Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2510.21921

The velocity dispersion profile of nine open clusters in the solar neighborhood

Bingqian Ma·XiaoYing Pang·Sambaran Banerjee·Pengfei Ren·M. B. N. Kouwenhoven
View original source ↗Read source document ↗Export metadata ↓

Abstract

We analyze the velocity dispersion profiles of nine open clusters in the solar neighborhood using kinematic data from Gaia DR 3, aiming to identify potential dynamical signatures of stellar-mass black holes through a comparison of theoretical and observed dispersion profiles. The selected clusters include LP2373 gp4, NGC 1980, NGC 2451A, NGC 2516, NGC 3532, NGC 6475, UBC 7, Praesepe, and Pleiades. We refine the center positions of the clusters with the Meanshift algorithm. Using the Markov Chain Monte Carlo method, we calculate the velocity dispersion for each cluster and construct one-dimensional velocity dispersion profiles. NGC 2516, NGC 3532, and NGC 6475 show potential central cusps in their radial velocity dispersion profiles, which may indicate the presence of stellar-mass black holes. LP2373 gp4, NGC 6475, and Praesepe all display a negative correlation between velocity dispersion and stellar mass, indicating these clusters are approaching energy equipartition or expanding. NGC 2516 and NGC 3532 exhibit a positive dependence between velocity dispersion and stellar mass, which may be attributed to the preferential ejection of massive stars following dynamical interactions involving binaries or black holes. These two clusters are the only two that are dynamical not relaxed and are closest to virial equilibrium. We compare the observations with N-body simulations of star clusters. A comparison of observed and simulated velocity dispersion profiles reveals that NGC 2516 and NGC 3532 exhibit lower proper motion dispersions than model clusters. Better agreement with the observed profiles is achieved for model clusters with larger ages. This suggests that the observed clusters may have undergone rapid dynamical evolution. Our results suggest that NGC 2516 and NGC 3532 may host at least two stellar-mass black holes each.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bingqian Ma, XiaoYing Pang, Sambaran Banerjee, Pengfei Ren, M. B. N. Kouwenhoven. 2025-10-24. The velocity dispersion profile of nine open clusters in the solar neighborhood. https://arxiv.org/abs/2510.21921

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

The Entangling of Supernova Feedback Impacts with Coarsening Simulation Resolution

It is often understood that supernova (SN) feedback in galaxies is responsible for regulating star formation (SF) and generating gaseous outflows. However, a detailed look at the small-scale effects of SNe on the interstellar medium (ISM) in simulations shows that the macroscopic processes of SF suppression and outflow generation proceed in distinct channels. We demonstrate this finding in two independent simulations of isolated dwarf galaxies with very high (m_gas ~ Msun) numerical resolution, LYRA and RIGEL. Our findings suggest that the macroscopic effect of a given SN on the galaxy is best predicted by its local density. Outflows are driven by SNe in diffuse regions expanding to their cooling radii on large (~kpc) scales, while dense SF regions are disrupted in a localized (~pc) manner. However, these separate feedback channels are only distinguishable at very high resolutions capable of following mass scales \lesssim 10^2 \msun. When averaging on coarser scales, ISM densities are greatly mis-estimated, and variations between different SF and SNe-affected regions are severely washed out. It therefore cannot be __self-consistently__ determined, from coarse-resolution information __alone__, (1) whether a SN tends to contribute to outflows or direct SF suppression, and (2) the rate of SF in a given region. In particular, commonly used parameters in coarse-resolution (subgrid) models, such as the SN cooling radius and SF density threshold, may require more detailed treatments informed by high-resolution studies.

astro-ph.GA↗
arXiv2026

Computational advances and challenges in simulations of turbulence and star formation

We review recent advances in the numerical modeling of turbulent flows and star formation. An overview of the most widely used simulation codes and their core capabilities is provided. We then examine methods for achieving the highest-resolution magnetohydrodynamical turbulence simulations to date, highlighting challenges related to numerical viscosity and resistivity. State-of-the-art approaches to modeling gravity and star formation are discussed in detail, including implementations of star particles and feedback from jets, winds, heating, ionization, and supernovae. We review the latest techniques for radiation hydrodynamics, including ray tracing, Monte Carlo, and moment methods, with comparisons between the flux-limited diffusion, moment-1, and variable Eddington tensor methods. The final chapter summarizes advances in cosmic-ray transport schemes, emphasizing their growing importance for connecting small-scale star formation physics with galaxy-scale evolution.

astro-ph.GA↗
arXiv2026

How significant is the lensing interpretation of GW231123?

GW231123 is one of the most unusual gravitational-wave (GW) events, with exceptionally large inferred masses and near-extremal spins, offering an opportunity to test whether propagation effects contribute to these properties. We therefore examine whether the data support wave-optics microlensing embedded in a strong-lensing galaxy, whose detection becomes increasingly likely as observations accumulate, whether this interpretation can explain these properties, and how significant the preference remains under detector noise and waveform systematics. We compare six hypotheses: unlensed, isolated point mass, and embedded point-mass (EPM) and binary-lens (EB) effective models in Type-I (minimum) and Type-II (saddle) macro images. The EB Type-I model is most favored. For the most accurate waveform model NRSur7dq4, it gives $\log_{10}B^{\rm EB-I}_{\rm U}=2.60$, versus $0.89$ for Type II, indicating sensitivity to macro-image geometry. Within Type I, however, the binary improves over the point mass by only $\log_{10}B^{\rm EB-I}_{\rm EPM-I}=0.16$ and $Δ\ln\mathcal{L}_{\max}=0.56$, providing no clear evidence for structure beyond a single effective perturber. Moreover, under embedded lensing, waveform-template discrepancies and inferred masses and spins are reduced. However, real O4a backgrounds from numerical-relativity injections show that the apparent lensing evidence is sensitive to waveform systematics and realistic detector noise: although the commonly used waveform IMRPhenomXPHM gives the largest Bayes factor, $\log_{10}B^{\rm EB-I}_{\rm U}=4.52$, it is less exceptional relative to its own background, with a false-alarm probability of $6.5$--$8\%$, whereas NRSur7dq4 gives only $2$--$3\%$. Thus, waveform systematics can amplify apparent lensing evidence, but GW231123 remains an intriguing lensing candidate.

astro-ph.GA↗