The HI/OH/Recombination line survey of the inner Milky Way (THOR): data release 2 and Hi overview

Context. The Galactic plane has been observed extensively by a large number of Galactic plane surveys from infrared to radio wavelengths at an angular resolution below 40". However, a 21 cm line and continuum survey with comparable spatial resolution is still missing. Aims. The first half of THOR data (l = 14.0 37.9, and l = 47.1 51.2, |b| < 1.25) has been published in our data release 1 paper (Beuther et al. 2016). With this data release 2 paper, we publish all the remaining spectral line data and Stokes I continuum data with high angular resolution (1000–4000) including a new H i dataset for the whole THOR survey region (l = 14.0 67.4 and |b| < 1.25). As we have published the results of OH lines and continuum emission elsewhere, we concentrate on the H i analysis in this paper. Methods. With the Karl G. Jansky Very Large Array (VLA) in C-configuration, we observed a large portion of the first Galactic quadrant achieving an angular resolution of < 40. At L Band, the WIDAR correlator at the VLA was set to cover the 21 cm H i line, four OH transitions, a series of Hn↵ radio recombination lines (RRLs; n = 151 to 186), and eight 128 MHz wide continuum spectral windows (SPWs) simultaneously. Results. We publish all OH and RRL data from the C-configuration observations, and a new H i dataset combining VLA C+D+GBT (VLA D-configuration and GBT data are from the VLA Galactic Plane Survey, Stil et al. 2006) for the whole survey. The H i emission shows clear filamentary substructures at negative velocities with low velocity crowding. The emission at positive velocities is more smeared-out likely due to higher spatial and velocity crowding of structures at the positive velocities. Comparing to the spiral arm model of the Milky Way, the atomic gas follows the Sagittarius and Perseus Arm well but with significant material in the inter-arm regions. With the C-configuration-only H i+continuum data, we produced a H i optical depth map of the THOR areal coverage from 228 absorption spectra with the nearest-neighbor method. With this ⌧ map, we corrected the H i emission for optical depth and the derived column density is 38% higher than the column density with optically thin assumption. The total H i mass with optical depth correction in the survey region is 4.7⇥108 M, 31% more than the mass derived assuming the emission is optically thin. If we apply this 31% correction to the whole Milky Way, the total atomic gas mass would be 9.4–10.5⇥109 M. Comparing the H i with existing CO data, we find a significant increase in the atomic-to-molecular gas ration from the spiral arms to the inter-arm regions. Conclusions. The high sensitivity and resolution THOR H i dataset provides an important new window on the physical and kinematic properties of gas in the inner Galaxy. Although the optical depth we derive is a lower limit, our study shows that the optical depth correction is significant for H i column density and mass estimation. Together with the OH, RRL and continuum emission from the THOR survey, these new H i data provide the basis for high angular-resolution studies of the interstellar medium (ISM) in different phases

Feedback in W94A diagnosed with Radio Recombination Lines and Models

We present images of radio recombination lines (RRLs) at wavelengths around 18 cm from the star-forming region W49A to determine the kinematics of ionized gas in the THOR survey (The Hi/OH/Recombination line survey of the inner Milky Way) at an angular resolution of 16:08 X 13:08. The distribution of ionized gas appears to be affected by feedback processes from the star clusters inW49A. The velocity structure of the RRLs shows a complex behaviour with respect to the molecular gas. We find a shell-like distribution of ionized gas as traced by RRL emission surrounding the central cluster of OB stars in W49A. We describe the evolution of the shell with the recent feedback model code warpfield that includes the important physical processes and has previously been applied to the 30 Doradus region in the Large Magellanic Cloud. The cloud structure and dynamics of W49A are in agreement with a feedbackdriven shell that is re-collapsing. The shell may have triggered star formation in other parts of W49A. We suggest that W49A is a potential candidate for star formation regulated by feedback-driven and re-collapsing shells

Measurement of jet-substructure observables in top quark, W boson and light jet production in proton-proton collisions at √s=13 TeV with the ATLAS detector

A measurement of jet substructure observables is presented using data collected in 2016 by the ATLAS experiment at the LHC with proton-proton collisions at s√ = 13 TeV. Large-radius jets groomed with the trimming and soft-drop algorithms are studied. Dedicated event selections are used to study jets produced by light quarks or gluons, and hadronically decaying top quarks and W bosons. The observables measured are sensitive to substructure, and therefore are typically used for tagging large-radius jets from boosted massive particles. These include the energy correlation functions and the N-subjettiness variables. The number of subjets and the Les Houches angularity are also considered. The distributions of the substructure variables, corrected for detector effects, are compared to the predictions of various Monte Carlo event generators. They are also compared between the large-radius jets originating from light quarks or gluons, and hadronically decaying top quarks and W bosons

Measurement of jet-substructure observables in top quark, W boson and light jet production in proton-proton collisions at root s=13 TeV with the ATLAS detector

A measurement of jet substructure observables is presented using data collected in 2016 by the ATLAS experiment at the LHC with proton-proton collisions at root s= 13 TeV. Large-radius jets groomed with the trimming and soft-drop algorithms are studied. Dedicated event selections are used to study jets produced by light quarks or gluons, and hadronically decaying top quarks and W bosons. The observables measured are sensitive to substructure, and therefore are typically used for tagging large-radius jets from boosted massive particles. These include the energy correlation functions and the N-subjettiness variables. The number of subjets and the Les Houches angularity are also considered. The distributions of the substructure variables, corrected for detector effects, are compared to the predictions of various Monte Carlo event generators. They are also compared between the large-radius jets originating from light quarks or gluons, and hadronically decaying top quarks and W bosons