ASTROCHEMISTRY IN THE SUBMM DOMAIN Bérengère Parise With kind inputs from my MPIfR colleagues: A. Belloche, S. Leurini, P. Schilke, S. Thorwirth, F. van der Tak APEX, opening the way for ALMA Paris, February 3rd, 2006

APEX, opening the way for ALMA - Paris, Feb 3rd Visible Ultraviolet electronic transitions Infrared Submillimetre Millimetre Radio vibrational transitions rotational transitions Molecular emission Submm : ground rotational transitions of light molecules and excited rotational transitions of heavier molecules. The lighter the molecule, the higher the frequencies. The electromagnetic spectrum What does submillimetre bring to astrochemistry ? Astrochemistry : study of the synthesis of molecules in space and their use in determining the properties of interstellar medium.

APEX, opening the way for ALMA - Paris, Feb 3rd Submm : which molecules ? which environments ? Ground transitions of light molecules --> probe mostly cold regions Higher excitation lines of heavier molecules --> probe warmer and/or denser regions Spectral surveys an insight into molecular complexity comparing the chemical properties of different sources H 2 D +, HD 2 + essential for deuterium chemistry HDO probe water content from the ground H 3 O + CR ionization rate CF + PDR tracer CO, SiO outflows

APEX, opening the way for ALMA - Paris, Feb 3rd Deuterium chemistry : H 2 D + and D 2 H + H HD --> H 2 D + + H 2 Reverse reaction slightly endothermic : at low T, H 2 D + /H 3 + » HD/H 2 ~ H 2 D + : ortho state (372 GHz) --> APEX2a receiver para state (1370 GHz) D 2 H + : ortho state (1477 GHz) para state (692 GHz) --> CHAMP+ main reservoir of D in molecular clouds Ions responsible for the transfer of deuterium in molecules Their ground transitions lie in the submillimetre regime : In some cold and depleted environments, they can be among the most abundant ions : - depleted prestellar cores ( Caselli et al. 2003, Walmsley et al. 2004: tracer of kinematics, Vastel et al ) - midplane of disks ( Ceccarelli et al. 2004: tracer of ionization degree ) CONDOR receiver

APEX, opening the way for ALMA - Paris, Feb 3rd Deuterium chemistry : H 2 D +, N 2 D +, DCO + Belloche et al., in prep APEX observations towards the southern prestellar condensation Cha-MMS1 T sys is two to three times better than at JCMT/CSO

APEX, opening the way for ALMA - Paris, Feb 3rd HDO : tracing water from the ground Water can only be observed from space. Observation of HDO : - probe the water content of astronomical sources from the ground (better spatial resolution than satellites). - link between material in protostellar envelopes, disks, comets, oceans... Energy (cm -1 ) APEX will allow observation of the two ground transitions of HDO : 464 GHz, FLASH receiver 893 GHz, CHAMP+ receiver IRAM 30m HSO/HIFIAPEX/FLASHAPEX/CHAMP+ HDO

APEX, opening the way for ALMA - Paris, Feb 3rd H 3 O + : constraining CR ionization rate van der Tak et al. in prep H 3 O + 364GHz H 2 183GHz Sgr B2 Cernicharo et al. ApJ in press APEX observations H 3 O + /H 2 O + chemical model --> ionization rate Can further be compared to HCO + /CO diagnostic

APEX, opening the way for ALMA - Paris, Feb 3rd CF + first detection : a PDR tracer Theoretical studies ( Neufeld, Wolfire & Schilke 2005 ) have shown: - HF main reservoir of F - HF is abundant even close to UV irradiated cloud surfaces where C + is the dominant reservoir of C - HF + C + --> CF + + H Gas abundances in a one-sided PDR with n H = 10 2 cm -3 and  UV = 1 Neufeld et al. A&A 2006 in press Observations towards the Orion Bar

APEX, opening the way for ALMA - Paris, Feb 3rd High energy lines of CO : outflows Excitation computation becomes possible with observations of high energy CO lines --> physical parameters : n, T Leurini et al. in prep APEX observations NGC6334I high-velocity outflow

APEX, opening the way for ALMA - Paris, Feb 3rd Unbiased spectral surveys and 818GHz NGC6334I (black) and G (red) Schilke et al. in prep An insight into molecular complexity A tool to compare chemical properties of different environments : evolution signatures ? differences between low and high-mass hot cores ? FLASH observations

APEX, opening the way for ALMA - Paris, Feb 3rd Summary Observation of molecules is a powerful tool to probe not only the chemistry but also the physical conditions in astronomical sources. The submillimetre range is an essential domain for these studies.