Multi-Channel Spectroscopy (VKS)
An IFU investigation of possible Lyman continuum
An IFU investigation of possible Lyman continuum escape from Mrk 71/NGC 2366
Micheva, G.; Herenz, C. E.; Roth, M.M.; Östlin, G.; Girichidis, P
Mrk 71/NGC 2366 is the closest Green Pea (GP) analog and candidate Lyman Continuum (LyC) emitter. Recently, 11LyC-leaking GPs have been detected through direct observations of the ionizing continuum, making this the most abundant classof confirmed LyC-emitters at any redshift. High resolution, multi-wavelength studies of GPs can lead to an understanding of themethod(s), through which LyC escapes from these galaxies.Aims.The proximity of Mrk 71/NCG 2366 offers unprecedented detail on the inner workings of a GP analog, and enables us toidentify the mechanisms of LyC escape.Methods.We use 5825-7650Å integral field unit PMAS observations to study the kinematics and physical conditions in Mrk 71. Anelectron density map is obtained from the [S II] ratio. A fortuitous second order contamination by the [O II]λ3727 doublet enablesthe construction of an electron temperature map. Resolved maps of sound speed, thermal broadening, “true” velocity dispersion, andMach number are obtained and compared to the high resolution magneto-hydrodynamic SILCC simulations.Results.Two regions of increased velocity dispersion indicative of outflows are detected to the north and south of the super star cluster,knot B, with redshifted and blueshifted velocities, respectively. We confirm the presence of a faint broad kinematical component,which is seemingly decoupled from the outflow regions, and is fainter and narrower than previously reported in the literature. Withinuncertainties, the low- and high-ionization gas move together. Outside of the core of Mrk 71, an increase in Mach numbers is detected,implying a decrease in gas density. Simulations suggest this drop in density can be as high as∼4 dex, down to almost optically thinlevels, which would imply a non-zero LyC escape fraction along the outflows even when assuming all of the detected H I gas is locatedin front of Mrk 71 in the line of sight.Conclusions.Our results strongly indicate that kinematical feedback is an important ingredient for LyC leakage in GPs.
Journal Article