Unraveling the Mysteries of Complex Interstellar Organic Chemistry Using

HIFI Line Surveys

Susanna L. Widicus Weaver, Mary L. Radhuber, Jay A. Kroll, Brett A. McGuire, and Jacob C.

LaasDepartment of Chemistry, Emory University

Darek C. LisCalifornia Institute of Technology

Eric HerbstOhio State University

^ Observational Spectral

Why Molecular Line Surveys?

Our Goals:• Conduct surveys for many different types of sources• Achieve high spectral sensitivity (for new molecule

ID)• Obtain full picture of chemical, physical conditions

for each source• Compare results to astrochemical models

• New astrochemical models attempt to explain formation of complex organics

• Models require complete chemical, physical picture for input/comparison

• Physical parameters, abundances often educated guesses

• Few surveys access differing chemical, physical environments

Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008

Tracing Chemical Pathways in the ISMH2O + hn OH + H

H2 + O

CH3OH + hn CH3 + OHCH3O + HCH2OH + H

NH3 + hn NH2 + H

H2CO + hn HCO + H

HCO + CH2OH HOCH2CHO (glycolaldehyde)HCO + CH3O CH3OCHO (methyl formate)HCO + OH HCOOH (formic acid)HCO + CH3 CH3CHO (acetaldehyde)HCO + NH2 H2NCHO (formamide)CH3 + CH3O CH3OCH3 (dimethyl ether)CH3 + NH2 CH3NH2 (methyl amine)CH3 + CH2OH CH3CH2OH (ethanol)CH2OH + CH2OH HOCH2CH2OH (ethylene glycol)

hn

H2O, CO, CH3OH, NH3 , H2CO Ice mantle

Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008

CSO Orion Spectrum

3018 >3-s lines observed

59% of the lines are unassigned!

See talk FA05 (Radhuber et al.) for more information.

Results of Spectral Analysis

Residual = incomplete modeling of complex lineshapes + unassigned lines of known molecules + very weak lines from COMs

CSO Line Surveys

Full surveys complete for 8 sources, partial surveys complete for 5 more.

CH3OH HCOOCH3

& CH3OHCH3OCH3 CH3OH

& CH3CNCH3OH

Ta*

(K)

HCOOCH3

THz Observational Astronomy

480 GHz -1.2 THz

1.4 – 1.9 THz

Herschel Space

Observatory

Launched in 2009

Stratospheric Observatory for

Infrared AstronomyScience observations began

in 2010500 GHz – 2.1 THz

Atacama Large Millimeter Array

Early science observations to begin in 201180 GHz – 950 GHz

ESO/José Francisco Salgado

ESA / AOES Medialab background: HST, NASA/ ESA/ STScI

NASA / DLR

Upcoming Herschel Observations

The Importance of Follow-Up Imaging Studies

Friedel and Widicus Weaver, in preparation.

Orion-KL l = 3 mm continuum observations with CARMA

Revealing Chemistry Through Imaging

Different COMs have very different spatial distributions.

Neill et al., J. Phys. Chem., in press.

CARMA+

MF1

Methanol Formic acid Dimethyl ether

Friedel and Widicus Weaver, CARMA, 2008NRAO EVLA Demonstration 2009

Comparison of Methyl Formate in Orion-KL to other COMs

http://amandabauer.blogspot.com/2009/08/carma-telescopes.html

Proposed CARMA Observations

CSO Survey of Orion-KLRMS = 30 mK

Integration Time ~ 4 Nights

Full ALMA Capability Similar coverage on Orion-KL

RMS = 30 mKIntegration Time ~ 1 Minute

OVRO Survey of Orion-KLRMS = 150 mK

Integration Time ~ 27 Nights

eVLA Demonstration ScienceImage courtesy of NRAO https://science.nrao.edu/facilities/evla/earlyscience/demoscience

Blake et al. 1987, ApJ 315, 621

Radhuber et al., in preparation.

ALMA Changes Everything

• CSO surveys at 230 GHz8 GHz spectrometer = More sources in less time

• HIFI line surveys at 680 GHz & 1.2 THzOT-1 observations 2011/2012OT-2 proposals due September 15

• CARMA imaging at 230 GHzProposal review this week

• ALMA imaging at 680 GHzCycle-0 proposals due June 30

• Comparison to modelsID molecules that trace gas-phase or grain-surface

chemistryCompare relative abundances of isomers,

conformers

• Future observationsCSO 345 GHz receiver + 8 GHz spectrometerSOFIA

Future Work

http://www.nasa.gov/centers/jpl/images/content/391019main_herschel-b-20091002-full.jpg

AcknowledgementsThe Widicus Weaver Group:Brian Hays, Le Zhong, Cate Levey, Jay Kroll, Jake Laas, Brett McGuire, Mary Radhuber, Brandon Carroll, Sophie Lang, Anne Carroll

CSO/Caltech: Jonas Zmuidzinas, Tom Phillips, Geoffrey Blake, CSO Staff & TAC

HIFI/HEXOS: Ted Bergin, Nathan Crockett, Claudia Comito, Peter Schilke, Martin Emprechtinger, Steve Lord

UIUC/CARMA: Doug Friedel

NRAO/ALMA: Anthony Remijan