Heavy interstellar scattering toward the near end of the Galactic bar

Abstract

We present results of a pilot observational wide-field VLBI campaign on probing scattering properties of the partly ionized interstellar medium towards the Galactic plane sky region between $28^{\circ }<l<36^{\circ }$ and $|b|<1^{\circ }$. This covers the region where the Galactic bar connects to the spiral arms and where a lot of star formation is currently ongoing. The Very Long Baseline Array (VLBA) observations of the whole region were performed in a special mode with multiple phase centers at L-band (1.4 -- 1.8 GHz) during April-June 2022 and a year later complemented by sessions at S (2.2 -- 2.4 GHz) and C-band (4.6 -- 5.0 GHz) partially covering the pilot region. We found compelling evidence that target sources are subject to scattering. The total detection rate in L, S and C-bands is 1.5, 3.4 and 9.2 per cent, respectively, and approximately scales with the square of the observation frequency. The low rate values imply that scattering is strong. Its power is non-uniform across the Galactic plane and it can be approximated by a Gaussian with a width of about $2^{\circ }$ peaking at the Galactic mid-plane. One of the brightest sources of the field shows anisotropic scattering, with a ${\lambda }^2$ dependence of its observed angular size, along a position angle of $26^{\circ }$ aligned with the line of constant Galactic latitude. We estimate the turbulence dissipation scale $r_{\text{in}}\approx 1500$ km toward the source J1833+0015.

arXiv comment16 pages, 12 figures, accepted for publication in MNRAS

References in corpus (41)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Control of star formation by supersonic turbulence
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Interstellar Turbulence I: Observations and Processes
• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• DiFX2: A more flexible, efficient, robust and powerful software correlator
• NE2001.I. A New Model for the Galactic Distribution of Free Electrons and its Fluctuations
• Vertical waves in the solar neighbourhood in Gaia DR2
• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• Locating the "missing" baryons with extragalactic dispersion measure estimates
• The third realization of the International Celestial Reference Frame by very long baseline interferometry
• Extending Big Power Law in the Sky with Turbulence Spectra from WHAM data
• Is Turbulence in the Interstellar Medium Driven by Feedback or Gravity? An Observational Test
• The Gaussian Plasma Lens in Astrophysics. Refraction
• The Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths
• Saturated-State Turbulence and Structure from Thermal and Magnetorotational Instability in the ISM: Three-Dimensional Numerical Simulations
• Closure statistics in interferometric data
• Milky Way scattering properties and intrinsic sizes of active galactic nuclei cores probed by very long baseline interferometry surveys of compact extragalactic radio sources
• A global view on star formation: The GLOSTAR Galactic Plane Survey. I. Overview and first results for the Galactic longitude range 28° < l < 36°
• mJIVE-20: a survey for compact mJy radio objects with the Very Long Baseline Array
• The Radio Fundamental Catalogue. I. Astrometry
• GLOSTAR -- Radio Source Catalog I: $28^{\circ }<\text{l}<36^{\circ }$ and $|b|<1^{\circ }$
• A global view on star formation: The GLOSTAR Galactic plane survey. II. Supernova Remnants in the first quadrant of the Milky Way
• VLBA observations of a rare multiple quasar imaging event caused by refraction in the interstellar medium
• A Catalogue of Radio Supernova Remnants and Candidate Supernova Remnants in the EMU/POSSUM Galactic Pilot Field
• Serendipitous VLBI detection of rapid, large-amplitude, intraday variability in QSO 1156+295
• Astrophysical Fractals: Interstellar Medium and Galaxies
• Tracing Milky Way scattering by compact extragalactic radio sources
• Proper motions of 15 pulsars: a comparison between Bayesian and frequentist algorithms
• Power-law models of totally anisotropic scattering
• Supernova Remnant Candidates Discovered by the SARAO MeerKAT Galactic Plane Survey
• A global view on star formation: The GLOSTAR Galactic plane survey. IX. Radio Source Catalog III: 2<l<28, 36<l<40, 56<l<60 and |b|<1, VLA B-configuration
• The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars
• Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13-0.11: Proof of the synchrotron nature by IXPE
• Scatter broadening of compact radio sources by the ionized intergalactic medium: Prospects for detection with Space VLBI and the SKA
• On the Enhanced Interstellar Scattering Toward B1849+005
• Search for and Identification of Young Compact Galactic Supernova Remnants Using THOR
• North Polar Spur: gaseous plume(s) from star-forming regions at $\sim$3-5 kpc from Galactic Center?
• FAST Pulsar Database: II. Scattering profiles of 149 Pulsars