Guillaume Mahler
A5013976691- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Pulsars and Gravitational Waves Research
- Calibration and Measurement Techniques
- Photocathodes and Microchannel Plates
- Dark Matter and Cosmic Phenomena
- Advanced Optical Sensing Technologies
- History and Developments in Astronomy
- Ocular and Laser Science Research
- Radiation Therapy and Dosimetry
- Gaussian Processes and Bayesian Inference
- Real-time simulation and control systems
- Astro and Planetary Science
- Advanced Measurement and Metrology Techniques
Durham University
2021-2025
University of Michigan
2018-2023
Indiana Cancer Consortium
2023
Centre de Recherche Astrophysique de Lyon
2015-2021
Université Claude Bernard Lyon 1
2015-2020
Centre National de la Recherche Scientifique
2017-2020
École Normale Supérieure de Lyon
2017-2020
University College London
2020
Michigan United
2020
Observatoire de Lyon
2015-2016
One of the main goals JWST is to study first galaxies in Universe. We present a systematic photometric analysis very distant deep field towards massive lensing cluster SMACS0723. As result, we report discovery two galaxy candidates at $z\sim16$, only $250$ million years after Big Bang. also identify $z\sim 12$ and 6 9-11$. Our search extended out $z\lesssim21$ by combining color information across seven NIRCam NIRISS filters. By modelling Spectral Energy Distributions (SEDs) with...
Abstract We present the survey design, implementation, and outlook for COSMOS-Web, a 255 hr treasury program conducted by James Webb Space Telescope in its first cycle of observations. COSMOS-Web is contiguous 0.54 deg 2 NIRCam imaging four filters (F115W, F150W, F277W, F444W) that will reach 5 σ point-source depths ranging ∼27.5–28.2 mag. In parallel, we obtain 0.19 MIRI one filter (F770W) reaching ∼25.3–26.0 build on rich heritage multiwavelength observations data products available COSMOS...
We present the clump populations detected in 18 lensed galaxies at redshifts 1 to 8.5 within lensing cluster field SMACS0723. The recent JWST Early Release Observations of this poorly known region sky have revealed numerous point-like sources and surrounding their host galaxies, undetected shallower HST images. use multiband photometry model galaxy estimate intrinsic sizes magnitudes stellar clumps. derive optical restframe effective radii from $<$10 100s pc masses ranging $\sim10^5$ $10^9$...
Star cluster formation in the early universe and their contribution to reionization remains date largely unconstrained. Here we present JWST/NIRCam imaging of most highly magnified galaxy known at z ~ 6, Sunrise arc. We identify six young massive star clusters (YMCs) with measured radii spanning 20 pc down 1 (corrected for lensing magnification), estimated stellar masses $10^{(6-7)}$ Msun, ages 1-30 Myr based on SED fitting photometry 8 filters extending rest-frame 7000A. The resulting mass...
Abstract The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. 1 ). However, it an intrinsically ultraviolet faint galaxy, in range of those now thought to drive reionization Universe 2–4 . Hitherto smallest features resolved a galaxy comparable are between few hundreds tens parsecs (pc) 5,6 Here we report JWST observations Gems. light into five star clusters located region smaller than 70 pc. They exhibit minimal dust attenuation low...
We present an analysis of MUSE observations obtained on the massive Frontier Fields cluster Abell 2744. This new dataset covers entire multiply-imaged region around core. measure spectroscopic redshifts for HST-selected continuum sources together with line emitters blindly detected in datacube. The combined catalog consists 514 (with 414 identifications), including 156 members and 326 magnified background sources. use this redshift information to perform a strong-lensing all multiple images...
Spectroscopic surveys of massive galaxy clusters reveal the properties faint background galaxies, thanks to magnification provided by strong gravitational lensing. We present a systematic analysis integral-field-spectroscopy observations 12 clusters, conducted with Multi Unit Explorer (MUSE). All data were taken under very good seeing conditions (0.6") in effective exposure times between two and 15 hrs per pointing, for total 125 hrs. Our cover solid angle ~23 arcmin$^2$ direction many which...
We present a strong lensing analysis on the massive cluster Abell 370 (A370; z = 0.375), using combination of deep multi-band Hubble Space Telescope (HST) imaging and Multi-Unit Spectroscopic Explorer (MUSE) spectroscopy. From only two hours MUSE data, we are able to measure 120 redshifts in Southern BCG area, including several multiply-imaged lens systems. In total, increase number systems with secure redshift from 4 15, nine which newly discovered. Of these, eight located at > 3, greatly...
We present the deepest study to date of Lya luminosity function (LF) in a blank field using blind integral spectroscopy from MUSE. constructed sample 604 emitters (LAEs) across redshift range 2.91 < z 6.64 automatic detection software Hubble Ultra Deep Field. calculate accurate total fluxes capturing low surface brightness extended emission now known be generic property high-redshift star-forming galaxies. simulated realistic LAEs characterise selection our samples, and performed...
The Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) is a 101 orbit + parallel Cycle 25 Hubble Space Telescope Treasury program taking data from 2018-2020. BUFFALO will expand existing coverage of the (HFF) in WFC3/IR F105W, F125W, F160W ACS/WFC F606W F814W around each six HFF clusters flanking fields. This additional area has not been observed by HST but already covered deep multi-wavelength datasets, including Spitzer Chandra. As with original program, designed to take...
The gravitationally lensed star WHL0137-LS, nicknamed Earendel, was identified with a photometric redshift $z_{phot} = 6.2 \pm 0.1$ based on images taken the Hubble Space Telescope. Here we present James Webb Telescope (JWST) Near Infrared Camera (NIRCam) of Earendel in 8 filters spanning 0.8--5.0$\mu$m. In these higher resolution images, remains single unresolved point source lensing critical curve, increasing lower limit magnification to $\mu > 4000$ and restricting plane radius further $r...
Abstract We report the discovery of four galaxy candidates observed 450–600 Myr after Big Bang with photometric redshifts between z ∼ 8.3 and 10.2 measured using James Webb Space Telescope (JWST) NIRCam imaging cluster WHL0137−08 in eight filters spanning 0.8–5.0 μ m, plus nine Hubble 0.4–1.7 m. One candidate is gravitationally lensed a magnification 8, while other three are located nearby module expected magnifications ≲ 1.1. Using SED fitting, we estimate stellar masses these galaxies...
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...
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...
Abstract Exploiting the fundamentally achromatic nature of gravitational lensing, we present a lens model for massive galaxy cluster SMACS J0723.3−7323 (SMACS J0723; z = 0.388) that significantly improves upon earlier work. Building on strong-lensing constraints identified in prior Hubble Space Telescope (HST) observations, mass utilizes 21 multiple-image systems, 17 which were newly discovered Early Release Observation data from JWST. The resulting maps distribution to an rms spatial...
Abstract Extreme, young stellar populations are considered to be the primary contributor cosmic reionization. How Lyman continuum (LyC) escapes these galaxies remains highly elusive, and it is challenging observe this process in actual LyC emitters without resolving relevant physical scales. We investigate Sunburst Arc, a strongly lensed emitter at z = 2.37 that reveals an exceptionally small-scale (tens of parsecs) region high escape. The small (<100 pc) LyC-leaking has extreme...
ABSTRACT The distribution of mass in galaxy-scale strong gravitational lenses is often modelled as an elliptical power-law plus ‘external shear’, which notionally accounts for neighbouring galaxies and cosmic shear along our line sight. A small amount external could come from these sources, but we show that the vast majority does not. Except a handful rare systems, best-fitting values do not correlate with independent measurements line-of-sight shear: weak lensing 45 Hubble Space Telescope...
We present a high-precision mass model of the galaxy cluster MACS J1149.6+ 2223, based on strong gravitational lensing analysis Hubble Space Telescope Frontier Fields (HFF) imaging data and spectroscopic follow-up with Gemini/Gemini Multi-Object Spectrographs (GMOS) Very Large (VLT)/Multi Unit Spectroscopic Explorer (MUSE). Our includes 12 new multiply imaged galaxies, bringing total to 22, composed 65 individual lensed images. Unlike first two HFF clusters, Abell 2744 J0416.1−2403, J1149...
While low-luminosity galaxies dominate number counts at all redshifts, their contribution to cosmic Reionization is poorly understood due a lack of knowledge physical properties. We isolate sample 35 z~4-5 continuum-faint Lyman-alpha emitters from deep VLT/MUSE spectroscopy and directly measure Halpha emission using stacked Spitzer/IRAC Ch. 1 photometry. Based on Hubble Space Telescope imaging, we determine that the average UV continuum magnitude fainter than -16 (~0.01 L_star), implying...
We describe the observations and resultant galaxy cluster catalog from 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via Sunyaev–Zel'dovich (SZ) effect confirmed with a combination of archival targeted follow-up data, making particular use data Dark Energy (DES). With incomplete we have as clusters 244 266 candidates at detection significance ξ ≥ 5 an additional 204 systems 4 < 5. The sample has median mass redshift z = 0.49, 44 strong gravitational lenses in...
We present an updated strong-lensing analysis of the massive cluster Abell 370 (A370), continuing work first presented in Lagattuta et al. (2017). In this new analysis, we take advantage deeper imaging data from Hubble Space Telescope (HST) Frontier Fields program, as well a large spectroscopic mosaic obtained with Multi-Unit Spectroscopic Explorer (MUSE). Thanks to extended coverage mosaic, probe full 3D distribution galaxies field, giving us unique picture structure and its surroundings....
ABSTRACT We present an extension to a Sunyaev–Zel’dovich Effect (SZE) selected cluster catalogue based on observations from the South Pole Telescope (SPT); this extends lower signal noise than previous SPT–SZ and therefore includes mass clusters. Optically derived redshifts, centres, richnesses, morphological parameters together with contamination completeness statistics are extracted using multicomponent matched filter (MCMF) algorithm applied S/N &gt; 4 candidate list Dark Energy...
Strong gravitational lensing by galaxy clusters is a fundamental tool to study dark matter and constrain the geometry of Universe. Recently, Hubble Space Telescope Frontier Fields programme has allowed significant improvement mass magnification measurements but models still have residual root mean square between 0.2 arcsec few arcsec- onds, not yet completely understood. Systematic errors be better understood treated in order use strong as reliable cosmological probes. We analysed two...