Disk-Halo interface: The "foot point" of the Galactic Molecular Loops
D. Riquelme, M. A. Amo-Baladron, J. Martin-Pintado, R. Mauersberger, L. Bronfman, S. Martin
aa r X i v : . [ a s t r o - ph . GA ] F e b **FULL TITLE**ASP Conference Series, Vol. **VOLUME**, **YEAR OF PUBLICATION****NAMES OF EDITORS** Disk-Halo interface: The “foot point” of the GalacticMolecular Loops
D. Riquelme , M. A. Amo-Baladr´on , J. Mart´ın-Pintado , R.Mauersberger , L. Bronfman , S. Mart´ın Abstract.
We study the disk-halo interaction, in the context of orbits andGiant Molecular loops (GMLs) in the Galactic center (GC) region. We present alarge scale survey in the central kpc in SiO(J=2-1), HCO + (J=1-0) and H CO + (J=1-0), observations in 3mm lines toward a region in two clumps M+5.3-0.3and M-3.8+0.9 placed in the foot point of two molecular loops, and observationstoward selected positions, to trace accretion of the gas from the halo. • A large scale survey of the GC region in the J=2-1 transition of SiO and theJ=1-0 transition of HCO + and H CO + (FWHM=3.6’) was conducted us-ing the NANTEN telescope to study cloud conditions, heating mechanismsand chemistry (Riquelme et al. 2010). The observed region covers an areabetween − o . < l < o .
625 and − o . < b < o . + line intensity ratio is found at the ”foot points” of the GMLs (Fukui et al.2006) and toward the 1 o . • Higher spatial resolution (FWHM=38”) observations of 3mm lines wereperformed toward selected regions of two PMZ cloud: M-3.8+0.9 andM+5.3-0.3, using the Mopra telescope. The maps reveal structures atsmall scales in the SiO emission, an evidence of the presence of shocks(Mart´ın-Pintado et al. 1992, 1997). Both mapped clumps show large dif-ferences between the spatial distribution of the SiO and the HCO + emis-sion, which indicates differences in the chemistry and physical propertieswithin the clumps. The SiO emission in the M-3.8+0.9 cloud presents nar-row profiles (20 km/s) in comparison with the HCO + profiles (50 km/s, seeFig. 1), thus, shocked gas is dynamically more confined than the HCO + .Also remarkable is the decrease of the HNCO emission that we find in theM+5.3-0.3 cloud as compared with the M-3.8+0.9 cloud. Mart´ın et al.(2008) claim that the HNCO molecule is easily photodissociated by UVradiation. Therefore, it might be possible that stellar winds produced by Instituto de Radioastronom´ıa Milim´etrica (IRAM), Av. Divina Pastora 7, Local 20, E-18012Granada, Spain Centro de Astrobiolog´ıa (CSIC/INTA), Ctra. de Torrej´on a Ajalvir km 4, E-28850, Torrejonde Ardoz, Madrid, Spain Joint ALMA Observatory, Av. El Golf 40, Piso 18, Las Condes, Santiago de Chile, Chile Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago de Chile, Chile Riquelme et al
Nanten Mopra
C) B)A) SiOHCO+ −70 to −40 km/sHCO+ SiO−100 to −70 km/s
MopraNanten
110 to 140 km/s70 to 110 km/sC) B)A)
Figure 1.
Left: A) Integrated intensity map of SiO emission in M-3.8+0.9. B) Mopraobservations. Top: Integrated intensity map from -110 to -70 km/s in SiO (right) andHCO + (left). Bottom: Integrated intensity map from -70 to -40 km/s in SiO (right) andHCO + (left). C) Composite spectra over a region of 1.8 × + , SiO, HNCO.Right: A) Integrated intensity map of SiO emission of M+5.3-0.3. B) Mopra observation.Top: Integrated intensity map from 70 to 110 km/s in SiO(left) and HCO + (right). Bottom:Integrate intensity map from 110 to 140 km/s in SiO(left) and HCO + (right). C)Compositespectra over a region of 1.9 × + , SiO, HNCO. star clusters in the disk could play a role in the generation of the shocksin the molecular cloud M+5.3-0.3. • The C/ C isotopic ratio reflects the relative degree of primary to sec-ondary processing in stars. C is formed on rapid time scale in intermedi-ate and high-mass stars, whereas C is produced primarily via CNO pro-cessing of C seeds from earlier stellar generation, in a lower time scale inlow and intermediate mass stars or novae. Using the IRAM 30m telescope,we measure this isotopic ratio in 7 selected positions (Riquelme et al.2010), 5 toward the disk-halo interaction sites (3 in the GMLs and 2 in thex -x orbits interaction places (Binney et al. 1991)), and 2 in the Galacticplane tracing “standard” GC gas. Our preliminary results clearly point toa higher C/ C isotopic ratios (50 −
70) toward the positions and veloc-ity components associated with disk-halo interaction sites, compared withthe “standard” GC values (20 − References
Binney, J., Gerhard, O. E., Stark, A. A.,et al. 1991,
MNRAS , 252, 210Bitran, M., Alvarez, H., Bronfman, L., et al. 1997,
A&AS , 125, 99Fukui, Y.,Yamamoto, H., Fujishita, M. et al. 2006, Science, 314, 106Mart´ın, S., Requena-Torres, M. A., Mart´ın-Pintado, J., et al. 2008,
ApJ , 678, 245Mart´ın-Pintado, J., Bachiller, R., & Fuente, A. 1992,
A&A , 254, 315Mart´ın-Pintado, J., de Vicente, P., Fuente, A., & Planesas, P. 1997,