J. H. Knapen
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View article: Simulation-based inference of galaxy properties from JWST pixels
Simulation-based inference of galaxy properties from JWST pixels Open
The spectral energy distributions (SEDs) of galaxies offer detailed insights into their stellar populations, capturing key physical properties such as stellar mass, star formation history (SFH), metallicity, and dust attenuation. However, …
View article: Negative gas-phase metallicity gradients in the narrow-line region and galactic disc of local galaxies hosting active galactic nuclei
Negative gas-phase metallicity gradients in the narrow-line region and galactic disc of local galaxies hosting active galactic nuclei Open
The gas-phase metallicity distribution in galaxies offers significant information on their evolution. We report the discovery of negative radial gradients in the gas-phase metallicity of the narrow-line region (NLR) of the nine galaxies in…
View article: <i>Euclid</i> preparation
<i>Euclid</i> preparation Open
The European Space Agency’s Euclid mission will observe approximately 14000 deg 2 of the extragalactic sky and deliver high-quality imaging of a large number of galaxies. The depth and high spatial resolution of the data will enable a deta…
View article: <i>Euclid</i> : Early Release Observations – Interplay between dwarf galaxies and their globular clusters in the Perseus galaxy cluster
<i>Euclid</i> : Early Release Observations – Interplay between dwarf galaxies and their globular clusters in the Perseus galaxy cluster Open
We present an analysis of globular clusters (GCs) of dwarf galaxies in the Perseus galaxy cluster that explores the relationship between dwarf galaxy properties and their GCs. Our focus is on GC numbers ( N GC ) and GC half-number radii ( …
View article: Euclid preparation LXXIX. Using mock low surface brightness dwarf galaxies to probe Euclid Wide Survey detection capabilities
Euclid preparation LXXIX. Using mock low surface brightness dwarf galaxies to probe Euclid Wide Survey detection capabilities Open
Local Universe dwarf galaxies can serve as both cosmological and mass assembly probes. Deep surveys have enabled the study of these objects down to the low surface brightness (LSB) regime. In this paper, we estimate Euclid's dwarf detectio…
View article: Euclid Quick Data Release (Q1). First Euclid statistical study of galaxy mergers and their connection to active galactic nuclei
Euclid Quick Data Release (Q1). First Euclid statistical study of galaxy mergers and their connection to active galactic nuclei Open
Galaxy major mergers are indicated as one of the principal pathways to trigger active galactic nuclei (AGN). We present the first statistical analysis of the major merger and AGN connection in the Euclid Deep Fields, and showcase the stati…
View article: How to prepare competitive proposals and job applications
How to prepare competitive proposals and job applications Open
View article: <i>Euclid</i>: Early Release Observations – The surface brightness and colour profiles of the far outskirts of galaxies in the Perseus cluster
<i>Euclid</i>: Early Release Observations – The surface brightness and colour profiles of the far outskirts of galaxies in the Perseus cluster Open
The Perseus field captured by Euclid as part of its Early Release Observations provides a unique opportunity to study cluster environment ranging from outskirts to dense regions. Leveraging unprecedented optical and near-infrared depths, w…
View article: The Complete <i>Spitzer</i> Survey of Stellar Structure in Galaxies (CS<sup>4</sup>G)
The Complete <i>Spitzer</i> Survey of Stellar Structure in Galaxies (CS<sup>4</sup>G) Open
Context. The Spitzer Survey of Stellar Structure in Galaxies (S 4 G), together with its Early Type Galaxy (ETG) extension, stands as the most extensive dataset of deep uniform mid-infrared (mid-IR; 3.6 and 4.5 μm) imaging for a sample of 2…
View article: <i>Euclid</i>: Early Release Observations – Programme overview and pipeline for compact- and diffuse-emission photometry
<i>Euclid</i>: Early Release Observations – Programme overview and pipeline for compact- and diffuse-emission photometry Open
The Euclid Early Release Observations (ERO) showcase Euclid ’s capabilities in advance of its main mission by targeting 17 astronomical objects, including galaxy clusters, nearby galaxies, globular clusters, and star-forming regions. A tot…
View article: Testing disc reprocessing models for AGN optical variability by comparison of X-ray and optical power spectra of NGC 4395
Testing disc reprocessing models for AGN optical variability by comparison of X-ray and optical power spectra of NGC 4395 Open
It is generally thought that AGN optical variability is produced, at least in part, by reprocessing of central X-rays by a surrounding accretion disc, resulting in wavelength-dependent lags between bands. Any good model of AGN optical vari…
View article: <i>Euclid</i> preparation
<i>Euclid</i> preparation Open
Extragalactic globular clusters (EGCs) are an abundant and powerful tracer of galaxy dynamics and formation, and their own formation and evolution is also a matter of extensive debate. The compact nature of globular clusters means that the…
View article: Gas flows in the central region of the Seyfert galaxy NGC 4593 with MUSE
Gas flows in the central region of the Seyfert galaxy NGC 4593 with MUSE Open
Understanding how gas flows into galactic centres, fuels the AGN, and is in turn expelled back through feedback processes is of great importance to appreciate the role AGN play in the growth and evolution of galaxies. We use the MUSE-AO op…
View article: <i>Euclid</i>: Early Release Observations – Globular clusters in the Fornax galaxy cluster, from dwarf galaxies to the intracluster field
<i>Euclid</i>: Early Release Observations – Globular clusters in the Fornax galaxy cluster, from dwarf galaxies to the intracluster field Open
We present an analysis of Euclid observations of a 0.6 deg 2 field in the central region of the Fornax galaxy cluster that were acquired during the performance verification phase. With these data, we investigated the potential of Euclid to…
View article: Gas flows in the central region of the Seyfert galaxy NGC 4593 with MUSE
Gas flows in the central region of the Seyfert galaxy NGC 4593 with MUSE Open
Context. Understanding how gas flows into galactic centres, fuels the active galactic nucleus (AGN), and is in turn expelled back through feedback processes is of great importance to appreciate the role AGN play in the growth and evolution…
View article: <i>Euclid</i> preparation
<i>Euclid</i> preparation Open
The Euclid mission is expected to image millions of galaxies at high resolution, providing an extensive dataset with which to study galaxy evolution. Because galaxy morphology is both a fundamental parameter and one that is hard to determi…
View article: Deriving the star formation histories of galaxies from spectra with simulation-based inference
Deriving the star formation histories of galaxies from spectra with simulation-based inference Open
High-resolution galaxy spectra encode information about the stellar populations within galaxies. The properties of the stars, such as their ages, masses, and metallicities, provide insights into the underlying physical processes that drive…
View article: Deriving the star formation histories of galaxies from spectra with simulation-based inference
Deriving the star formation histories of galaxies from spectra with simulation-based inference Open
High-resolution galaxy spectra encode information about the stellar populations within galaxies. The properties of the stars, such as their ages, masses, and metallicities, provide insights into the underlying physical processes that drive…
View article: Retrieval of the physical parameters of galaxies from WEAVE-StePS-like data using machine learning
Retrieval of the physical parameters of galaxies from WEAVE-StePS-like data using machine learning Open
Context. The William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) is a new, massively multiplexing spectrograph that allows us to collect about one thousand spectra over a 3 square degree field in one observation. The WEAVE S…
View article: Euclid preparation. LVIII. Detecting globular clusters in the Euclid survey
Euclid preparation. LVIII. Detecting globular clusters in the Euclid survey Open
Extragalactic globular clusters (EGCs) are an abundant and powerful tracer of galaxy dynamics and formation, and their own formation and evolution is also a matter of extensive debate. The compact nature of globular clusters means that the…
View article: Detection of an intranight optical hard-lag with colour variability in blazar PKS 0735+178
Detection of an intranight optical hard-lag with colour variability in blazar PKS 0735+178 Open
Blazars are a highly variable subclass of active galactic nuclei that have been observed to vary significantly during a single night. This intranight variability remains a debated phenomenon, with various mechanisms proposed to explain the…
View article: Gnuastro: Estimating the Zero-point Magnitude in Astronomical Imaging
Gnuastro: Estimating the Zero-point Magnitude in Astronomical Imaging Open
Calibration of pixel values is a fundamental step for accurate measurements in astronomical imaging. In astronomical jargon this is known as estimating zero-point magnitude. Here, we introduce a newly added script in GNU Astronomy Utilitie…
View article: Bar Properties as a Function of Wavelength: A Local Baseline with S4G for High-Redshift Studies
Bar Properties as a Function of Wavelength: A Local Baseline with S4G for High-Redshift Studies Open
The redshift evolution of bars is an important signpost of the dynamic maturity of disk galaxies. To characterize the intrinsic evolution safe from band-shifting effects, it is necessary to gauge how bar properties vary locally as a functi…
View article: Gnuastro: Estimating the Zero Point Magnitude in Astronomical Imaging
Gnuastro: Estimating the Zero Point Magnitude in Astronomical Imaging Open
Calibration of pixel values is a fundamental step for accurate measurements in astronomical imaging. In astronomical jargon this is known as estimating zero point magnitude. Here, we introduce a newly added script in GNU Astronomy Utilitie…
View article: Data supplement for paper on Gnuastro's zero point measurement script
Data supplement for paper on Gnuastro's zero point measurement script Open
Data supplements to the paper titled "Gnuastro: Estimating the Zero Point Magnitude in Astronomical Imaging", published in Research Notes of the American Astronomical Society (RNAAS) journal (arXiv:2312.04263). This paper introduces a rece…
View article: Data supplement for paper on Gnuastro's zero point measurement script
Data supplement for paper on Gnuastro's zero point measurement script Open
Data supplements to the paper titled "Gnuastro: Estimating the Zero Point Magnitude in Astronomical Imaging", published in Research Notes of the American Astronomical Society (RNAAS) journal (arXiv:2312.04263). This paper introduces a rece…
View article: Constraining the top-light initial mass function in the extended ultraviolet disk of M83
Constraining the top-light initial mass function in the extended ultraviolet disk of M83 Open
The universality or non-universality of the initial mass function (IMF) has significant implications for determining star formation rates and star formation histories from photometric properties of stellar populations. We reexamine whether…
View article: A giant thin stellar stream in the Coma Galaxy Cluster
A giant thin stellar stream in the Coma Galaxy Cluster Open
The study of dynamically cold stellar streams reveals information about the gravitational potential where they reside and provides important constraints on the properties of dark matter. However, the intrinsic faintness of these streams ma…
View article: Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS
Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS Open
The upcoming generation of optical spectrographs on four meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide high-quality spectra for thousan…
View article: Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS
Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS Open
Context. The upcoming generation of optical spectrographs on four meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide high-quality spectra fo…