  Atmospheric temperature and mixing ratio profiles of terrestrial planets vary
with the spectral energy flux distribution for different types of M-dwarf stars
and the planetary gravity. We investigate the resulting effects on the spectral
appearance of molecular absorption bands, that are relevant as indicators for
potential planetary habitability during primary and secondary eclipse for
transiting terrestrial planets with Earth-like biomass emissions. Atmospheric
profiles are computed using a plane-parallel, 1D climate model coupled with a
chemistry model. We then calculate simulated spectra using a line-by-line
radiative transfer model. We find that emission spectra during secondary
eclipse show increasing absorption of methane, water and ozone for planets
orbiting quiet M0-M3 dwarfs and the active M-type star AD Leo compared to solar
type central stars. However, for planets orbiting very cool and quiet M dwarfs
(M4 to M7), increasing temperatures in the mid-atmosphere lead to reduced
absorption signals, making the detection of molecules more difficult in such
scenarios. Transmission spectra during primary eclipse show strong absorption
features of CH4, N2O and H2O for planets orbiting quiet M0-M7 stars and AD Leo.
The N2O absorption of an Earth-sized planet orbiting a quiet M7 star can even
be as strong as the CO2 signal. However, ozone absorption decreases for planets
orbiting such cool central stars due to chemical effects in the atmosphere. To
investigate the effect on the spectroscopic detection of absorption bands with
potential future satellite missions, we compute signal-to-noise-ratios (SNR)
for a James Webb Space Telescope (JWST)-like aperture telescope.
