Christoph Saulder
A5062308654- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Advanced Statistical Methods and Models
- Astrophysics and Cosmic Phenomena
- Advanced Statistical Process Monitoring
- Gaussian Processes and Bayesian Inference
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Statistical and numerical algorithms
- Scientific Measurement and Uncertainty Evaluation
- Particle physics theoretical and experimental studies
- Inertial Sensor and Navigation
- Radio Astronomy Observations and Technology
- Advanced Measurement and Metrology Techniques
- Advanced Fluorescence Microscopy Techniques
- Impact of Light on Environment and Health
- Advanced Data Compression Techniques
Max Planck Institute for Extraterrestrial Physics
2024
Korea Astronomy and Space Science Institute
2022-2024
Korea Institute for Advanced Study
2018-2019
University of Vienna
2013-2018
European Southern Observatory
2015
European Southern Observatory
2013
Abstract Over the next 5 yr, Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on 4 m Mayall Telescope at Kitt Peak National Observatory to conduct first Stage IV dark energy galaxy survey. At z < 0.6, DESI Bright Galaxy Survey (BGS) produce most detailed map of universe during dark-energy-dominated epoch redshifts >10 million galaxies spanning 14,000 deg 2 . In this work, we present and validate final BGS target selection survey design. From Legacy...
Abstract The Dark Energy Spectroscopic Instrument (DESI) Survey has obtained a set of spectroscopic measurements galaxies to validate the final survey design and target selections. To assist in these tasks, we visually inspect DESI spectra approximately 2500 bright galaxies, 3500 luminous red (LRGs), 10,000 emission-line (ELGs) obtain robust redshift identifications. We then utilize inspected information characterize performance operation. Based on visual inspection (VI) catalogs, our...
Abstract Baryon acoustic oscillations (BAO) provide a robust standard ruler to measure the expansion history of Universe through galaxy clustering. Density-field reconstruction is now widely adopted procedure for increasing precision and accuracy BAO detection. With goal finding optimal settings be used in DESI 2024 analysis, we assess sensitivity post-reconstruction constraints different choices our analysis configuration, performing tests on blinded data from first year observations (DR1),...
Abstract In this paper, we present the estimation of systematics related to halo occupation distribution (HOD) modeling in baryon acoustic oscillations (BAO) distance measurement Dark Energy Spectroscopic Instrument (DESI) 2024 analysis. This paper focuses on study HOD for luminous red galaxies (LRG). We consider three different models LRGs, including base 5-parameter vanilla model and two extensions it, that refer as baseline extended models. The is described by 5 parameters, an...
Abstract Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a fourfold increase in number known quasars. High-accuracy classification is essential tighten constraints on cosmological parameters measured at highest redshifts DESI observes ( z > 2.0). We present spectral templates for identification and redshift estimation quasars Year 1 data release. The are comprised two eigenspectra sets, trained from Sloan Digital Sky Survey. sets...
Context. Friends-of-friends algorithms are a common tool to detect galaxy groups and clusters in large survey data. In order be as precise possible, they have carefully calibrated using mock catalogues. Aims. We create an accurate robust description of the matter distribution local Universe most up-to-date available This will provide input for specific cosmological test planned follow-up this work, useful general extragalactic research. Methods. created set group catalogues based on 2MRS...
We describe the target selection and characteristics of DESI Peculiar Velocity Survey, largest survey peculiar velocities (PVs) using both fundamental plane (FP) Tully-Fisher (TF) relationship planned to date. detail how we identify suitable early-type galaxies (ETGs) for FP late-type (LTGs) TF relation photometric data provided by Legacy Imaging Survey DR9. Subsequently, provide targets 373 533 ETGs 118 637 LTGs within 5-year footprint. validate these selections existing morphological...
Over the next five years, Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on 4m Mayall Telescope at Kitt Peak National Observatory to conduct first Stage-IV dark energy galaxy survey. At $z < 0.6$, DESI Bright Galaxy Survey (BGS) produce most detailed map of Universe during dominated epoch redshifts >10 million galaxies over 14,000 deg$^2$. In this work, we present and validate final BGS target selection survey design. From Legacy Surveys, a $r...
Aims. We aim at finding candidates of potential survivors high-redshift compact galaxies in SDSS, as targets for more detailed follow-up observations. Methods. From the virial theorem it is expected that a given mass, have stellar velocity dispersion higher than mean due to their smaller sizes. Therefore coupled with size (or mass) an appropriate method select relics, independent population properties. Based on these consideration we design set criteria using distribution early-type from...
Abstract We present the probabilistic stellar mass function (pSMF) of galaxies in DESI Bright Galaxy Survey (BGS), observed during One-percent Survey. The was one DESI’s survey validation programs conducted from 2021 April to May, before start main survey. It used same target selection and similar observing strategy as successfully spectra redshifts 143,017 r < 19.5 magnitude-limited BGS sample 95,499 fainter surface-brightness- color-selected Faint over z 0.6. derive pSMFs posteriors...
We present a calibration of the fundamental plane using SDSS Data Release 8. analysed about 93000 elliptical galaxies up to $z<0.2$, largest sample used for so far. incorporated up-to-date K-corrections and GalaxyZoo data classify in our sample. derived independent fits all five Sloan filters u, g, r, i z. A direct fit volume-weighted least-squares method was applied obtain coefficients plane, which implicitly corrects Malmquist bias. achieved an accuracy 15% as distance indicator. provide...
ABSTRACT The joint analysis of different cosmological probes, such as galaxy clustering and weak lensing, can potentially yield invaluable insights into the nature primordial Universe, dark energy, matter. However, development high-fidelity theoretical models is a necessary stepping stone. Here, we present public high-resolution lensing maps on light-cone, generated using N-body simulation suite abacussummit, accompanying mock catalogues, tuned to Early Data Release small-scale measurements...
ABSTRACT Galaxy–galaxy lensing (GGL) and clustering measurements from the Dark Energy Spectroscopic Instrument Year 1 (DESI Y1) data set promise to yield unprecedented combined-probe tests of cosmology galaxy–halo connection. In such analyses, it is essential identify characterize all relevant statistical systematic errors. We forecast covariances DESI Y1 GGL + bias due redshift evolution in lens samples. Focusing on projected correlations, we compute a Gaussian analytical covariance, using...
The Dark Energy Spectroscopic Instrument (DESI) survey will measure spectroscopic redshifts for millions of galaxies across roughly $14,000 \, \mathrm{deg}^2$ the sky. Cross-correlating targets in DESI with complementary imaging surveys allows us to and analyze shear distortions caused by gravitational lensing unprecedented detail. In this work, we a series mock catalogs ray-traced increasing sophistication estimate systematic effects on galaxy-galaxy estimators such as tangential...
We present the probabilistic stellar mass function (pSMF) of galaxies in DESI Bright Galaxy Survey (BGS), observed during One-Percent Survey. The was one DESI's survey validation programs conducted from April to May 2021, before start main survey. It used same target selection and similar observing strategy as successfully spectra redshifts 143,017 $r < 19.5$ magnitude-limited BGS sample 95,499 fainter surface brightness color selected Faint over $z 0.6$. derive pSMFs posteriors mass,...
Abstract We searched for isolated dark matter deprived galaxies within several state-of-the-art hydrodynamical simulations: Illustris, IllustrisTNG, EAGLE, and Horizon-AGN found a handful of promising objects in all except Horizon-AGN. While our initial goal was to study their properties evolution, we quickly noticed that them were located at the edge respective simulation boxes. After carefully investigating these using full particle data, concluded they are not merely caused by problem...
The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity Survey aims to measure the peculiar velocities of early and late type galaxies within DESI footprint using both Fundamental Plane Tully-Fisher relations. Direct measurements can significantly improve constraints on growth rate structure, reducing uncertainty by a factor approximately 2.5 at redshift 0.1 compared Bright Galaxy Survey's space distortion alone. We assess quality stellar velocity dispersion from spectroscopic...
The current generation of large galaxy surveys will test the cosmological model by combining multiple types observational probes. Realising statistical promise these new datasets requires rigorous attention to all aspects analysis including measurements, modelling, covariance and parameter likelihood. In this paper we present results an end-to-end simulation study designed pipeline for combination Dark Energy Spectroscopic Instrument (DESI) Year 1 redshift dataset separate weak gravitational...
Context. Backreactions from large-scale inhomogeneities may provide an elegant explanation for the observed accelerated expansion of universe without need to introduce dark energy. Aims. We propose a cosmological test specific model inhomogeneous cosmology, called timescape cosmology. Using galaxy surveys such as SDSS and 2MRS, we variation expected in $\Lambda$-CDM versus more generic differential using our own calibrations bounds suggested by Method. Our measures systematic variations...
ABSTRACT Combining different observational probes, such as galaxy clustering and weak lensing, is a promising technique for unveiling the physics of Universe with upcoming dark energy experiments. The redshift sample from Dark Energy Spectroscopic Instrument (DESI) will have significant overlap major ongoing imaging surveys specifically designed lensing measurements: Kilo-Degree Survey (KiDS), (DES), Hyper Suprime-Cam (HSC) survey. In this work, we analyse simulated catalogues to establish...
Using SDSS DR15 to its full extent, we derived fundamental plane distances over 317 000 early-type galaxies up a redshift of 0.4. In addition providing the largest sample ever calculated, as well calibrated group catalogue covering entire spectroscopic footprint far 0.5, present several improvements reaching beyond traditional definition plane. one approach, adjusted by removing systematic biases and selection effects in redshift-magnitude space, thereby greatly improving quality...