Hans‐Walter Rix
A5028539980- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- CCD and CMOS Imaging Sensors
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Black Holes and Theoretical Physics
- Relativity and Gravitational Theory
- Plant Water Relations and Carbon Dynamics
- Advanced Statistical Methods and Models
- Geomagnetism and Paleomagnetism Studies
Max Planck Institute for Astronomy
2016-2025
Airbus (Germany)
2022
Max Planck Society
2007-2019
Max Planck Innovation
2019
University of Göttingen
2018
Max Planck Institute for Extraterrestrial Physics
2013
Trinity House
2013
European Space Research and Technology Centre
2011
European Southern Observatory
2011
University of Arizona
1988-2008
Abstract Multi-epoch radial velocity measurements of stars can be used to identify stellar, substellar, and planetary-mass companions. Even a small number observation epochs informative about companions, though there multiple qualitatively different orbital solutions that fit the data. We have custom-built Monte Carlo sampler ( The Joker ) delivers reliable (and often highly multimodal) posterior samplings for companion parameters given sparse Here we use perform search companions 96,231 red...
We present a two-dimensional fitting algorithm (GALFIT) designed to extract structural components from galaxy images, with emphasis on closely modeling light profiles of spatially well-resolved, nearby galaxies observed the Hubble Space Telescope. Our improves previous techniques in two areas: by being able simultaneously fit an arbitrary number and optimization computation speed, suited for working large images. use models such as "Nuker" law, Sérsic (de Vaucouleurs) profile, exponential...
The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) is designed to document the first third of galactic evolution, over approximate redshift (z) range 8--1.5. It will image >250,000 distant galaxies using three separate cameras on Hubble Space Telescope, from mid-ultraviolet near-infrared, and find measure Type Ia supernovae at z>1.5 test their accuracy as standardizable candles for cosmology. Five premier multi-wavelength sky regions are selected, each with...
The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around second Earth–Sun Lagrange point. have four instruments: near-IR camera, multiobject spectrograph, and tunable filter imager cover wavelength range, 0.6 < ; 5.0 μ m, while mid-IR instrument do both imaging spectroscopy from 29 m. JWST science goals are divided themes. key objective of End Dark Ages: First Light...
We present a two-dimensional (2D) fitting algorithm (Galfit, ver. 3) with new capabilities to study the structural components of galaxies and other astronomical objects in digital images. Our technique improves on previous 2D algorithms by allowing for irregular, curved, logarithmic power-law spirals, ring, truncated shapes otherwise traditional parametric functions like Sérsic, Moffat, King, Ferrer, etc., profiles. One can mix match these shape features freely, or without constraints, apply...
This paper describes the Hubble Space Telescope imaging data products and reduction procedures for Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). survey is designed to document evolution of galaxies black holes at $z\sim1.5-8$, study Type Ia SNe beyond $z>1.5$. Five premier multi-wavelength sky regions are selected, each with extensive multiwavelength observations. The primary CANDELS consist obtained in Wide Field Camera 3 / infrared channel (WFC3/IR) UVIS channel,...
We have reexamined the relation between mass of central black holes in nearby galaxies, Mbh, and stellar surrounding spheroid or bulge, Mbulge. For a total 30 galaxies bulge masses were derived through Jeans equation modeling adopted from dynamical models literature. In mass-to-light ratios, spheroids bulges span range factor 8. The related to well-determined hole taken With these improved values for compared Magorrian et al., our redetermination Mbulge, we find that Mbh-Mbulge becomes very...
We present the rest-frame colors and luminosities of ~25000 m_R<24 galaxies in redshift range 0.2
The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained ≈240,000 moderate-resolution (R ∼ 1800) spectra from 3900 Å to 9000 of fainter Milky Way stars (14.0 < g 20.3) a wide variety spectral types, both main-sequence evolved objects, with the goal studying kinematics populations our Galaxy its halo. are clustered in 212 regions spaced over three quarters sky. Radial velocity accuracies at 18, degrading 20. For signal-to-noise ratio >10 per resolution element,...
We present five new satellites of the Milky Way discovered in Sloan Digital Sky Survey (SDSS) imaging data, four which were followed up with either Subaru or Isaac Newton Telescopes. They include probable dwarf galaxies—one each constellations Coma Berenices, Canes Venatici, Leo, and Hercules—together one unusually extended globular cluster, Segue 1. provide distances, absolute magnitudes, half-light radii, color-magnitude diagrams for all satellites. The morphological features are generally...
Spectroscopic+photometric redshifts, stellar mass estimates, and rest-frame colors from the 3D-HST survey are combined with structural parameter measurements CANDELS imaging to determine galaxy size–mass distribution over redshift range 0 < z 3. Separating early- late-type galaxies on basis of star-formation activity, we confirm that early-type average smaller than at all find a significantly different rate size evolution fixed mass, fast for population, Reff∝(1 + z)−1.48, moderate z)−0.75....
We derive new constraints on the mass of Milky Way's dark matter halo, based 2401 rigorously selected blue horizontal-branch halo stars from SDSS DR6. This sample enables construction full line-of-sight velocity distribution at different galactocentric radii. To interpret these distributions, we compare them to matched mock observations drawn two cosmological galaxy formation simulations designed resemble Way. procedure results in an estimate circular curve ~60 kpc, which is found be...
We explore the redshift evolution of specific star formation rate (SSFR) for galaxies different stellar mass by drawing on a deep 3.6 μm selected sample >105 in 2 deg2 COSMOS field. The average (SFR) subsets these is estimated with stacked 1.4 GHz radio continuum emission. separately consider total and subset that shows evidence substantive recent rest-frame optical spectral energy distributions. At redshifts 0.2 < z 3 both populations show strong mass-independent decrease their SSFR toward...
We identify new structures in the halo of Milky Way Galaxy from positions, colors and magnitudes five million stars detected Sloan Digital Sky Survey. Most these are within 1.26 degrees celestial equator. present color-magnitude diagrams (CMDs) for two previously discovered, tidally disrupted structures. The CMDs turnoff consistent with those Sagittarius dwarf galaxy, as had been predicted. In one direction, we even able to detect a clump red stars, similar that dwarf, spread across 110...
The 3D-HST and CANDELS programs have provided WFC3 ACS spectroscopy photometry over ~900 square arcminutes in five fields: AEGIS, COSMOS, GOODS-North, GOODS-South, the UKIDSS UDS field. All these fields a wealth of publicly available imaging datasets addition to HST data, which makes it possible construct spectral energy distributions (SEDs) objects wide wavelength range. In this paper we describe photometric analysis ancillary data at wavelengths 0.3um 8um. Objects were selected near-IR...
We present ∼kiloparsec spatial resolution maps of the CO-to-H2 conversion factor (αCO) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. have simultaneously solved for αCO DGR by assuming that is approximately constant on kiloparsec scales. With this assumption, we can combine dust mass surface density, CO-integrated intensity, H i column density to solve both with no assumptions about their value or dependence metallicity other parameters. Such a study has just become...
We study the process of cosmic reionization and estimate ionizing background in IGM using Lyman series absorption spectra four quasars at 5.710^{-3} z~6. At this redshift, mass-averaged neutral hydrogen fraction is larger than 1%; mildly overdense regions (delta > 3) are still mostly comoving mean free path photons shorter 8 Mpc. Comparison with simulations cosmological shows that observed properties z~6 typical those era end overlap stage when individual HII merge. Thus, marks epoch. The...
(Abridged) We introduce a novel technique to construct spatially resolved maps of stellar mass surface density in galaxies based on optical and near IR imaging. use optical/NIR colour(s) infer effective mass-to-light ratios (M/L) at each pixel, which are then multiplied by the brightness obtain local density. build look-up tables express M/L as function marginalizing over Monte Carlo library 50,000 population synthesis (SPS) models Charlot & Bruzual (2007), include revised prescription...
We present global structural parameter measurements of 109,533 unique, H_F160W-selected objects from the CANDELS multi-cycle treasury program. Sersic model fits for these are produced with GALFIT in all available near-infrared filters (H_F160W, J_F125W and, a subset, Y_F105W). The parameters best-fitting models (total magnitude, half-light radius, index, axis ratio, and position angle) made public, along newly constructed point spread functions each field filter. Random uncertainties...
We present a first analysis of deep 24 micron observations with the Spitzer Space Telescope sample nearly 1500 galaxies in thin redshift slice, 0.652x10^10 solar masses) are undergoing period intense star formation above their past-averaged SFR. In contrast, less than 1% equally-massive local universe have similarly activity. Morphologically-undisturbed dominate total infrared luminosity density and SFR density: at z~0.7, more half intensely star-forming spiral morphologies, whereas \~30%...