Vital Fernández
A5076224043- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Plant Surface Properties and Treatments
- Atmospheric Ozone and Climate
- Spectroscopy and Chemometric Analyses
- Fluid Dynamics and Heat Transfer
- Electrohydrodynamics and Fluid Dynamics
- Adaptive optics and wavefront sensing
- Cosmology and Gravitation Theories
- Atomic and Molecular Physics
- Silicon and Solar Cell Technologies
- Atmospheric and Environmental Gas Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Calibration and Measurement Techniques
- Material Properties and Applications
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Carcinogens and Genotoxicity Assessment
- Astrophysics and Cosmic Phenomena
- Scientific Research and Discoveries
University of La Serena
2021-2024
University of Michigan
2024
National Institute of Astrophysics, Optics and Electronics
2018-2019
Office National d'Études et de Recherches Aérospatiales
2009-2011
We report the discovery of a candidate galaxy with photo-z z~12 in first epoch JWST Cosmic Evolution Early Release Science (CEERS) Survey. Following conservative selection criteria we identify source robust z_phot = 11.8^+0.3_-0.2 (1-sigma uncertainty) m_F200W=27.3, and >7-sigma detections five filters. The is not detected at lambda < 1.4um deep imaging from both HST JWST, has faint ~3-sigma F150W F160W, which signal Ly-alpha break near red edge filters, implying z~12. This object (Maisie's...
Abstract We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 − 13 and M UV ∈ [ −21, −18] newly identified in NIRCam images the Cosmic Evolution Early Release Science Survey. confirm emission line 7 galaxies at = 7.762–8.998 using spectra ∼1–5 μ m either prism or its three medium-resolution ( R ∼ 1000) gratings. For candidates, we achieve a high confirmation rate ≃90%, which validates classical dropout selection from photometry. No robust lines...
We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from the Cosmic Evolution Early Release Science Survey (CEERS) NIRCam imaging with photometric redshifts z_phot>8. measure emission line z=7.65 and 8.64 for two galaxies, z=9.77(+0.37,-0.29) 10.01(+0.14,-0.19) others via detection continuum breaks consistent Lyman-alpha opacity a mostly neutral intergalactic medium. The presence (absense) strong (strong lines) give high confidence that these are at z>9.6, but break-derived...
Lyman Break Galaxy (LBG) candidates at z>10 are rapidly being identified in JWST/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of rest-frame UV photons, these sources expected drop out bluer filters while well detected redder filters. However, here we show that dust-enshrouded star-forming galaxies lower redshifts (z<7) may also mimic near-infrared (near-IR) colors LBGs, representing potential contaminants LBG candidate samples. First, analyze...
ABSTRACT Most of the hydrogen in intergalactic medium (IGM) was rapidly ionized at high redshifts. While observations have established that reionization occurred, observational constraints on high-redshift ionizing emissivity remain elusive. Here, we present a new analysis Low-redshift Lyman Continuum Survey (LzLCS) and literature observations, combined sample 89 star-forming galaxies redshifts near 0.3 with Hubble Space Telescope their continua (or Continuum, LyC). We find strong (6σ...
We present rest-frame optical emission-line flux ratio measurements for five $z>5$ galaxies observed by the JWST Near-Infared Spectrograph (NIRSpec) in SMACS 0723 Early Release Observations. add several quality-control and post-processing steps to NIRSpec pipeline reduction products order ensure reliable relative calibration of emission lines that are closely separated wavelength, despite uncertain \textit{absolute} spectrophotometry current version reductions. Compared $z\sim3$ literature,...
We report observational evidence of highly turbulent ionized gas kinematics in a sample 20 Lyman continuum (LyC) emitters (LCEs) at low redshift ( z ∼ 0.3). Detailed Gaussian modeling optical emission line profiles high-dispersion spectra consistently shows that both bright recombination and collisionally excited lines can be fitted as one or two narrow components with intrinsic velocity dispersion σ 40 − 100 km s −1 , addition to broader component 300 which contributes up ∼40% the total...
During the first 500 million years of cosmic history, stars and galaxies formed, seeding Universe with heavy elements eventually reionizing intergalactic medium. Observations JWST have uncovered a surprisingly high abundance candidates for early star-forming galaxies, distances (redshifts, $z$), estimated from multi-band photometry, as large $z\approx 16$, far beyond pre-JWST limits. While generally robust, such photometric redshifts can suffer degeneracies occasionally catastrophic errors....
Abstract Spectroscopic studies of extreme-ionization galaxies (EIGs) are critical to our understanding exotic systems throughout cosmic time. These EIGs exhibit spectral features requiring >54.42 eV photons: the energy needed ionize helium into He 2+ fully and emit ii recombination lines. can probe stellar populations or accretion onto intermediate-mass black holes (∼10 2 –10 5 M ⊙ ), which possibly key contributors reionization Universe. To facilitate use as probes high-ionization...
The primordial helium abundance YP is calculated using sulphur as metallicity tracer in the classical methodology (with an extrapolation of Y to zero metals). value, YP, S= 0.244 ± 0.006, good agreement with estimate from Planck experiment, well as, determinations literature oxygen tracer. chemical analysis includes substraction nebular continuum and stellar computed simple population synthesis grids. S+2 content measured near-infrared |$\left[\mathrm{ S}\,\mathrm{ III}\right]\lambda \lambda...
ABSTRACT We present a spectroscopic survey of Ly α emitters in the Extended Groth Strip (EGS) field, targeting regime near Epoch Reionization. Using Keck/DEep Imaging Multi-Object Spectrograph, we observed 947 high-z candidates with photometric redshifts from 3 &lt; zphot 7 and down to an H-band (Hubble Space Telescope/Wide Field Camera F160W) magnitude limit &lt;27.5. Observations were taken over course eight nights, integration times ranging 4 7.8 h. Our secured 137 unique...
The upcoming generation of telescopes, instruments, and surveys is poised to usher in an unprecedented "Big Data" era the field astronomy. Within this context, even seemingly modest tasks such as spectral line analyses could become increasingly challenging for astronomers. In paper, we announce release ${\rm L{\small I}M{\small E}}$. This package tailored multidisciplinary observations with long-slit integral spectroscopy (IFS) support. E}}$ functions encompass reading observational files,...
ABSTRACT This work focuses on the gas chemical composition of CGCG007-025. compact dwarf is undergoing a galaxy wide star-forming burst, whose spatial behaviour has been observed by VLT/MUSE. We present new line measurement library to treat almost 7800 voxels. The direct method analysis limited 484 voxels with good detection $[\mathrm{S}\, {\small III}]6312\, \mathring{\rm A}$ temperature diagnostic line. recombination fluxes are corrected for stellar absorption via population synthesis....
Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and active galactic nucleus (AGN) powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN population across cosmic epochs. To mitigate effect, it crucial observe at longer wavelengths in near-infrared (near-IR), which less affected by dust attenuation can thus provide better description intrinsic properties galaxies. regime have not...
We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from the Cosmic Evolution Early Release Science Survey (CEERS) NIRCam imaging with photometric redshifts z_phot>8. measure emission line z=7.65 and 8.64 for two galaxies, z=9.77(+0.37,-0.29) 10.01(+0.14,-0.19) others via detection continuum breaks consistent Lyman-alpha opacity a mostly neutral intergalactic medium. The presence (absense) strong (strong lines) give high confidence that these are at z>9.6, but...
Abstract We present the Cosmic Evolution Early Release Science (CEERS) Survey, a 77.2 hr Director’s Discretionary Program. CEERS demonstrates, tests, and validates efficient extragalactic surveys using coordinated, overlapping parallel observations with JWST instrument suite, including NIRCam MIRI imaging, NIRSpec low- ( R ∼ 100) medium- 1000) resolution spectroscopy, slitless grism 1500) spectroscopy. targets Hubble Space Telescope–observed region of Extended Groth Strip field, supported by...
This work presents a Bayesian algorithm to fit the recombination and collisionally excited line spectra of gas photoionized by clusters young stars. The current model consists in fourteen dimensions: two electron temperatures, one density, extinction coefficient, optical depth on $HeI$ lines nine ionic species. results are very good agreement with those previously published using traditional methodology. probabilistic programming library PyMC3 was chosen explore parameter space via NUTs...
The properties that govern the production and escape of hydrogen ionizing photons (Lyman continuum, LyC; with energies >13.6 eV) in star-forming galaxies are still poorly understood, but they key to identifying characterizing sources reionized Universe. Here we empirically explore relationship between hardness radiation LyC leakage a large sample low-$z$ from recent Hubble Space Telescope Low-$z$ Lyman Continuum Survey. Using Sloan Digital Sky Survey stacks deep XShooter observations,...
Context. The ultraviolet continuum traces young stars while the near-infrared unveils older stellar populations and dust-obscured regions. Balmer emission lines provide insights into gas properties objects but are highly affected by dust attenuation. Paschen suffer less attenuation can be used to measure star formation rates (SFRs) in star-forming regions obscured clouds. Aims. We present a new way of combining spectro-photometric data order test robustness SFRs mass estimates sources...
Nearby metal-poor starburst dwarf galaxies present a unique opportunity to probe the physics of high-density star formation with detail and sensitivity unmatched by any observation high-z Universe. Here we first results from chemodynamical study nearby, gas-rich CGCG 007-025. We use VLT/MUSE integral field spectroscopy characterise properties star-forming (SF) gas, its metal content kinematics. The rate (SFR) surface density presents clumpy distribution, brightest knot hosting 5 Myr young,...
We report the discovery of a candidate galaxy with photo-z z~12 in first epoch JWST Cosmic Evolution Early Release Science (CEERS) Survey. Following conservative selection criteria we identify source robust z_phot = 11.8^+0.3_-0.2 (1-sigma uncertainty) m_F200W=27.3, and >7-sigma detections five filters. The is not detected at lambda < 1.4um deep imaging from both HST JWST, has faint ~3-sigma F150W F160W, which signal Ly-alpha break near red edge filters, implying z~12. This object...
Low-metallicity, compact starburst galaxies referred to as Green Peas (GPs) provide a unique window study galactic evolution across cosmic epochs. In this work, we present new deep optical spectra for three GPs from OSIRIS at the 10m Gran Telescopio Canarias (GTC), which are studied using state-of-the-art methodology. A stellar population synthesis is conducted with 1098 spectral templates. The methodology succeeds characterising populations 0.5 Myrs 10 Gyrs. light distribution shows large...
Abstract We present a sample of 1165 extreme emission-line galaxies (EELGs) at 4 < z 9 selected using James Webb Space Telescope (JWST) NIRCam photometry in the Cosmic Evolution Early Release Science (CEERS) program. use simple method to photometrically identify EELGs with H β + [O iii ] (combined) or α emission observed-frame equivalent width (EW) > 5000 Å. JWST/NIRSpec spectroscopic observations subset (34) validate our selection method: All spectroscopically observed confirm...