The Distribution of Astronomical Aldehydes – The Case for Extended Emission of Acetaldehyde (CH 3 CHO). Andrew Burkhardt 1,2 Ryan Loomis 3, Niklaus Dollhopf 1,2, Joanna Corby 1,2, Anthony Remijan 2 1 University of Virginia 2 NRAO 3 Harvard University

Distribution Implies Formation Routes Extended vs compact emission Hot vs cold Gas vs grain formation Distribution of different transitions can map out different components of molecular transitions ALMA gives us unprecedented capabilities to study the spatial distribution with incredible sensitivity

Why Aldehydes? Formaldehyde was the first organic polyatomic molecule detected in the ISM by Snyder et al. (1969) Formaldehydes and other simple aldehydes can, through formose reactions, produce sugars and ultimately ribose, the basis of RNA

Aldehydes as seen in Sgr B2(N) In Sgr B2(N), observed to have extended emission and potentially no compact emission (Chengalur and Kanekar, 2003) The extended distribution is also inferred for other aldehydes toward Sgr B2(N) including glycolaldehyde (Hollis et al., ApJ, 2001) and propynal. It is thought that there is an underlying formation mechanism to produce aldehydes in cold regions Is this unique to Sgr B2(N) or should we see this in other massive star forming regions (Orion KL)?

Acetaldehyde (CH 3 CHO) Has been detected in numerous sources, and multiple times in Orion KL with single dish (Turner 1989, 1991, PRIMOS survey at cv.nrao.edu/~aremijan/PRIMOS) Conflicting results from interferometric data Liu 2005 reports spatially coincident with HCOOH with BIMA Friedel 2008 reports a non-detection of HCOOH and CH 3 CHO with CARMA, implying extended emission is resolved out

Multiple Components Turner (1989, 1981) & Nummelin et al (2000) observed highly elevated b-type transitions in Orion KL compared to a-type, proposing radiative pumping of the low-lying vibrational states The ‘a’ dipole moment is 2.5 times larger than the ‘b’. In a given frequency range, the ‘b’-type transitions will have higher upper-state transitions Postulate that there could be multiple components (cold extended and hot compact). Need to map over multiple transitions and spatial scales

Orion KL Structure Friedel et al., 2008

ALMA/CARMA Observations Science Verification Band-6 Survey data of Orion KL 20x1.9 GHz spectral windows each with ~3800 channels High resolution/sensitivity Can map out all relevant transitions See TF04 by Remijan for more information CARMA B/E Array 7x62 MHz narrow band and 1x500 MHz wideband windows E Array (Max baseline 240 m) B Array (Max baseline 2395 m)

a-type transitions

Emission is seen as compact Both along the compact ridge and surrounding (but not in) the hot core

b-type transitions More compact emission, surround the hot core and at the compact ridge

CARMA E-Array Low-energy, cold extended emission (a-type transition) SW region seen in extended emission (E Array) Not seen in SV data due to loss of sensitivity in beam

CARMA E-Array b-type transitions (seen as compact in SV) unresolved in E- Array

CARMA B-Array Cold, extended emission is resolved out Very weak compact emission detected for these low energy transitions

t-HCOOH vs CH 3 CHO As predicted by Liu, cold extended emission of t-HCOOH is cospatial with CH 3 CHO, excluding SW region

CH 3 OH vs CH 3 CHO CH 3 OH and CH 3 OH are cospatial for the compact emission seen in SV data, with agreement with Friedel et al. (2011,2012) Unlike CH 3 CHO, CH 3 OH is abundant in the hot core due to not being fully destroyed during gas- grain warm up

CH 3 OH vs CH 3 CHO In addition to compact emission, CARMA E- Array detected cold- extended emission Futhermore, the SW region seen in CH 3 CHO are found for CH 3 OH emission

Conclusions ALMA: High-J transitions occur in compact emission CH 3 CHO is destroyed in hot core during grain- warm up CARMA: E-Array detects extended, cold emission B-Array detects limited compact emission surrounding the hot core

Thanks National Radio Astronomy Observatory Summer Student Program ALMA Science Verification Team Virginia Space Grant Consortium Collaborators and Peers