A short overview
The goal of project A5 is to investigate the star formation conditions as well as the impact and feedback of star formation on the interstellar medium (ISM) in the extreme environment of the Galactic Center molecular clouds. The project characterizes the physical and chemical properties of these clouds from several degree scales, including the Central Molecular Zone, to small scales of objects such as the „mini-starburst“ Sgr B2 and the central nuclear disk. As diagnostics, bright ISM cooling lines and transitions from selected chemical species are observed and physical and chemical models are used to constrain the conditions in the Galactic Center clouds.
Being the closest central region of a galaxy we can observe and due to the high degree of star formation activity in the recent past and its chemical richness, the Galactic Center is a unique test case for star formation conditions in galactic nuclei. Observations within project A5 comprise large scale mapping of the bright ISM cooling lines, together with extensive mapping in a selected set of spectral lines within the Central Molecular Zone, and detailed investigations of special regions, such as Sgr B2 and Sgr A* or the Giant Molecular Loops. Based on these observations, the kinetic temperature of a large part of the Galactic Center could already be determined, as well as the spatial distribution of various chemical species. The Galactic Center and its Central Molecular Zone will be a dedicated target for large scale heterodyne mapping with the CHAI receiver on CCAT-prime in the near future.
Project A5 has substantial overlap with the Galactic and extragalactic astronomical projects A1, A2, and in particular with A3, A4, and A6 as the Galactic Center constitutes the link between Galactic clouds and extra-galactic nuclei. There is considerable overlap with B3 and B2 for dense, quiescent clouds of the region, and the detailed line surveys require the use of spectroscopic databases as developed by the Cologne laboratory astrophysics. The analysis and interpretation of the observations rely on the modeling efforts in C1, C3, C5, and the new project C6 (large scale UV impact in PDRs and shocks (e.g., winds and cloud-cloud collisions), comparison to simulations and observations of simulated clouds). The strong demands imposed by spectroscopic observations towards the Galactic Center immediately result in requirements for instrumentation, as developed in project groups D and service project S.
Large scale mapping: We will investigate the physical conditions and chemistry of the large scale Galactic Center cloud systems, including the full extent of the Central Molecular Zone (CMZ), over a range of several square degrees through mapping observations of the bright ISM cooling lines of CO, CI, CII, NII, and OI. These observations will be the basis for modelling of the emission (excitation, PDR chemistry, large scale UV impact, XDRs, high energy particles and secondaries, shocks).
Central Molecular Zone: We plan to explore the chemical peculiarity and richness of the clouds in the Central Molecular Zone with extensive mapping in a selected set of spectral lines from a variety of molecules that are present with large spatial extent, such as formaldehyde, ammonia, and one of the most widespread molecules, methanol.
Detailed investigation of special regions: On smaller scales, we will address the very special conditions in the mini-starburst region Sgr B2 (together with projects A6 and B3) and the nuclear disk (CND) around the central supermassive black hole Sgr A*. As diagnostics, we will conduct observations of bright ISM cooling lines and multi-species/multi-transition studies from various molecules.
These data together with our modelling will provide a comprehensive view of the conditions and processes in these regions whose physics and chemistry are intrinsically connected. In particular, we shall study the impact and feedback of local star formation and shall examine the influence of processes involving very high energies.
- D. Riquelme, A. Amo-Baladron, J. Martin-Pintado, R. Mauersberger, S. Martin, M. Burton, M. P. Jones, K. M. Menten, L. Bronfman, and R. Güsten, “The foot points of the Giant Molecular Loops in the Galactic center region”, A&A, in press, ArXiv:1710.09613 (2018)
- D. Riquelme, L. Bronfman, R. Mauersberger, R. Finger, C. Henkel, T. L. Wilson, and P. Cortés-Zuleta, “The diffuse molecular component in the nuclear bulge of the Milky Way”, A&A 610, A43 (2018)
- J. Kauffmann, T. Pillai, Q. Zhang, K. M. Menten, P. F. Goldsmith, X. Lu, and A. E. Guzmán, “The Galactic Center Molecular Cloud Survey. I. A steep linewidth-size relation and suppression of star formation”, A&A 603, A89 (2017)J.
- Kauffmann, T. Pillai, Q. Zhang, K. M. Menten, P. F. Goldsmith, X. Lu, A. E. Guzmán, and A. Schmiedeke, “The Galactic Center Molecular Cloud Survey. II. A lack of dense gas and cloud evolution along Galactic center orbits”, A&A 603, A90 (2017)
- P. García, R. Simon, J. Stutzki, R. Güsten, M. A. Requena-Torres, and R. Higgins, “Warm ISM in the Sagittarius A Complex. I. Mid-J CO, atomic carbon, ionized atomic carbon, and ionized nitrogen sub-mm/FIR line observations with the Herschel-HIFI and NANTEN2/SMART telescopes”, A&A 588 , A131 (2016)
- A. Ginsburg, C. Henkel, Y. Ao, D. Riquelme, J. Kauffmann, T. Pillai, E. A. C. Mills, M. A. Requena-Torres, K. Immer, L. Testi, J. Ott, J. Bally, C. Battersby, J. Darling, S. Aalto, T. Stanke, S. Kendrew, J. M. D. Kruijssen, S. Longmore, J. Dale, R. Güsten, and K. M. Menten, “Dense gas in the Galactic central molecular zone is warm and heated by turbulence”, A&A 586, A50 (2016)
- K. Immer, J. Kauffmann, T. Pillai, A. Ginsburg, and K. M. Menten, “Temperature structures in Galactic center clouds. Direct evidence for gas heating via turbulence”, A&A 595, A94 (2016)
- A. Ginsburg, A. Walsh, C. Henkel, P. A. Jones, M. Cunningham, J. Kauffmann, T. Pillai, E. A. C. Mills, J. Ott, J. M. D. Kruijssen, K. M. Menten, C. Battersby, J. Rathborne, Y. Contreras, S. Longmore, D. Walker, J. Dawson, and J. A. P. Lopez, “High-mass star-forming cloud G0.38+0.04 in the Galactic center dust ridge contains H2CO and SiO masers”, A&A 584, L7 (2015)
- N. Harada, D. Riquelme, S. Viti, I. Jiménez-Serra, M. A. Requena-Torres, K. M. Menten, S. Martín, R. Aladro, J. Martin-Pintado, and S. Hochgürtel, “Chemical features in the circumnuclear disk of the Galactic center”, A&A 584, A102 (2015)
- J. S. Zhang, L. L. Sun, D. Riquelme, C. Henkel, D. R. Lu, Y. Zhang, J. Z. Wang, M. Wang, and J. Li, “Isotopic Ratios of 18O/17O in the Galactic Central Region”, ApJS 219, 28 (2015)
- Belloche, A.; Müller, H. S. P.; Menten, K. M.; Schilke, P.; Comito, C., Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M), 2013, A&A 559, 47
- Ao, Y.; Henkel, C.; Menten, K. M.; Requena-Torres, M. A.; Stanke, T.; Mauersberger, R.; Aalto, S.; Mühle, S.; Mangum, J., The thermal state of molecular clouds in the Galactic center: evidence for non-photon-driven heating, 2013, A&A 550, 135
- Immer, K.; Menten, K. M.; Schuller, F.; Lis, D. C., A multi-wavelength view of the Galactic center dust ridge reveals little star formation, 2012, A&A 548, 120
- Ordu, M. H.; Müller, H. S. P.; Walters, A.; Nuñez, M.; Lewen, F.; Belloche, A.; Menten, K. M.; Schlemmer, S., The quest for complex molecules in space: laboratory spectroscopy of n-butyl cyanide, n-C4H9CN, in the millimeter wave region and its astronomical search in Sagittarius B2(N), 2012, A&A 541, 121
- Jones, P. A.; Burton, M. G.; Cunningham, M. R.; Requena-Torres, M. A.; Menten, K. M.; Schilke, P.; Belloche, A.; Leurini, S.; Martín-Pintado, J.; Ott, J.; Walsh, A. J., Spectral imaging of the Central Molecular Zone in multiple 3-mm molecular lines, 2012, MNRAS 419, 2961
- Immer, K.; Schuller, F.; Omont, A.; Menten, K. M., Recent star formation in the inner Galactic bulge seen by ISOGAL. II. The central molecular zone, 2012, A&A 537, 121
- Requena-Torres, M. A.; Güsten, R.; Weiß, A.; Harris, A. I.; Martín-Pintado, J.; Stutzki, J.; Klein, B.; Heyminck, S.; Risacher, C., GREAT confirms transient nature of the circum-nuclear disk, 2012, A&A 542, 21
- Brünken, S.; Belloche, A.; Martín, S.; Verheyen, L.; Menten, K. M., Interstellar HOCN in the Galactic center region, 2010, A&A 516, 109
- Garcia, P.; Simon, R.; Stutzki, J.; Requena-Torres, M.; Güsten, R.; et al., The Warm ISM in the Sgr A Region: Mid-J CO, Atomic Carbon, Ionized Atomic Carbon, and Ionized Nitrogen Line Observations with the HERSCHEL/HIFI and NANTEN2/SMART Telescopes, 2014, Proceedings IAU Symposium No. 303 “The Galactic Center: Feeding and feedback in a normal galactic nucleus”
- Harada, N, Riquelme, D., Viti, S., Menten, K., et al., Molecules in the Circumnuclear Disk of the Galactic Center., IAU Symp. 303, 2013, in press; arXiv1312.1905
Prof. Karl Menten (PI, MPIfR), Dr. Robert Simon (PI, PH1), Dr. Denise Riquelme (MPIfR), Dr. Christian Henkel (MPIfR), Dr. Pablo Garcia (CASSACA, Chile), Dr. Rolf Güsten (MPIfR), Dr. Ronan Higgins (PH1), Prof. Jürgen Stutzki (PH1), Dr. Helmut Wiesemeyer (MPIfR), Arshia Maria Jacob (MPIfR), Martin Steinke (PH1)