The non-linear infrared-radio correlation of low-z galaxies: implications for redshift evolution, a new radio SFR recipe, and how to minimize selection bias

The infrared-radio correlation (IRRC) underpins many commonly used radio luminosity-star formation rate (SFR) calibrations. In preparation for the new generation of radio surveys we revisit the IRRC of low-z galaxies by (a) drawing on the best currently available IR and 1.4 GHz radio photometry, plus ancillary data over the widest possible area, and (b) carefully assessing potential systematics. We compile a catalogue of ∼9,500 z < 0.2 galaxies and derive their 1.4 GHz radio (L1.4), total IR, and monochromatic IR luminosities in up to seven bands, allowing us to parameterize the wavelength-dependence of monochromatic IRRCs from 22-500 μm. For the first time for low-z samples, we quantify how poorly matched IR and radio survey depths bias measured median IR/radio ratios, q¯¯TIR , and discuss the level of biasing expected for low-z IRRC studies in ASKAP/MeerKAT fields. For our subset of ∼2,000 high-confidence star-forming galaxies we find a median q¯¯TIR of 2.54 (scatter: 0.17 dex). We show that q¯¯TIR correlates with L1.4, implying a non-linear IRRC with slope 1.11±0.01. Our new L1.4-SFR calibration, which incorporates this non-linearity, reproduces SFRs from panchromatic SED fits substantially better than previous IRRC-based recipes. Finally, we match the evolutionary slope of recently measured q¯¯TIR -redshift trends without having to invoke redshift evolution of the IRRC. In this framework, the redshift evolution of q¯¯TIR reported at GHz frequencies in the literature is the consequence of a partial, redshift-dependent sampling of a non-linear IRRC obeyed by low-z and distant galaxies

MeerKAT-16 HI observation of the dIrr galaxy WLM

We present observations and models of the kinematics and the distribution of the neutral hydrogen (Hi) in the isolated dwarf irregular galaxy, Wolf-Lundmark-Melotte (WLM). We observed WLM with the Green Bank Telescope (GBT) and as part of the MeerKAT Early Science Programme, where 16 dishes were available. The Hi disc of WLM extends out to a major axis diameter of 300 (8.5 kpc), and a minor axis diameter of 200 (5.6 kpc) as measured by the GBT. We use the MeerKAT data to model WLM using the TiRiFiC software suite, allowing us to t di erent tilted-ring models and select the one that best matches the observation. Our nal best- tting model is a at disc with a vertical thickness, a constant inclination and dispersion, and a radially-varying surface brightness with harmonic distortions. To simulate bar- like motions, we include second-order harmonic distortions in velocity in the tangential and the vertical directions. We present a model with only circular motions included and a model with non-circular motions. The latter describes the data better. Overall, the models reproduce the global distribution and the kinematics of the gas, except for some faint emission at the 2 level. We model the mass distribution of WLM with a pseudo-isothermal (ISO) and a Navarro-Frenk-White (NFW) dark matter halo models. The NFW and the ISO models t the derived rotation curves within the formal errors, but with the ISO model giving better reduced chi-square values. The mass distribution in WLM is dominated by dark matter at all radii.The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the Na- tional Research Foundation, an agency of the Department of Science and Innovation. This work is based upon research supported by the South African Research Chairs Initiative of the Department of Sci- ence and Technology and National Research Foundation. The nancial assistance of the South African Radio Astron- omy Observatory (SARAO) towards this research is hereby acknowledged (www.sarao.ac.za). PK is partially supported by the BMBF project 05A17PC2 for D-MeerKAT. AS acknowledges the Russian Science Foundation grant 19-12-00281 and the Program of development of M.V.http://mnras.oxfordjournals.orgam2021Physic

GASP XXVI. HI gas in jellyfish galaxies : the case of JO201 and JO206

Please read abstract in the article.European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme grant agreement no. 679627 and no.833824, project name FORNAX and GASP, respectively. We acknowledge funding from the agreement ASI-INAF n.2017-14-H.0, as well as from the INAF main-stream funding programme. M. R’s research is supported by the SARAO HCD programme via the "New Scientific Frontiers with Precision Radio Interferometry" research group grant. M. R. acknowledges support from the Italian Ministry of Foreign A airs and International Cooperation (MAECI Grant Number ZA18GR02) and the South African Department of Science and Technology’s National Research Foundation (DST-NRF Grant Number 113121) as part of the ISARP RADIOSKY2020 Joint Research Scheme. B. V. and M. G. also acknowledge the Italian PRIN-Miur 2017 (PI A. Cimatti). Y. J. acknowledges financial support from CONICYT PAI (Concurso Nacional de Insercion en la Academia 2017), No. 79170132 and FONDECYT Iniciación 2018 No. 11180558. M. V. acknowledges support by the Netherlands Foundation for Scientific Research (NWO) through VICI grant 016.130.338.http://www.aanda.orgam2020Physic

The extended H i halo of NGC 4945 as seen by MeerKAT

The State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the ‘Center of Excellence Severo Ochoa’ awarded to the Instituto de Astrofísica de Andalucía; the Economic Transformation, Industry, Knowledge and Universities Council of the Regional Government of Andalusia and the European Regional Development Fund from the European Union; the South African Radio Astronomy Observatory (SARAO); BMBF Verbundforschung; DFG Sonderforschungsbereich and the European Research Council (ERC).http://mnras.oxfordjournals.orghj2022Physic

Anomalous gas in ESO 149-G003 : a MeerKAT-16 view

ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen (⁠HI⁠) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar HI component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy’s morphology, which shows a high degree of asymmetry. By comparing our model with the observed HI⁠, we find that in our model, we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube, we estimate that at least 7–8 per cent of the HI in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1 per cent for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material.http://mnras.oxfordjournals.orghj2022Physic

Search for Dark Matter and Supersymmetry with a Compressed Mass Spectrum in the Vector Boson Fusion Topology in Proton-Proton Collisions at root s=8 TeV

Peer reviewe

Measurements of the t(t)over-bar production cross section in lepton plus jets final states in pp collisions at 8 and ratio of 8 to 7 TeV cross sections

Peer reviewe

Search for lepton flavour violating decays of the Higgs boson to eτand eμin proton–proton collisions at √s=8TeV

A direct search for lepton flavour violating decays of the Higgs boson (H) in the H →eτand H →eμchannels is described. The data sample used in the search was collected in proton–proton collisions at √s=8TeVwith the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7fb−1. No evidence is found for lepton flavour violating decays in either final state. Upper limits on the branching fractions, B(H →eτ) <0.69%and B(H →eμ) <0.035%, are set at the 95% confidence level. The constraint set on B(H →eτ)is an order of magnitude more stringent than the existing indirect limits. The limits are used to constrain the corresponding flavour violating Yukawa couplings, absent in the standard model