IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A031 PROGRAM_TITLE The first near-IR spectroscopic campaign in conjunction with an approved Hubble Space Telescope UV campaign to map the dust in the torus and accretion disk in the AGN Mrk 817 PROGRAM_INV1 Jake Mitchell PROGRAM_INV2 Hermine Landt PROGRAM_INV3 Martin Ward PROGRAM_INV4 Bradley Peterson PROGRAM_INV5 Keith Horne PROGRAM_SCICAT extra-galactic PROGRAM_ABSTRACT_BEG The most promising technique to constrain the location of the dusty torus is reverberation, i.e., measuring the time the dust needs to respond to changes in the irradiating flux. Here we wish to build on our successful spectroscopic monitoring campaigns of the dusty torus in AGN and observe Mrk 817, which is the target of a recently approved Hubble Space Telescope [HST] UV campaign. This is a rare opportunity since only one such HST campaign exists so far [on NGC 5548]. Near-IR spectroscopy, unlike photometry, can explore several signatures of the hot dust, such as its flux and temperature, measure the dust response at several frequencies and also the variability of associated emission lines, e.g., the coronal lines. But most importantly, only a spectroscopic monitoring campaign can constrain the astrochemistry of the dust surrounding supermassive black holes by measuring the luminosity-based radius simultaneously with the lag times. Besides the lags of different emission lines, the HST data will provide an exquisitely sampled UV continuum light-curve as the driver, which is more variable than the optical light-curve and is a direct measure of the [accretion disk] radiation heating the dust. We propose to observe with SpeX in the short cross-dispersed [SXD] mode weekly for the whole of this semester. We will use the 0.3 arcsec slit, which at the distance of Mrk 817 excludes most of the host galaxy flux and gives the spectral resolution required to study line profile changes in addition to flux variability. PROGRAM_ABSTRACT_END