Thomas Herard-Demanche
A5028839232- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Atmospheric and Environmental Gas Dynamics
- Medical Imaging Techniques and Applications
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
Leiden University
2023-2025
ABSTRACT We present the first constraints on prevalence of z > 10 galaxies in Hubble Ultra Deep Field (HUDF) leveraging new NIRCam observations from JEMS (JWST Extragalactic Medium-band Survey). These probe redward 1.6 μm, beyond wavelength limit HST, allowing us to search for 10. indicate that highest redshift candidate identified HUDF09 data with UDFj-39546284, has a 11.5, as had been suggested analyses HUDF12/XDF data. This now confirmed JWST NIRSpec. source is thus most distant...
ABSTRACT We present the JWST cycle 1 53.8 h medium program FRESCO, short for ‘First Reionization Epoch Spectroscopically Complete Observations’. FRESCO covers 62 arcmin2 in each of two GOODS/CANDELS fields a total area 124 exploiting JWST’s powerful new grism spectroscopic capabilities at near-infrared wavelengths. By obtaining ∼2 deep NIRCam/grism observations with F444W filter, yields unprecedented spectra R ∼ 1600 covering 3.8–5.0 µm most galaxies NIRCam field view. This setup enables...
Abstract We report the detection of a 13σ Hα emission line from HDF850.1 at z = 5.188 ± 0.001 using FRESCO NIRCam F444W grism observations. Detection in is noteworthy, given its high far-IR luminosity, substantial dust obscuration, and historical challenges deriving redshift. shows clear imaging data, distributed between northern southern component, mirroring that seen [CII] Plateau de Bure Interferometer. Modeling SED each component separately, we find has higher mass, star formation rate...
ABSTRACT We present high-resolution ($\sim 0.14$ arcsec = 710 pc) Atacama Large Millimetre/submillimetre Array [C ii] 158 $\mu$m and dust continuum follow-up observations of REBELS-25, a ii]-luminous ($L_{\mathrm{[CII]}}=(1.7\pm 0.2)\times 10^9\, \mathrm{L_{\odot }}$) galaxy at redshift $z=7.3065\pm 0.0001$. These high-resolution, high signal-to-noise allow us to study the sub-kpc morphology kinematics this massive ($M_* 8^{+4}_{-2} \times 10^9 \mathrm{{\rm M}_{\odot star-forming...
ABSTRACT We present the census of H $\beta$ + [${\rm O\, {\small III}}$] $4960,5008\rm{\mathring{\rm\,A}}$ emitters at $6.8\lt z\lt 9.0$ from JWST FRESCO survey over 124 arcmin$^2$ in GOODS-North and GOODS-South fields. Our unbiased spectroscopic search results 137 spectroscopically confirmed galaxies with observed fluxes $f_{\rm { [{\rm III}}]}}\gtrsim 1\times 10^{-18}\ \rm {ergs}\ {s}^{-1} \ {cm}^{-2}$. The rest-frame optical line ratios median stacked spectrum (median $M_{\rm...
Over the past decade, existence of a substantial population optically invisible, massive galaxies at $z\gtrsim3$ has been implied from mid-infrared to millimeter observations. With unprecedented sensitivity JWST, such extremely galaxy candidates have immediately identified even $z>7$, in much larger numbers than expected. These discoveries raised hot debate. If confirmed, early, high-mass challenge current models formation. However, lack spectroscopic confirmations leads uncertain stellar...
Metallicity is a crucial tracer of galaxy evolution, providing insights into gas accretion, star formation, and feedback. At high redshift, these processes reveal how early galaxies assembled enriched their interstellar medium. In this work, we present rest-frame optical spectroscopy 12 massive ($\log(M_*/\mathrm{M_{\odot}})>9$) at $z\sim 6$-$8$ from the REBELS ALMA large program, observed with JWST NIRSpec/IFU in prism mode. These observations span emission lines [OII]$\lambda$3727,9 to...
We present deep ALMA observations targeting the [CII]$_{158\mu m}\,$ line in JADES-GS-z14-0, most distant known galaxy at z=14.1793. do not detect our observations, implying a luminosity of $<$6$\times10^7$ L$_{\odot}$ (3$\sigma$) for target. Comparing this with detected [OIII]$_{88\mu line, we constrain [OIII]/[CII] ratio to be $>$3.5, significantly improving probe ionization parameter $U$. The observed is higher than analogues local universe, but consistent galaxies $z\approx6$-9. Through...
We present the first constraints on prevalence of z>10 galaxies in Hubble Ultra Deep Field (HUDF) leveraging new NIRCam observations from JEMS (JWST Extragalactic Medium-band Survey). These probe redward 1.6$μ$m, beyond wavelength limit HST, allowing us to search for z>10. indicate that highest redshift candidate identified HUDF09 data with UDFj-39546284, has a z>11.5, as had been suggested analyses HUDF12/XDF data. This now confirmed JWST NIRSpec. source is thus most distant galaxy...
We present the first results on spatial distribution of star formation in 454 star-forming galaxies at $4.8<z<6.5$ using H-Alpha emission-line maps and F444W imaging tracing stellar continuum from JWST FRESCO NIRCam Slitless Spectroscopy. Star-forming with masses $6.8\leq$log($M_{*}/\mathrm{M}_{\odot}$)$<11.1$ have positive equivalent width profiles, providing direct evidence for inside-out growth just after epoch reionisation. GALFIT is used to calculate half-light radii, $R_{\mathrm{eff}}$...
We present high resolution ($\sim0.14$" = 710 pc) ALMA [CII] 158$\mu$m and dust continuum follow-up observations of REBELS-25, a [CII]-luminous ($L_{\mathrm{[CII]}}=(1.7\pm0.2)\times 10^9 \mathrm{L_{\odot}}$) galaxy at redshift $z=7.3065\pm0.0001$. These resolution, signal-to-noise allow us to study the sub-kpc morphology kinematics this massive ($M_* 8^{+4}_{-2} \times \mathrm{M_{\odot}}$) star-forming (SFR$_{\mathrm{UV+IR}} 199^{+101}_{-63} \mathrm{M_{\odot}} \mathrm{yr}^{-1}$) in Epoch...
We present the first results on spatial distribution of star formation in 454 star-forming galaxies just after epoch reionisation (4.8 < z 6.5) using H α emission-line maps and F444W imaging that traces stellar continuum from JWST FRESCO NIRCam Slitless Spectroscopy Survey. The equivalent width profiles across main sequence at ∼ 5.3 with masses 6.8≤ log( M * /M ⊙ ) 11.1 increase radius, which provides direct evidence for inside-out growth reionisation. GALFIT was used to calculate...
We report the first successful ALMA follow-up observations of a secure $z > 10$ JWST-selected galaxy, by robustly detecting ($6.6\sigma$) [OIII]$_{88\mu m}\,$ line in JADES-GS-z14-0 (hereafter GS-z14). The detection yields spectroscopic redshift $z=14.1793\pm0.0007$, and increases precision on prior measurement $z=14.32_{-0.20}^{+0.08}$ from NIRSpec $\gtrsim$180$\times$. Moreover, is consistent with that previously determined tentative ($3.6\sigma$) CIII]$_{1907,1909}$ ($z=14.178\pm0.013$),...
We report the detection of a 13$\sigma$ H$\alpha$ emission line from HDF850.1 at $z=5.188\pm0.001$ using FRESCO NIRCam F444W grism observations. Detection in is noteworthy, given its high far-IR luminosity, substantial dust obscuration, and historical challenges deriving redshift. shows clear imaging data, distributed between northern southern component, mirroring that seen [CII] Plateau de Bure Interferometer. Modeling SED each component separately, we find has higher mass, star formation...