arXiv subjects

D. Krajnović

Publications and source records attributed to D. Krajnović.

10 recordsLinked to original sources

arXiv2026

MUSE-DARK IV. Comparing Dark Matter Densities to Star Formation Histories in 375 intermediate-z galaxies

(Abridged) Baryonic feedback is expected to transform cuspy dark-matter (DM) haloes into cores, but direct observational links between inner DM slopes and galaxy star-formation histories (SFHs) remain limited. We investigate and quantify the connection between halo inner slopes and baryonic assembly histories in a large sample of intermediate-z galaxies. We analyse 375 galaxies at 0.1<z<1.43 spanning 7<log(Mstar/Msun)<11.2 using 3D forward modelling of MUSE kinematics and disk-halo decompositions with mass-dependent (DC14-based) and generalised Navarro-Frenk-White (gNFW) halo profiles. Stellar population parameters are inferred from multi-band Spectral Energy Distribution fitting of UV-to-MIR photometry using a non-parametric SFH model. Bayesian model comparison shows that the DC14-based halo density profiles are statistically preferred over gNFW for a substantial fraction of the sample. The inferred inner slopes from gNFW fits nevertheless follow the DC14 expectation and reproduce the expected dependence on the stellar-to-halo mass ratio, despite this not being explicitly imposed. Partial correlation coefficient and random forest regression analyses consistently identify stellar mass (or, equivalently, the stellar-to-halo mass ratio) as the primary driver of the inner density slope, a result that holds robustly even when the analysis is restricted to the gNFW fits. In contrast, SFH-related quantities (e.g. formation time and 'burstiness' indicators) exhibit no independent predictive power on the DM halo inner slope once the dependence on stellar mass is accounted for. Cored systems preferentially occupy lower-mass, more bursty bins with later assembly times, whereas cuspy systems are associated with higher stellar masses, lower star formation activity, and earlier assembly epochs, in agreement with theoretical expectations of stellar-feedback-induced cores.

astro-ph.GA↗

arXiv2026

MUSE-DARK III: The evolution of the radial acceleration relation at intermediate redshifts

The radial acceleration relation (RAR) is a tight empirical correlation between the observed radial acceleration (a_tot) and the baryonic radial acceleration (a_bar) measured across galaxy radii: these two accelerations start to deviate significantly from each other below a characteristic acceleration scale, a0. So far, observational studies of the RAR have predominantly focused on galaxies in the local Universe, leaving its evolution with cosmic time largely unexplored. Using high signal-to-noise data from the MUSE Hubble Ultra Deep Field survey, we investigate the RAR with a sample of 79 star-forming galaxies (complete above M* >10^8.8 Msun) at intermediate redshifts (0.33 <z <1.44). We estimate the observed intrinsic acceleration and the baryonic acceleration from a disk-halo decomposition that incorporates stellar, gas, and dark matter components, with corrections for pressure support, using 3D forward modelling. We find a RAR in our intermediate-z sample offset from the local relation, with a higher characteristic acceleration scale, a0(z~1) = 2.38+/-0.1* 10^-10 m/s^2, and a larger intrinsic scatter (~0.17 dex). Dividing the sample into redshift bins and refitting the RAR in each bin, we find a characteristic acceleration scale that systematically increases with z. Parametrizing the z-dependence as a0(z)= a0(0) + a1 * z, we obtain a1 = 1.59+/-0.1 *10^-10 m/s^2, providing evidence for a z-evolution. We find similar results using various dark matter halo profiles as well as the Modified Newtonian Dynamics framework in our 3D forward modelling. Our results show that the RAR persists at intermediate redshift, with statistically significant redshift evolution of the characteristic acceleration, pointing to a possible evolution of the baryon-missing mass connection over cosmic time.

astro-ph.GA↗

arXiv2026

MUSE-DARK-I: Dark matter halo properties of intermediate-z star-forming galaxies

[Abridged] We analyse the dark matter (DM) halo properties of 127 0.3 80% of the sample. We find that the kinematically inferred stellar masses agree with values from SED fitting. We find that 89% of galaxies have DM fractions >50%. For 66% of SFGs, we infer a DM inner slope, gamma < 0.5, indicating cored DM profiles, but no correlation is found between gamma and star formation rate of the sample. The stellar- and concentration-mass relations agree with theoretical expectations, but with larger scatter. We confirm the anticorrelation between halo scale radius and DM density. The halo scale radii and DM surface densities increase with Mstar, while DM densities stay constant. We find tentative evidence of an evolution of the DM density with z, which suggests that the DM halos of intermediate-z systems are denser than those of local galaxies. In contrast, the halo scale radii are z-invariant.

astro-ph.GA↗

arXiv2023

Stellar angular momentum of disk galaxies at z = 0.7 in the MAGIC survey I. Impact of the environment

Aims: At intermediate redshift, galaxy groups/clusters are thought to impact galaxies (e.g. their angular momentum). We investigate whether the environment has an impact on the galaxies' angular momentum and identify underlying driving physical mechanisms. Methods: We derive robust estimates of the stellar angular momentum using Hubble Space Telescope (HST) images combined with spatially resolved ionised gas kinematics from the Multi-Unit Spectroscopic Explorer (MUSE) for a sample of ~200 galaxies in groups and in the field at z~0.7 drawn from the MAGIC survey. Using various environmental tracers, we study the position of the galaxies in the the angular momentum-stellar mass (Fall) relation as a function of environment. Results: We measure a 0.12 dex (2sigma significant) depletion of angular momentum for low-mass galaxies (M* < 10^10 Msun) in groups with respect to the field. Massive galaxies located in dense environments have less angular momentum than expected from the low-mass Fall relation but, without a comparable field sample, we cannot infer whether this effect is mass- or environmentally-driven. Furthermore, massive galaxies are found in the centre of the structures and have low systemic velocities. The observed depletion of angular momentum at low mass does not appear linked with the strength of the over-density around the galaxies but it is strongly correlated with the galaxies' systemic velocity normalised by the dispersion of their host group and with their ionised gas velocity dispersion. Conclusions: Group galaxies seem depleted in angular momentum, especially at low mass. Our results suggest that this depletion might be induced by physical mechanisms that scale with the systemic velocity of the galaxies (e.g. stripping or merging) and that such mechanism might be responsible for enhancing the velocity dispersion of the gas as galaxies lose angular momentum.

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arXiv2022

Scaling relations of z~0.25-1.5 galaxies in various environments from the morpho-kinematic analysis of the MAGIC sample

The evolution of galaxies is influenced by many physical processes which may vary depending on their environment. We combine Hubble Space Telescope (HST) and Multi-Unit Spectroscopic Explorer (MUSE) data of galaxies at 0.25<z<1.5 to probe the impact of environment on the size-mass relation, the Main Sequence (MS) and the Tully-Fisher relation (TFR). We perform a morpho-kinematic modelling of 593 [Oii] emitters in various environments in the COSMOS area from the MUSE-gAlaxy Groups In Cosmos (MAGIC) survey. The HST F814W images are modelled with a bulge-disk decomposition to estimate their bulge-disk ratio, effective radius and disk inclination. We use the [Oii]λλ3727, 3729 doublet to extract the ionised gas kinematic maps from the MUSE cubes, and we model them for a sample of 146 [Oii] emitters, with bulge and disk components constrained from morphology and a dark matter halo. We find an offset of 0.03 dex on the size-mass relation zero point between the field and the large structure subsamples, with a richness threshold of N=10 to separate between small and large structures, and of 0.06 dex with N=20. Similarly, we find a 0.1 dex difference on the MS with N=10 and 0.15 dex with N=20. These results suggest that galaxies in massive structures are smaller by 14% and have star formation rates reduced by a factor of 1.3-1.5 with respect to field galaxies at z=0.7. Finally, we do not find any impact of the environment on the TFR, except when using N=20 with an offset of 0.04 dex. We discard the effect of quenching for the largest structures that would lead to an offset in the opposite direction. We find that, at z=0.7, if quenching impacts the mass budget of galaxies in structures, these galaxies would have been affected quite recently, for roughly 0.7-1.5 Gyr. This result holds when including the gas mass, but vanishes once we include the asymmetric drift correction.

astro-ph.GA↗

arXiv2020

Optical emission lines in the most massive galaxies: morphology, kinematics and ionisation properties

To better characterize the upper end of the galaxy stellar mass range, the MUSE Most Massive Galaxies (M3G) Survey targeted the most massive galaxies (M$>10^{12}$ M$_{\odot}$) found in the densest known clusters of galaxies at $z\sim0.046$. The sample is composed by 25 early-type galaxies: 14 BCGs, of which 3 are in the densest region of the Shapley Super Cluster (SSC), and 11 massive satellites in the SSC. In this work we aim at deriving the spatial distribution and kinematics of the gas, and discussing its ionisation mechanism and origin in the optical wavelength range with MUSE data. We fit the continuum of the spectra using an extensive library of single stellar population models and model the emission lines employing up to three Gaussian functions. In the M3G sample, ionized-gas was detected in 5 BCGs, of which one is in the densest region of the SSC, and 6 massive satellites in the SSC. Among these objects, [OI] and [NI] were detected in 3 BCGs and one satellite. The gas is centrally concentrated in almost all objects, except for 2 BCGs that show filaments and 2 massive satellites with extended emission. The emission line profiles of 3 BCGs present red/blueshifted components. The presence of dust was revealed by analysing Balmer line ratios obtaining a mean $E(B-V)$ of 0.2-0.3. The emission-line diagnostic diagrams show predominately LINER line ratios with little contamination from star formation. The gas was detected in 80% of fast rotators and 35% of slow rotators. The orientations of stellar and gaseous rotations are aligned with respect to each other for 60% of satellites and 25% of BCGs. The presence of misalignments points to an external origin of the gas for 3 BCGs and 2 satellites. On the other hand, some of these systems are characterized by triaxial and prolate-like stellar rotation that could support an internal origin of the gas even in case of misalignments.

astro-ph.GA↗

arXiv2019

The MUSE-Wide Survey: Survey Description and First Data Release

We present the MUSE-Wide survey, a blind, 3D spectroscopic survey in the CANDELS/GOODS-S and CANDELS/COSMOS regions. Each MUSE-Wide pointing has a depth of 1 hour and hence targets more extreme and more luminous objects over 10 times the area of the MUSE-Deep fields (Bacon et al. 2017). The legacy value of MUSE-Wide lies in providing "spectroscopy of everything" without photometric pre-selection. We describe the data reduction, post-processing and PSF characterization of the first 44 CANDELS/GOODS-S MUSE-Wide pointings released with this publication. Using a 3D matched filtering approach we detected 1,602 emission line sources, including 479 Lyman-$α$ (Lya) emitting galaxies with redshifts $2.9 \lesssim z \lesssim 6.3$. We cross-match the emission line sources to existing photometric catalogs, finding almost complete agreement in redshifts and stellar masses for our low redshift (z < 1.5) emitters. At high redshift, we only find ~55% matches to photometric catalogs. We encounter a higher outlier rate and a systematic offset of $Δ$z$\simeq$0.2 when comparing our MUSE redshifts with photometric redshifts. Cross-matching the emission line sources with X-ray catalogs from the Chandra Deep Field South, we find 127 matches, including 10 objects with no prior spectroscopic identification. Stacking X-ray images centered on our Lya emitters yielded no signal; the Lya population is not dominated by even low luminosity AGN. A total of 9,205 photometrically selected objects from the CANDELS survey lie in the MUSE-Wide footprint, which we provide optimally extracted 1D spectra of. We are able to determine the spectroscopic redshift of 98% of 772 photometrically selected galaxies brighter than 24th F775W magnitude. All the data in the first data release - datacubes, catalogs, extracted spectra, maps - are available on the website https://musewide.aip.de. [abridged]

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arXiv2016

Deep MUSE observations in the HDFS. Morpho-kinematics of distant star-forming galaxies down to $10^8$M$_\odot$

(Abridged) We make use of the deepest VLT/MUSE observations performed so far on the Hubble Deep Field South (HDFS) to characterize the low-mass (< $10^{10}$M$_\odot$) galaxy population at intermediate redshift. We identify a sample of 28 spatially-resolved emission-line galaxies in the deep (27h integration time) MUSE data cube, spread over a redshift interval of 0.2 < z < 1.4. The public HST images and multi-band photometry over the HDFS are used to constrain the stellar mass and star formation rate (SFR) of the galaxies and to perform a morphological analysis. We derive the resolved ionized gas properties of these galaxies from the MUSE data and model the disk (both in 2D and with GalPaK$^{\rm 3D}$) to retrieve their intrinsic gas kinematics. We build a sample of resolved emission-line galaxies of much lower stellar mass and SFR (by $\sim$1-2 orders of magnitude) than previous 3D spectroscopic surveys. Most of the spatially-resolved MUSE-HDFS galaxies have gas kinematics consistent with disk-like rotation, but about 20% have velocity dispersions larger than the rotation velocities, and 30% are part of a close pair and/or show clear signs of recent gravitational interactions. In the high-mass regime, the MUSE-HDFS galaxies follow the Tully-Fisher relation defined from previous surveys in a similar redshift range. This scaling relation extends also to lower masses/velocities but with a higher dispersion. The MUSE-HDFS galaxies follow the scaling relations defined in the local universe between the specific angular momentum and the stellar mass. However, we find that intermediate-redshift star-forming galaxies fill a continuum transition from the spiral to elliptical local scaling relations, according to the dynamical state of the gas. This indicates that some galaxies may lose their angular momentum and become dispersion-dominated prior to becoming passive.

astro-ph.GA↗

arXiv2016

The low dark matter content of the lenticular galaxy NGC 3998

We observed the lenticular galaxy NGC 3998 with the Mitchell Integral-Field Spectrograph and extracted line-of-sight velocity distributions out to 3 half-light radii. We constructed collisionless orbit models in order to constrain NGC 3998's dark and visible structure, using kinematics from both the Mitchell and SAURON instruments. We find NGC 3998 to be almost axisymmetric, seen nearly face on with a flattened intrinsic shape - i.e., a face-on fast-rotator. We find an I-band mass-to-light ratio of $4.7_{-0.45}^{+0.32}$ in good agreement with previous spectral fitting results for this galaxy. Our best-fit orbit model shows a both a bulge and a disc component, with a non-negligible counter-rotating component also evident. We find that relatively little dark matter is needed to model this galaxy, with an inferred dark mass fraction of just $(7.1^{+8.1}_{-7.1})\%$ within one half-light radius.

astro-ph.GA↗

arXiv2011

The SAURON Project - XIX. Optical and near-infrared scaling relations of nearby elliptical, lenticular and Sa galaxies

[Abridged] We present ground-based MDM V-band and Spitzer/IRAC 3.6um-band photometric observations of the 72 representative galaxies of the SAURON Survey. In combination with the SAURON stellar velocity dispersion measured within an effective radius (se), this allows us to explore the location of our galaxies in the main scaling relations. We investigate the dependence of these relations on our recent kinematical classification of early-type galaxies (i.e. Slow/Fast Rotators) and the stellar populations. Slow Rotator and Fast Rotator E/S0 galaxies do not populate distinct locations in the scaling relations, although Slow Rotators display a smaller intrinsic scatter. Surprisingly, extremely young objects do not display the bluest (V-[3.6]) colours in our sample, as is usually the case in optical colours. This can be understood in the context of the large contribution of TP-AGB stars to the infrared, even for young populations, resulting in a very tight (V-[3.6]) - se relation that in turn allows us to define a strong correlation between metallicity and velocity dispersion. Many Sa galaxies appear to follow the Fundamental Plane defined by E/S0 galaxies. Galaxies that appear offset from the relations correspond mostly to objects with extremely young populations, with signs of on-going, extended star formation. We correct for this effect in the Fundamental Plane, by replacing luminosity with stellar mass using an estimate of the stellar mass-to-light ratio, so that all galaxies are part of a tight, single relation. The new estimated coefficients are consistent in both photometric bands and suggest that differences in stellar populations account for about half of the observed tilt with respect to the virial prediction. After these corrections, the Slow Rotator family shows almost no intrinsic scatter around the best-fit Fundamental Plane.

astro-ph.CO↗