arXiv subjects

Luka Matijević

Publications and source records attributed to Luka Matijević.

3 recordsLinked to original sources

arXiv2026

With arms wide open: a VLT/MUSE view of the mechanisms driving unwinding spiral arms in cluster galaxies

The environmental mechanisms driving unwinding spiral arms in cluster galaxies remain debated. While earlier studies attributed it mainly to gravitational interactions, recent works suggest that RPS alone can induce unwinding. We present a VLT/MUSE spatially resolved analysis to investigate the mechanisms responsible for spiral-arm unwinding in two galaxies, UG101 and UG103, drawn from a larger sample. They are selected as tidal and RPS-driven candidates, respectively, based on the proximity of close neighbors. We estimate the galactocentric radius at which tidal forces, from a companion or the cluster potential, become relevant ($R_{\mathrm{tid}}$). We examine gas and stellar kinematics, exploiting their different responses to gravitational and hydrodynamical perturbations. SINOPSIS is used to map stellar populations in age bins and constrain unwinding timescales. For UG101, we find $R_{\mathrm{tid}} \sim 1.5 R_e$, while the unwound features extend beyond this radius. UG101 shows irregular stellar and gas kinematics; its rotation curve indicates similar motions, although the gas is truncated on one side and extended on the other. For UG103, neither the closest companion nor the cluster appear capable of triggering unwinding. UG103 displays regular stellar but disturbed gas kinematics, with truncation on the disk side likely facing the ICM wind and gas extended in the opposite direction. Stellar population maps show the emergence and unwinding of the spiral arms in UG103 on timescales consistent with its cluster infall time ($\sim 1.6$ Gyr). We conclude that unwinding in UG101 and UG103 is primarily driven by tidal interactions and RPS, respectively, although a combined effect cannot be excluded for UG101. Our methodology provides a framework to identify the mechanisms driving unwinding in cluster galaxies from spatially resolved properties.

astro-ph.GA↗

arXiv2026

Motion Compensation for Real Time Ultrasound Scanning in Robotically Assisted Prostate Biopsy Procedures

Prostate cancer is one of the most common types of cancer in men. Its diagnosis by biopsy requires a high level of expertise and precision from the surgeon, so the results are highly operator-dependent. The aim of this work is to develop a robotic system for assisted ultrasound (US) examination of the prostate, a prebiopsy step that could reduce the dexterity requirements and enable faster, more accurate and more available prostate biopsy. We developed and validated a laboratory setup with a collaborative robotic arm that can autonomously scan a prostate phantom and attached the phantom to a medical robotic arm that mimics the patient's movements. The scanning robot keeps the relative position of the US probe and the prostate constant, ensuring a consistent and robust approach to reconstructing the prostate. To reconstruct the prostate, each slice is segmented to generate a series of prostate contours converted into a 3D point cloud used for biopsy planning. The average scan time of the prostate was 30 s, and the average 3D reconstruction of the prostate took 3 s. We performed four motion scenarios: the phantom was scanned in a stationary state (S), with horizontal motion (H), with vertical motion (V), and with a combination of the two (C). System validation is performed by registering the prostate point cloud reconstructions acquired during different motions (H, V, C) with those obtained in the stationary state. ICP registration with a threshold of 0.8 mm yields mean 83.2\% fitness and 0.35 mm RMSE for S-H registration, 84.1\% fitness and 0.37 mm RMSE for S-V registration and 79.4\% fitness and 0.37 mm RMSE for S-C registration. Due to the elastic and soft material properties of the prostate phantom, the maximum robot tracking error was 3 mm, which can be sufficient for prostate biopsy according to medical literature. The maximum delay in motion compensation was 0.5 s.

cs.RO↗

arXiv2025

The Competing Influence of Ram Pressure and Tidal Interaction in NGC 2276

The evolution of galaxies in groups is profoundly influenced by a variety of physical processes, with ram pressure and tidal interactions playing pivotal roles in shaping their structural and evolutionary pathways. The relative influence of these two processes is still debated in groups compared to clusters, as ram pressure is less understood there. We study NGC 2276, a nearby galaxy (z$\sim$0.0079) where the dominant process is still an open question. We examine the distribution of stellar populations in NGC 2276 using multiwavelength data to assess potential evidence of tidal interactions and ram-pressure stripping. We present the first HST WFC3/UVIS images of NGC 2276, and use them to investigate the distribution of stellar populations across the disk of NGC 2276, where we assume that the bluer broadband filters mainly trace younger stellar populations, while the redder filters trace mainly older stellar populations. Furthermore, by comparing HST images with maps of H$α$ emission from Calar Alto's PMAS/PPAK integral field unit (IFU) and near-IR maps from Spitzer's IRAC, we identify arm-like overdensity features that trace the spiral structure of this galaxy and tracked the variation of their pitch angle with radius. Our results indicate that the distribution of the stellar populations is asymmetrical. The youngest stellar populations (up to $\sim$100 Myr) show higher concentration on the leading side of the galaxy and are more diffuse on the trailing side, consistent with gas compression due to ram-pressure. This asymmetry is visible in the red filters as well. We also show that the average pitch angles of the overdensity features increase with galactocentric distance. Our findings are consistent with the fact that ram pressure is the leading mechanism for the peculiar morphology of NGC 2276, but do not exclude the possibility that tidal interactions could have played a role.

astro-ph.GA↗