Radio Astronomy visibility data discovery and access using IVOA standards

Enhancing interoperable data access to radio data has become a science priority within the International Virtual Observatory Alliance (IVOA). This lead to the foundation of the IVOA Radio astronomy Interest Group. Several radio astronomers and project scientists enrolled in various projects (NRAO, ASKAP, LOFAR, JIVE, ALMA, SKA, INAF, NenuFAR, etc.) have joined. Together they are paving the way to a better integration of their services in the virtual observatory (VO) infrastructure and propose extension of IVOA standards to help achieving this goal. Calibrated radio datasets such as cubes, images, spectra and time series can already be searched and retrieved using the ObsCore/ObsTAP specification defined in the IVOA, or by data product-specific services like SIAv2, SODA, SSA and ConeSearch. However, properties of radio visibility data are not fully implemented in the VO landscape yet. We need specific features to refine data discovery and selection that are adapted to radio astronomers' need. In this context the VO team at the Centre de Donn\'{e}es astronomiques de Strasbourg (CDS) proposes to consider the ObsCore/ObsTAP specification and to establish cross-walks between the ObsCore and the existing Measurement Set (MS) metadata profile for data discovery of radio visibility data (VD). In order to account for the difference in granularity between radio VD datasets and science-ready datasets of the VO, the approach splits a MS data file into a list of datasets served by an ObsTAP service, thus enabling coarse grain discovery in the multi-wavelength context. Radio specific metadata such as number of antennae, frequency ranges, $uv$ plane coverage plots, frequency-phase and frequency-amplitude plots, primary and synthesized beams are also provided either by adding column metadata or by using the DataLink technique.Comment: 4 pages, 2 figures, ADASS XXX Conference Proceedings Nov 202

CHANG-ES XXVII: A Radio/X-ray Catalogue of Compact Sources in and around Edge-on Galaxies

We present catalogues of discrete, compact radio sources in and around the discs of 35 edge-on galaxies in the Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES). The sources were extracted using the PyBDSF program at both 1.6 GHz (L-band) and 6.0 GHz (C-band) from matching resolution ($\approx$ 3 arcsec) data. We also present catalogues of X-ray sources from Chandra data sets for 27 of the galaxies. The sources at the two radio frequency bands were positionally cross-correlated with each other, and the result cross-correlated with the X-ray sources. All catalogues are included for download with this paper. We detect a total of 2507 sources at L-band and 1413 sources at C-band. Seventy-five sources have been successfully cross-correlated in both radio bands plus X-ray. Three new nuclear sources are candidates for Low Luminosity Active Galactic Nuclei in NGC~3877, NGC~4192, and NGC~5792; the one in NGC~3877 also appears to be variable. We also find new nuclear sources in two companion galaxies: NGC~4435 (companion to NGC~4438) and NGC~4298 (companion to NGC~4302). We have also discovered what appears to be a foreground double-star; each star has X-ray emission and there is radio emission at both L-band and C-band in between them. This could be a colliding wind binary system. Suggestions for follow-up studies are offered.Comment: Accepted to MNRAS, 57 pages of which pages 30 to 57 are figures. 5 ancillary files containing tabular information, as explained in the appendice

CHANG-ES XI: Circular Polarization in the Cores of Nearby Galaxies

We detect 5 galaxies in the CHANG-ES (Continuum Halos in Nearby Galaxies -- an EVLA Survey) sample that show circular polarization (CP) at L-band in our high resolution data sets. Two of the galaxies (NGC~4388 and NGC~4845) show strong Stokes $V/I\,\equiv\,m_C\,\sim\,2$\%, two (NGC~660 and NGC~3628) have values of $m_C\sim \,0.3$\%, and NGC~3079 is a marginal detection at $m_C\sim \,0.2$\%. The two strongest $m_C$ galaxies also have the most luminous X-ray cores and the strongest internal absorption in X-rays. We have expanded on our previous Faraday conversion interpretation and analysis and provide analytical expressions for the expected $V$ signal for a general case in which the cosmic ray electron energy spectral index can take on any value. We provide examples as to how such expressions could be used to estimate magnetic field strengths and the lower energy cutoff for CR electrons. Four out of our detections are {\it resolved}, showing unique structures, including a {\it jet} in NGC~4388 and a CP `conversion disk' in NGC~4845. The conversion disk is inclined to the galactic disk but is perpendicular to a possible outflow direction. Such CP structures have never before been seen in any galaxy to our knowledge. None of the galaxy cores show linear polarization at L-band. Thus CP may provide a unique probe of physical conditions deep into radio AGNs.Comment: 30 pages, 4 figures, accepted to MNRA

CHANG-ES IV: Radio continuum emission of 35 edge-on galaxies observed with the Karl G. Jansky Very Large Array in D-configuration, Data Release 1

We present the first part of the observations made for the Continuum Halos in Nearby Galaxies, an EVLA Survey (CHANG-ES) project. The aim of the CHANG-ES project is to study and characterize the nature of radio halos, their prevalence as well as their magnetic fields, and the cosmic rays illuminating these fields. This paper reports observations with the compact D configuration of the Karl G. Jansky Very Large Array (VLA) for the sample of 35 nearby edge-on galaxies of CHANG-ES. With the new wide bandwidth capabilities of the VLA, an unprecedented sensitivity was achieved for all polarization products. The beam resolution is an average of 9.6" and 36" with noise levels reaching approximately 6 and 30 microJy per beam for C- and L-bands, respectively (robust weighting). We present intensity maps in these two frequency bands (C and L), with different weightings, as well as spectral index maps, polarization maps, and new measurements of star formation rates (SFRs). The data products described herein are available to the public in the CHANG-ES data release available at www.queensu.ca/changes. We also present evidence of a trend among galaxies with larger halos having higher SFR surface density, and we show, for the first time, a radio continuum image of the median galaxy, taking advantage of the collective signal-to-noise ratio of 30 of our galaxies. This image shows clearly that a typical spiral galaxy is surrounded by a halo of magnetic fields and cosmic rays.Comment: 70 pages, of which 35 pages present the data of each galax

CHANG-ES X: Spatially-resolved Separation of Thermal Contribution from Radio Continuum Emission in Edge-on Galaxies

We analyze the application of star formation rate (SFR) calibrations using H$\alpha$ and 22 micron infrared imaging data in predicting the thermal radio component for a test sample of 3 edge-on galaxies (NGC 891, NGC 3044, and NGC 4631) in the Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES). We use a mixture of H$\alpha$ and 24 micron calibration from Calzetti et al. (2007), and a linear 22 micron only calibration from Jarrett et al. (2013) on the test sample. We apply these relations on a pixel-to-pixel basis to create thermal prediction maps in the two CHANG-ES bands: L- and C-band (1.5 GHz and 6.0 GHz, respectively). We analyze the resulting non-thermal spectral index maps, and find a characteristic steepening of the non-thermal spectral index with vertical distance from the disk after application of all methods. We find possible evidence of extinction in the 22 micron data as compared to 70 micron Spitzer Multband Imaging Photometer (MIPS) imaging in NGC 891. We analyze a larger sample of edge-on and face-on galaxy 25 micron to 100 micron flux ratios, and find that the ratios for edge-ons are systematically lower by a factor of 1.36, a result we attribute to excess extinction in the mid-IR in edge-ons. We introduce a new calibration for correcting the H$\alpha$ luminosity for dust when galaxies are edge-on or very dusty.Comment: Accepted for publication in ApJ on December 24, 2017, 23 pages, 19 figure

XIV. Cosmic-ray propagation and magnetic field strengths in the radio halo of NGC4631

Mora-Partiarroyo SC, Krause M, Basu A, et al. XIV. Cosmic-ray propagation and magnetic field strengths in the radio halo of NGC4631. ASTRONOMY & ASTROPHYSICS. 2019;632: A10.Aims. NGC4631 is an interacting galaxy that exhibits one of the largest, gaseous halos observed among edge-on galaxies. We aim to examine the synchrotron and cosmic-ray propagation properties of its disk and halo emission with new radio continuum data. Methods. Radio continuum observations of NGC4631 were performed with the Karl G. Jansky Very Large Array at C-band (5.99 GHz) in the C and D array configurations, and at L-band (1.57 GHz) in the B, C, and D array configurations. Complementary observations of NGC4631 with the E ffelsberg telescope were performed at 1.42 and 4.85 GHz. The interferometric total intensity data were combined with the single-dish E ffelsberg data in order to recover the missing large-scale total power emission. The thermal and nonthermal components of the total radio emission were separated by estimating the thermal contribution through the extinction-corrected H alpha emission. The Hff radiation was corrected for extinction using a linear combination of the observed H alpha and 24 mu m data. Results. NGC4631 has a global thermal fraction at 5.99 (1.57) GHz of 14 +/- 3% (5.4 +/- 1.1%). The mean scale heights of the total emission in the radio halo (thick disk) at 5.99 (1.57) GHz are 1 .79 +/- 0 .54 kpc (1 .75 +/- 0 .27 kpc) and have about the same values for the synchrotron emission. The total magnetic field of NGC4631 has a mean strength of similar or equal to 9 mu G in the disk, and a mean strength of similar or equal to 7 mu G in the halo. We also studied a double-lobed background radio galaxy southwest of NGC4631, which is an FR II radio galaxy according to the distribution of spectral index across the lobes. Conclusions. From the halo scale heights we estimated that the radio halo is escape-dominated with convective cosmic ray propagation, and conclude that there is a galactic wind in the halo of NGC4631

CHANG-ES XXIX: the sub-kpc nuclear bubble of NGC 4438

Active galactic nucleus (AGN) bubbles could play an important role in accelerating high-energy cosmic rays (CRs) and galactic feedback. Only in nearby galaxies could we have high enough angular resolution in multiwavelengths to study the sub-kpc environment of the AGN, where the bubbles are produced and strongly interact with the surrounding interstellar medium. In this paper, we present the latest Chandra observations of the Virgo cluster galaxy NGC 4438, which hosts multiscale bubbles detected in various bands. The galaxy also has low current star formation activity, so these bubbles are evidently produced by the AGN rather than a starburst. We present spatially resolved spectral analysis of the Chandra data of the ∼3 arcsec × 5 arcsec (⁠∼200 pc×350 pc⁠) nuclear bubble of NGC 4438. The power-law tail in the X-ray spectra can be most naturally explained as synchrotron emission from high-energy CR leptons. The hot gas temperature increases, while the overall contribution of the non-thermal X-ray emission decreases with the vertical distance from the galactic plane. We calculate the synchrotron cooling time-scale of the CR leptons responsible for the non-thermal hard X-ray emission to be only a few tens to a few hundreds of years. The thermal pressure of the hot gas is about three times the magnetic pressure, but the current data cannot rule out the possibility that they are still in pressure balance. The spatially resolved spectroscopy presented in this paper may have important constraints on how the AGN accelerates CRs and drives outflows. We also discover a transient X-ray source only ∼5 arcsec from the nucleus of NGC 4438. The source was not detected in 2002 and 2008, but became quite X-ray bright in 2020 March, with an average 0.5–7 keV luminosity of ∼1039 erg s−1⁠. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.The authors also acknowledge the financial support from NASA and the Chandra X-ray Center through the grant GO9-20074X. TW acknowledges financial support from the coordination of the participation in SKA-SPAIN, financed by the Ministry of Science and Innovation (MCIN), and from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the ‘Centre of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709).Peer reviewe

Central curation of Glasgow Outcome Scale-Extended data: lessons learned from TRACK-TBI

The Glasgow Outcome Scale (GOS) in its original or extended (GOSE) form is the most widely used assessment of global disability in traumatic brain injury (TBI) research. Several publications have reported concerns about assessor scoring inconsistencies, but without documentation of contributing factors. We reviewed 6801 GOSE assessments collected longitudinally, across 18 sites in the 5-year, observational Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. We recorded error rates (i.e., corrections to a section or an overall rating) based on site assessor documentation and categorized scoring issues, which then informed further training. In Cohort 1 (n=1261; 2/2014-5/2016), 24% of GOSEs had errors identified by central review. In Cohort 2 (n=1130; 6/2016-7/2018), acquired following curation of Cohort 1 data, feedback, and further training of site assessors, the error rate was reduced to 10%. GOSE sections associated with the most frequent interpretation and scoring difficulties included whether current functioning represented a change from pre-injury (466 corrected ratings in Cohort 1; 62 in Cohort 2), defining dependency in the home and community (163 corrections in Cohort 1; 3 in Cohort 2); and return to work/school (72 corrections in Cohort 1; 35 in Cohort 2). These results highlight the importance of central review in improving consistency across sites and over time. Establishing clear scoring criteria, coupled with ongoing guidance and feedback to data collectors, is essential to avoid scoring errors and resultant misclassification, which carry potential to result in “failure” of clinical trials that rely on the GOSE as their primary outcome measure