New Paper Published: [CII] excess in HE1353-1917

Tuesday, May 28, 2019

Our PhD student Irina Smirnova-Pinchukova used FIR observations with the flying observatory SOFIA aboard Boeing 747SP to study the [CII] 158µm emission line in a sample of 5 AGN host galaxies from the CARS sample. Irina discovered that, surprisingly, one of the targeted galaxies, named HE1353-1917 at z=0.035, exhibits ten times higher [CII] luminosity than expected from the star formation rate. Hence, there is an additional excitation mechanism at work in this specific galaxy that is injecting additional energy in the ISM which cooling through the [CII] line. A companion paper by the PI of CARS, Bernd Husemann, is discussing the properties of a massive multi-phase AGN-driven outflow on kpc scales also discovered in this galaxy. Since the [CII] excess is confirmed to originate from the galaxy center, Irina argues that the [CII] excess is directly powered by the shocked-heated gas in the outflows. Our observations at low redshift are crucial to interpret [CII] observations of high redshift galaxies with ALMA.

[CII] 158µm luminosity as a function of FIR luminosity as a proxy for the ongoing star formation rate. All of our CARS targets observed with SOFIA follow the same relation as all galaxies in the local Universe. Only the galaxy HE1353-1917 is clearly deviating from the trend and shows an order of magnitude excess of [CII].