Infrared spectroscopy of nearby radio active early-type galaxies - II: spectral atlas

Mark Durre, Jeremy Mould, Michael Brown, Tristan Reynolds

Research output: Contribution to journalArticlepeer-review


We present a near-infrared spectroscopic atlas of nearby, bright early-type galaxies with radio emission, containing 163 galaxies observed by the Palomar 200″ TripleSpec instrument, measuring the emission line fluxes for H, He, [Fe ii], and H2 and determined the nuclear excitation mechanisms. By stacking spectra, we deduced the H2 excitation temperature (1957 ± 182 K) and dominant excitation mechanism (thermal and shock heating combined) from the K-band emission line sequence. Stacking also produces an 'average' spectrum of absorption features and spectral indices from the literature; the CO12 absorption line index versus J - K colour shows a trend of stronger nuclear activity producing a weaker CO12 index and a redder (flatter) continuum. The correlations between the radio and the emission-line luminosities finds a trend with radio power; however, the large scatter in the upper limits shows that the two are not directly coupled and the duty cycles of SF and AGN activity are not synchronized.

Original languageEnglish
Pages (from-to)4923-4938
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 12 Jul 2023


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