Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.32537

The Galactic rotation curve from the ALS III catalogue of OB Stars

S. R. Berlanas·M. Pantaleoni González·J. Maíz Apellániz
View original source ↗Read source document ↗Export metadata ↓

Abstract

The Galactic rotation curve reveals the radial mass distribution of the Milky Way, but its determination depends on the tracer population. Young massive stars are the least dynamically evolved tracer, retaining the kinematics of the gas from which they formed, yet previous determinations from OB stars were confined to the solar neighbourhood. We determine the rotation curve and the solar motion from 14017 spectroscopically confirmed OB stars from the ALS III catalogue, using Gaia DR3 five-dimensional astrometry with revised distances and corrected proper motions. The curve is parameterised as a fourth-degree Chebyshev polynomial in Galactocentric radius and fitted to the proper motions by weighted least squares, solving simultaneously for the solar motion. Uncertainties are derived from 1000 bootstrap resamplings. We obtain a circular velocity at the solar radius (8.178 kpc) of 236.3 +/- 1.1 km/s, solar motion components U = 8.06 +/- 0.41, V = 10.91 +/- 0.86 and W = 7.53 +/- 0.14 km/s, and Oort constants A = 16.35 +/- 0.21 and B = -12.54 +/- 0.19 km/s/kpc. The curve rises inside the solar circle and declines gently beyond it, with a local gradient of -3.81 +/- 0.38 km/s/kpc, and is constrained between 5.5 and 11 kpc. Because the tracer is dynamically cold and the proper motions are fitted directly, no asymmetric drift correction or Jeans modelling is required, so the systematics differ from those affecting older tracers. The gentle decline beyond the solar radius agrees with determinations from older tracers where they overlap, making it unlikely to be a methodological artefact. Only the solar radial motion is poorly constrained by tangential data, without affecting the curve. The stars departing most from the curve (1474 to 1662, depending on the selection criterion) form the largest sample of OB runaway candidates to date, to be analysed in a forthcoming paper based on Gaia DR4.

Explore related subjects

astro-ph.GAastro-ph.SR

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S. R. Berlanas, M. Pantaleoni González, J. Maíz Apellániz. 2026-10-23. The Galactic rotation curve from the ALS III catalogue of OB Stars. https://arxiv.org/abs/2610.32537

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

KEEP EXPLORING

Related papers

arXiv2026

UCLCHEM 4.0: An open source gas-grain astrochemistry simulation framework

Astrochemical modelling is a key tool for interpreting the formation and destruction of molecules in the interstellar medium, complementing the increasingly detailed observations enabled by modern day observational facilities. UCLCHEM is a comprehensive gas-grain astrochemical modelling framework that can compute the chemical evolution inside a parcel of gas and dust under a specified, time-dependent physical description. This allows both the post-processing of hydrodynamical simulations and the usage of physical parametrizations, ranging in context from extra-galactic to protoplanetary disk scales. The framework consists of a core routine that solves gas-grain chemical reaction networks as a function of time, self-consistently coupled to either a user-defined or parametrized physical evolution of density, temperature and other physical input parameters. The chemistry is solved with a rate-equation formalism, and includes a three phase description, namely gas phase, ice surface and bulk ice. This includes transport between the gas and ice phases via freeze-out, thermal and non-thermal desorption mechanisms, as well as a geometrical treatment of the growth and shrinkage of the surface and bulk chemistry. The framework includes parametrizations for astrochemical modelling of cloud collapses, protostellar cores and shocks as well as the ability to provide user-defined inputs. This release of the framework focuses on many quality-of-life-improvements, including an object-oriented Python interface, an upgrade from two phase to three phases and expanded support for post-processing of hydrodynamical simulations and user-defined parametrizations. This manuscript provides an overview of the physics and chemistry included in UCLCHEM, as well as the inner workings of the solver routine and the programming interface.

astro-ph.GA↗
arXiv2026

Even central galaxies feel their environment: cosmic siphoning of cool gas accretion

Identifying the key processes regulating cool gas accretion in galaxies is essential for understanding the baryon cycle within galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction ($μ_{\rm HI} \equiv M_{\rm HI}/M_{\star} \propto M_{\rm BH}^{-0.6}$). Here we further explore the primary external effects on cool gas accretion in central galaxies. We find that galaxies deviating significantly from the $μ_{\rm HI}-M_{\rm BH}$ relation are overwhelmingly isolated central galaxies without substantial satellites. These isolated, gas-poor centrals exhibit systematically higher black-hole-to-stellar-mass ratios and more prominent bulges. At larger scales, they are preferentially located near massive neighboring halos. We suggest that this may reflect a ``cosmic siphoning" scenario, replenished by their satellites and by gas flowing along the cosmic web. This model naturally explains the prevalence of gas-poor isolated central galaxies near massive halos. It complements internal regulation by supermassive black holes and suggests a cosmic 'rich get richer' scenario.

astro-ph.GA↗
arXiv2026

Decoupling candidate dual AGN from chance superpositions in the GOTHIC survey via a deep-learning framework

Dual active galactic nuclei (DAGN) mark a critical phase in the evolution of merging galaxies and the pairing of supermassive black holes, yet they remain difficult to identify in large imaging surveys because of projection effects and limited spatial resolution. Compact foreground stars and unresolved substructure can mimic dual nuclei through chance superposition, complicating automated detection. We revisit the 46,061 galaxies flagged but rejected as DAGN candidates by the GOTHIC pipeline, primarily because the two nuclei fell within the SDSS fibre aperture or exceeded its separation threshold. We train a supervised deep-learning framework based on the YOLOv11 oriented-bounding-box architecture on annotated SDSS imaging to separate genuine dual nuclei from foreground stellar contaminants and other spurious alignments. The final model attains a validation precision of 0.919, recall of 0.905, and $F_1$ of 0.912, and yields 29,605 dual-nucleus candidates after removing star-dominated and blended detections. Structured visual inspection indicates that $54.5$--$62\%$ are consistent with genuine dual nuclei, implying $\sim(1.4$--$1.8)\times10^{4}$ plausible systems. Cross-calibrating the YOLO separation against the deterministic GOTHIC centroid measurement and restricting to the compact regime ($d \le 6.87''$) gives a conservative subset of $\sim 13{,}672$ candidates, reaching calibrated separations of $\sim 0.56''$. Spectroscopy of the most compact ($\le 1$ kpc) systems shows spectra dominated by stellar absorption, with no resolved double-peaked emission, so confirmation requires higher-resolution follow-up. The catalogue is a statistically refined list of candidates, not confirmed DAGN. Nonetheless, deep-learning detection substantially reduces contamination and expands the plausible DAGN census.

astro-ph.GA↗