1. Spectral Line Surveys with the CSO Susanna L. Widicus Weaver, Department of Chemistry, Emory University Matthew Sumner, Frank Rice, Jonas Zmuidzinas, Department of Physics, Caltech Geoffrey Blake, Department of Geological & Planetary Sciences, Department of Chemistry, Caltech

2. The Widicus Weaver Group Mary Radhuber Jay Kroll Brandon Carroll Jake Laas Thomas Anderson

3. New Receiver Technology at the CSO “Z-Rex” receiver designed for external galaxy searches at high-z Broad frequency coverage High S/N Double sideband (DSB) receiver Facility CSO ReceiversZ-Rex T sys (K, SSB)120100 Spectral (IF) Bandwidth (GHz) 1 4 Z-Rex is an ideal receiver for spectral line surveys!

4. What is a Line Survey? Typical Observations Individual, narrow frequency windows targeting only a handful of transitions. Line Survey A series of spectral windows pieced together to provide spectral coverage across a large frequency range.

5. Why Line Surveys? More lines observed more detection certainty Uniform coverage under similar instrument conditions minimizes calibration inconsistencies Comprehensive intensity information reliable model of physical conditions Broadband spectral coverage large amounts of info, and fast

6. Why New 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 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

7. The Orion KL Region http://oobleck.ifa.hawaii.edu:8080/where/images/orion.jpg Orion KL star forming region http://www.mpg.de/bilderBerichteDokumente/mul timedial/bilderWissenschaft/2009/02/Walter0902/ Web_Zoom.jpeg From Liu, S.-Y. et al. (ApJ 576, 2002) CSO Beam Size at  = 1 mm

8. Previous Orion KL Surveys >50 radio frequency Orion spectral line surveys reported in the literature! OVRO survey at = 1.3 mm 215 – 263 GHz RMS~ 150 mK 800 resolved spectral features 29 molecular species IDed

9. The Challenge: DSB Spectra + = Image sideband Observed Double Sideband Spectrum Frequency sideband desired line position Spectra from Nummelin et al. (ApJ Supp. Series 117, 1998) Lower SidebandUpper Sideband -IF +IF LO

10. Spectral Coverage on Orion

11. Initial Deconvolution of Orion Spectra Blake et al. OVRO survey: RMS = 150 mK, integration time ~ weeks (months?) Our survey: RMS = 30 mK, time ~ 4 nights

12. Line Identification Progress Total Lines >3  5548 Assigned Lines (to date)662 (11.9%) Unidentified Lines4886 (88.1%) Lines Assigned in Previous Surveys400 New Lines Assigned (to date)262

13. Line Identification Progress MoleculeLines Previously ObservedNew Lines Observed CO20 DNC10 C 17 O10 H 2 CO10 CH 3 CCH50 CH 3 13 CN20 HNCO30 C 33 S10 HDO21 CN111 CH 3 CN201 13 CS11 C 34 S11 H 2 CS72 13 CH 3 CN73 CH 2 CO45 HCOOH76 C 2 H 5 CN6022 CH 3 OH5542 13 CH 3 OH1142 CH 3 CHO446 CH 3 OCH 3 2061

14. Line Identification

15. Next Steps? Orion Survey Analysis Finalize spectral deconvolution incorporate baseline subtraction, test for “ghosts” Analyze spectral information determine lineshapes, intensities Identify more lines from previously detected molecules include weak lines, isotopologues, vibrational states Rotational diagram analysis for each molecule account for multiple sources, velocities, temperatures Beyond the Orion Survey Line surveys of other sources completed: Sgr B2(N-LMH), NGC 1333-IRAS 4, L1157 upcoming: W51 e1/e2, G34.3+0.2, W3(H 2 O) & W3(OH) Laboratory spectroscopic studies Comparison to astrochemical models ID of new molecules only after complete simulation of known molecules is achieved

16. 1 – 50 GHz Frequency Synthesizer VDI Multiplier chain 50 GHz – 1.2 THz Detector Gas Flow Cell To Computer Sample InputTo Vacuum Pump Laboratory Spectral Cataloging Methanol Broadband Scan Dimethyl Carbonate (CH 3 OCOOCH 3 ) First light April 1, 2009!

17. Acknowledgements The Widicus Weaver Group: Mary Radhuber Jay Kroll Brandon Carroll Jake Laas Thomas Anderson John Pearson & Brian Drouin @ JPL CSO Local Staff