ORCID Profile
0000-0002-2380-9801
Current Organisations
ISAR Bioscience Institute
,
Julius-Maximilians-Universität Würzburg
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: American Astronomical Society
Date: 28-05-2021
Abstract: We explore the connection between the kinematics, structures and stellar populations of massive galaxies at 0.6 z 1.0 using the fundamental plane (FP). Combining stellar kinematic data from the Large Early Galaxy Astrophysics Census (LEGA-C) survey with structural parameters measured from deep Hubble Space Telescope imaging, we obtain a s le of 1419 massive ( log ( M * / M ⊙ ) 10.5 ) galaxies that span a wide range in morphology, star formation activity, and environment, and therefore is representative of the massive galaxy population at z ∼ 0.8. We find that quiescent and star-forming galaxies occupy the parameter space of the g -band FP differently and thus have different distributions in the dynamical mass-to-light ratio ( M dyn / L g ), largely owing to differences in the stellar age and recent star formation history, and to a lesser extent, the effects of dust attenuation. In contrast, we show that both star-forming and quiescent galaxies lie on the same mass FP at z ∼ 0.8, with a comparable level of intrinsic scatter about the plane. We examine the variation in M dyn / M * through the thickness of the mass FP, finding no significant residual correlations with stellar population properties, Sérsic index, or galaxy overdensity. Our results suggest that, at fixed size and velocity dispersion, the variations in M dyn / L g of massive galaxies reflect an approximately equal contribution of variations in M * / L g , and variations in the dark matter fraction or initial mass function.
Publisher: American Astronomical Society
Date: 07-2023
Abstract: We present JWST NIRCam nine-band near-infrared imaging of the luminous z = 10.6 galaxy GN-z11 from the JWST Advanced Deep Extragalactic Survey of the GOODS-N field. We find a spectral energy distribution (SED) entirely consistent with the expected form of a high-redshift galaxy: a clear blue continuum from 1.5 to 4 μ m with a complete dropout in F115W. The core of GN-z11 is extremely compact in JWST imaging. We analyze the image with a two-component model, using a point source and a Sérsic profile that fits to a half-light radius of 200 pc and an index n = 0.9. We find a low-surface-brightness haze about 0.″4 to the northeast of the galaxy, which is most likely a foreground object but might be a more extended component of GN-z11. At a spectroscopic redshift of 10.60 (Bunker et al. 2023), the comparison of the NIRCam F410M and F444W images spans the Balmer jump. From population-synthesis modeling, here assuming no light from an active galactic nucleus, we reproduce the SED of GN-z11, finding a stellar mass of ∼10 9 M ⊙ , a star formation rate of ∼20 M ⊙ yr −1 , and a young stellar age of ∼20 Myr. Since massive galaxies at high redshift are likely to be highly clustered, we search for faint neighbors of GN-z11, finding nine galaxies out to ∼5 comoving Mpc transverse with photometric redshifts consistent with z = 10.6, and a tenth more tentative dropout only 3″ away. This is consistent with GN-z11 being hosted by a massive dark-matter halo (≈8 × 10 10 M ⊙ ), though lower halo masses cannot be ruled out.
Publisher: EDP Sciences
Date: 10-2202
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present spatially resolved stellar kinematics for 797 z = 0.6–1 galaxies selected from the LEGA-C survey and construct axisymmetric Jeans models to quantify their dynamical mass and degree of rotational support. The survey is K s -band selected, irrespective of color or morphological type, and allows for a first assessment of the stellar dynamical structure of the general L * galaxy population at large look-back time. Using light profiles from Hubble Space Telescope imaging as a tracer, our approach corrects for observational effects (seeing convolution and slit geometry), and uses well-informed priors on inclination, anisotropy, and a non-luminous mass component. Tabulated data include total mass estimates in a series of spherical apertures (1, 5, and 10 kpc 1 × and 2 × R e ), as well as rotational velocities, velocity dispersions, and anisotropy. We show that almost all star-forming galaxies and ∼50% of quiescent galaxies are rotation dominated, with deprojected V / σ ∼ 1–2. Revealing the complexity in galaxy evolution, we find that the most massive star-forming galaxies are among the most rotation dominated, and the most massive quiescent galaxies among the least rotation-dominated galaxies. These measurements set a new benchmark for studying galaxy evolution, using stellar dynamical structure for galaxies at large look-back time. Together with the additional information on stellar population properties from the LEGA-C spectra, the dynamical mass and V / σ measurements presented here create new avenues for studying galaxy evolution at large look-back time.
Publisher: Springer Science and Business Media LLC
Date: 04-04-2023
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: American Astronomical Society
Date: 26-10-2023
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: American Astronomical Society
Date: 06-11-2020
Publisher: Springer Science and Business Media LLC
Date: 19-07-2023
Publisher: Oxford University Press (OUP)
Date: 16-03-2022
Abstract: We investigate changes in stellar population age and metallicity ([Z/H]) scaling relations for quiescent galaxies from intermediate redshift (0.60 ≤ $z$ ≤ 0.76) using the LEGA-C Survey to low redshift (0.014 ≤ $z$ ≤ 0.10) using the SAMI Galaxy Survey. Specifically, we study how the spatially integrated global age and metallicity of in idual quiescent galaxies vary in the mass–size plane, using the stellar mass M* and a dynamical mass proxy derived from the virial theorem MD ∝ σ2 Re. We find that, similarly to at low redshift, the metallicity of quiescent galaxies at 0.60 ≤ $z$ ≤ 0.76 closely correlates with M/Re (a proxy for the gravitational potential or escape velocity), in that galaxies with deeper potential wells are more metal-rich. This supports the hypothesis that the relation arises due to the gravitational potential regulating the retention of metals by determining the escape velocity for metal-rich stellar and supernova ejecta to escape the system and avoid being recycled into later stellar generations. Conversely, we find no correlation between age and surface density ($M/R_\\mathrm{e}^2$) at 0.60 ≤ $z$ ≤ 0.76, despite this relation being strong at low redshift. We consider this change in the age–$M/R_\\mathrm{e}^2$ relation in the context of the redshift evolution of the star-forming and quiescent mass–size relations, and find our results are consistent with galaxies forming more compactly at higher redshifts and remaining compact throughout their evolution. Furthermore, galaxies appear to quench at a characteristic surface density that decreases with decreasing redshift. The $z$ ∼ 0 age–$M/R_\\mathrm{e}^2$ relation is therefore a result of building up the quiescent and star-forming populations with galaxies that formed at a range of redshifts and therefore a range of surface densities.
Publisher: American Astronomical Society
Date: 08-2023
Abstract: In this empirical work, we aim to quantify the systematic uncertainties in stellar-mass ( M ⋆ ) estimates made from spectral energy distribution (SED) fitting through stellar population synthesis (SPS) for galaxies in the local Universe by using the dynamical mass ( M dyn ) estimator as an SED-independent check on stellar mass. We first construct a statistical model of the high-dimensional space of galaxy properties including size ( R e ), velocity dispersion ( σ e ), surface brightness ( I e ), mass-to-light ratio ( M ⋆ / L ), rest-frame color, Sérsic index ( n ), and dynamical mass ( M dyn ), and accounting for selection effects and covariant errors. We disentangle the correlations among galaxy properties and find that the variation in M ⋆ / M dyn is driven by σ e , Sérsic index and color. We use these parameters to calibrate an SED-independent M ⋆ estimator, M ˆ ⋆ . We find the random scatter of the relation M ⋆ − M ˆ ⋆ to be 0.108 dex and 0.147 dex for quiescent and star-forming galaxies, respectively. Finally, we inspect the residuals as a function of SPS parameters (dust, age, metallicity, and star formation rate) and spectral indices (H α , H δ , and D n 4000). For quiescent galaxies, ∼65% of the scatter can be explained by the uncertainty in SPS parameters, with dust and age being the largest sources of uncertainty. For star-forming galaxies, while age and metallicity are the leading factors, SPS parameters account for only ∼13% of the scatter. These results leave us with remaining unmodelled scatters of 0.055 dex and 0.122 dex for quiescent and star-forming galaxies, respectively. This can be interpreted as a conservative limit on the precision in M ⋆ that can be achieved via simple SPS modeling.
Publisher: Springer Science and Business Media LLC
Date: 04-04-2023
Publisher: Springer Science and Business Media LLC
Date: 15-06-2020
DOI: 10.1038/S41589-020-0566-1
Abstract: G-protein-coupled receptors (GPCRs) are key signaling proteins that mostly function as monomers, but for several receptors constitutive dimer formation has been described and in some cases is essential for function. Using single-molecule microscopy combined with super-resolution techniques on intact cells, we describe here a dynamic monomer-dimer equilibrium of µ-opioid receptors (µORs), where dimer formation is driven by specific agonists. The agonist DAMGO, but not morphine, induces dimer formation in a process that correlates both temporally and in its agonist- and phosphorylation-dependence with β-arrestin2 binding to the receptors. This dimerization is independent from, but may precede, µOR internalization. These data suggest a new level of GPCR regulation that links dimer formation to specific agonists and their downstream signals.
Location: Germany
Location: United Kingdom of Great Britain and Northern Ireland
Location: Germany
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Anna de Graaff.