Spectral Line Surveys with the CSO Susanna L

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

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

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 Receivers Tsys (K, SSB) Spectral (IF) Bandwidth (GHz) 120 1 Z-Rex 100 4 Z-Rex is an ideal receiver for spectral line surveys!

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.

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

Why New Molecular Line Surveys? • 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, Ap. J 682, 2008 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

The Orion KL Region Orion KL star forming region http: //www. mpg. de/bilder. Berichte. Dokumente/multi medial/bilder. Wissenschaft/2009/02/Walter 0902/We b_Zoom. jpeg http: //oobleck. ifa. hawaii. edu: 8080/where/images/orion. jpg CSO Beam Size at l = 1 mm From Liu, S. -Y. et al. (Ap. J 576, 2002)

Previous Orion KL Surveys >50 radio frequency Orion spectral line surveys reported in the literature! OVRO survey at l = 1. 3 mm 215 – 263 GHz RMS~ 150 m. K 800 resolved spectral features 29 molecular species IDed

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

Spectral Coverage on Orion

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

Line Identification Progress Total Lines >3 s 5548 Assigned Lines (to date) 662 (11. 9%) Unidentified Lines 4886 (88. 1%) Lines Assigned in Previous Surveys 400 New Lines Assigned (to date) 262

Line Identification Progress Molecule CO DNC C 17 O H 2 CO CH 3 CCH CH 313 CN HNCO C 33 S HDO CN CH 3 CN 13 CS C 34 S H 2 CS 13 CH CN 3 CH 2 CO HCOOH C 2 H 5 CN CH 3 OH 13 CH OH 3 CH 3 CHO CH 3 OCH 3 Lines Previously Observed 2 1 1 1 5 2 3 1 2 11 20 1 1 7 7 4 7 60 55 11 4 20 New Lines Observed 0 0 0 0 1 1 1 2 3 5 6 22 42 42 46 61

Line Identification

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 B 2(N-LMH), NGC 1333 -IRAS 4, L 1157 upcoming: W 51 e 1/e 2, G 34. 3+0. 2, W 3(H 2 O) & W 3(OH) • Laboratory spectroscopic studies • Comparison to astrochemical models • ID of new molecules only after complete simulation of known molecules is achieved

Laboratory Spectral Cataloging First light April 1, 2009! 1 – 50 GHz Frequency Synthesizer To Computer VDI Multiplier chain 50 GHz – 1. 2 THz Detector Gas Flow Cell Sample Input To Vacuum Pump Methanol Broadband Scan Dimethyl Carbonate (CH 3 OCOOCH 3)

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