combining imaging data from Hubble Space Telescope JWST to perform spectral energy distribution (SED) modeling using piXedfit . The high spatial resolution combined with magnification gravitational lensing cluster fields allows us resolve large fraction our (109) subkiloparsec scales. At redshifts around cosmic noon higher (2.5 ≲ 6.0),...
Abstract Supernova (SN) SN H0pe is a gravitationally lensed, triply imaged, Type Ia (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster galaxies. Well-observed multiply imaged SNe provide rare opportunity to constrain Hubble constant ( H 0 ), by measuring relative time delay between images and modeling foreground mass distribution. located at z = 1.783 first with sufficient light-curve sampling long enough delays for an inference. Here we present...
Abstract Dark matter subhalos with extended profiles and density cores, globular star clusters of mass 10 6 –10 8 M ⊙ that live near the critical curves in galaxy cluster lenses can potentially be detected through their lensing magnification stars background galaxies. In this work, we study effect such have on lensed images, compare to case more well-studied microlensing by black holes curves. We find gradient distribution are important determining image properties. Both lead an asymmetry...
ABSTRACT In this study, we investigate the impact of microlensing on gravitational wave (GW) signals in LIGO−Virgo sensitivity band. Microlensing caused by an isolated point lens, with (redshifted) mass ranging from MLz ∈ (1, 105) M⊙ and parameter y (0.01, 5), can result a maximum mismatch $\sim 30~{{\ \rm per\ cent}}$ their unlensed counterparts. When &lt; 1, it strongly anticorrelates luminosity distance enhancing detection horizon signal-to-noise ratio (SNR). Biases inferred source...
We report the discovery of Mothra, an extremely magnified monster star, likely a binary system two supergiant stars, in one strongly lensed galaxies behind galaxy cluster MACS J0416.1−2403. Mothra is with spectroscopic redshift z = 2.091 portion that parsecs away from caustic. The star observed only on side critical curve negative parity but has been detectable for at least eight years, implying presence small lensing perturber. Microlenses alone cannot explain earlier observations this...
The first James Webb Space Telescope ({\it JWST}) Near InfraRed Camera (NIRCam) imaging in the field of galaxy cluster PLCK G165.7+67.0 ($z=0.35$) uncovered a Type Ia supernova (SN~Ia) at $z=1.78$, called ``SN H0pe." Three different images this one SN were detected as result strong gravitational lensing, each traversing path spacetime, thereby inducing relative delay arrival image. Follow-up {\it JWST} observations all three enabled photometric and rare spectroscopic measurements two time...
We discuss the gravitational lensing of wave signals from coalescing binaries. delineate regime where effects are significant geometric limit can be used. Further, we focus on effect micro-lensing and combined strong micro-lensing. find that with introduce time varying phase shift in signal hence lead to detectable differences observed for different images produced by lensing. This, coupled coarse localization source sky detections, make it difficult identify common origin corresponding use...
Abstract On 2022 July 8, NASA shared ( https://www.nasa.gov/feature/goddard/2022/nasa-shares-list-of-cosmic-targets-for-webb-telescope-s-first-images ) the list of five public showcase targets that have been observed with new James Webb Space Telescope (JWST) and whose data—at time writing—are expected to be released around Tuesday, 12. One these is galaxy cluster SMACS J0723.3−7327 z = 0.39), which acts as a gravitational lens was recently imaged Hubble (HST) in framework Reionization...
ABSTRACT Gravitational lensing may render individual high-mass stars detectable out to cosmological distances, and several extremely magnified have in recent years been detected redshifts $z\approx 6$. Here, we present Muspelheim, a model for the evolving spectral energy distributions of both metal-enriched metal-free at high redshifts. Using this model, argue that lensed will form highly biased sample intrinsic distribution across Hertzsprung–Russell diagram, bias typically tend favour...
ABSTRACT This work studies microlensing effects in strongly lensed gravitational wave (GW) signals corresponding to global minima images galaxy-scale lenses. We find that stellar microlenses alone are unable introduce noticeable the GW at strong lensing magnification $( {\mu})\lt 50$ with match value between unlensed and being above ${\sim }99.5~{{\ \rm per \, cent}}$ }90~{{\ of systems implying can be treated as reference signal determine amount other counterparts. Since negligible minima,...
Recent observations of caustic-crossing galaxies at redshift 0.7 ≲ z 1 show a wealth transient events. Most them are believed to be microlensing events highly magnified stars. Earlier work predicts such should common near the critical curves (CCs) galaxy clusters (“near region”), but some found relatively far away from these CCs (“far region”). We consider possibility that substructure on milliarcsecond scales (few parsecs in lens plane) is boosting signal region. study combined...
With the increase in number of observed gravitational wave (GW) signals, detecting strongly lensed GWs by galaxies has become a real possibility. Lens also contain microlenses (e.g., stars and black holes), introducing further frequency-dependent modulations GW signal within LIGO frequency range. The multiple signals given lens system have different underlying macro-magnifications ($|μ|$) are located varied microlens densities ($Σ_\bullet$), leading to levels microlensing distortions. This...
Abstract SN H0pe is a triply imaged supernova (SN) at redshift z = 1.78 discovered using the James Webb Space Telescope. In order to classify spectroscopically and measure relative time delays of its three images (designated A, B, C), we acquired NIRSpec follow-up spectroscopy spanning 0.6–5 μ m. From high signal-to-noise spectra two bright B C, first SN, whose most closely match those 1994D 2013dy, as Type Ia SN. We identify prominent blueshifted absorption features corresponding Si ii λ...
Abstract We report the discovery of an extremely magnified star at redshift z = 2.65 in James Webb Space Telescope (JWST) NIRISS pre-imaging A2744 galaxy-cluster field. The star’s background host galaxy lies on a fold caustic foreground lens, and cluster creates pair images region close to lensed star. identified bright transient one merging distance ∼0.″15 from critical curve by subtracting JWST F115W F150W imaging coadditions archival Hubble (HST) F105W F125W F140W F160W images,...
We report the discovery of a transient seen in strongly lensed arc at redshift $z_{\rm s}=1.2567$ \emph{Hubble Space Telescope} imaging Abell 370 galaxy cluster. The is detected $29.51\pm0.14$ AB mag WFC3/UVIS F200LP difference image made using observations from two different epochs, obtained framework \emph{Flashlights} program, and also visible F350LP band ($m_{\rm F350LP} \approx 30.53\pm0.76$ mag). observed on negative-parity side critical curve distance $\sim 0.6"$ it, greater than...