your ID: 0294 
First Name: Mai 
Last Name: Shirahata 
Affiliation: ISAS/JAXA 

Title: Detection of Warm Molecular Clouds toward the Obscured AGN IRAS 08572+3915 
Authors: Mai Shirahata, Takao Nakagawa, Miwa Goto, Tomonori Usuda, Hiroshi Suto, and T. R. Geballe 
Topic: 6 
Session: oral 
Abstract: It is generally accepted that much of the variety in Active Galactic Nuclei (AGN) 
types is the result of varying orientation relative to the line of sight (unified model for AGN). 
Molecular tori are the key element of this model. However, physical conditions of the tori have 
never been observed directly, and the exact nature of the molecular tori is still controversial. 

In order to investigate physical conditions of molecular tori in obscured AGN directly, we 
have made spectroscopic observations of the ultra luminous infrared galaxy IRAS 08572+3915. 
We observe fundamental ro-vibration absorption lines of gaseous CO in M-band using the central 
engine as a background continuum source. This is a unique technique which enable us to determine 
temperature and column densities of molecular clouds very accurately. 

We have detected many absorption lines up to highly excited rotational levels (J<=17), which show 
the presence of warm (~300 K) molecular gas. This warm component is highly blueshifted (-160 km/s) 
relative to the systemic velocity of the galaxy and its velocity width is > 200 km/s.  Two other 
components, one near 0 km/s and one near +100 km/s are also detected. We show these observation 
results and discuss the physical condition of the molecular gas.