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Millimeter-Wave Molecular Line Observations of the Galactic Circumnuclear Disk Shunya Takekawa T. Oka, K. Tanaka, K. Miura, H. Suzuta Keio University.

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Presentation on theme: "Millimeter-Wave Molecular Line Observations of the Galactic Circumnuclear Disk Shunya Takekawa T. Oka, K. Tanaka, K. Miura, H. Suzuta Keio University."— Presentation transcript:

1 Millimeter-Wave Molecular Line Observations of the Galactic Circumnuclear Disk Shunya Takekawa T. Oka, K. Tanaka, K. Miura, H. Suzuta Keio University

2 Rotating velocity: ~ 110 km/s Density: ~ 10 4–6 cm –3 Mass: ~ 10 4–5 M ☉ The entity of the CND is possibly an infalling disk with a diameter of 10 pc (e.g. Oka et al. 2011) contour: 5 GHz continuum The Galactic Circumnuclear Disk 2 pc radius ring (CND) HCN 1–0

3 blue shift (V LSR = –80 – –110 km/s) Rotating velocity: ~ 110 km/s Density: ~ 10 4–6 cm –3 Mass: ~ 10 4–5 M ☉ The entity of the CND is possibly an infalling disk with a diameter of 10 pc (e.g. Oka et al. 2011) contour: 5 GHz continuum The Galactic Circumnuclear Disk 2 pc radius ring (CND) HCN 1–0 red shift (V LSR =+80 – +110 km/s) Single-dish obs. CO 1–0 (Serabyn et al. 1986) ~ 10 pc Sgr A* mostly neglected!

4 The Galactic Circumnuclear Disk How is the CND affected by nuclear activities? How does the CND feed the nucleus? How was the CND formed? How is the physical condition? etc…

5 The Galactic Circumnuclear Disk In order to answer these questions, it is essential to reveal the accurate distribution.

6 The Galactic Circumnuclear Disk In order to answer these questions, it is essential to reveal the accurate distribution. SINGLE DISH! ASTE 10 m NRO 45 m

7 The Galactic Circumnuclear Disk In order to answer these questions, it is essential to reveal the accurate distribution. SINGLE DISH! appropriate tracer + + ASTE 10 m NRO 45 m

8 To search appropriate tracers of the CND, We conducted 3 mm band spectral line surveys toward the CND and Sgr A* with the NRO 45 m. (Takekawa et al. 2014) TZ1 receiver + SAM45 frequency : 81 – 116 GHz resolution : 15” –19” 50 lines were detected

9 We classified the detected lines into three types: – CND-type: mainly trace the CND – GMC-type: mainly trace the GMCs (50 km/s and 20 km/s clouds) – HBD-type: hybrid between the CND- and GMC-types

10 We classified the detected lines into three types: – CND-type: mainly trace the CND – GMC-type: mainly trace the GMCs (50 km/s and 20 km/s clouds) – HBD-type: hybrid between the CND- and GMC-types HCO + HCN SiO CN H 13 CO + H 13 CN N2H+N2H+ CH 3 OH HC 3 N CS SO C2HC2H c-C 3 H 2

11 We classified the detected lines into three types: – CND-type: mainly trace the CND – GMC-type: mainly trace the GMCs (50 km/s and 20 km/s clouds) – HBD-type: hybrid between the CND- and GMC-types HCO + HCN SiO CN H 13 CO + H 13 CN N2H+N2H+ CH 3 OH HC 3 N CS SO C2HC2H c-C 3 H 2 OTF mapping of the CND

12 The OTF mapping of the CND with the NRO 45 m date: 2014/2/5 – 2/12, 3/28 – 3/30 (33 hr) line: HCN 1–0, HCO + 1–0, SiO 2–1, CS 2–1, etc… mapping range: 6’×6’ angular resolution: ~ 19” receiver: TZ1 H/V spectrometer: SAM45 – bandwidth: 1 GHz (resolution: kHz)

13 Result HCN 1–0 integrated intensity map 2-pc ring Negative Longitude Extension +50 km/s cloud +20 km/s cloud

14 The velocity structure V LSR = –150 〜 +150 km/s HCN 1–0

15 The velocity structure V LSR = –150 〜 +150 km/s –150 〜 –20 km/s, +80 〜 +150 km/s HCN 1–0

16 C1 cloud and Negative Longitude Extension (NLE) –150 〜 –20 km/s, +80 〜 +150 km/s V LSR = –150 〜 –20km/s HCN 1–0

17 C1 cloud and Negative Longitude Extension (NLE) –150 〜 –20 km/s, +80 〜 +150 km/s V LSR = –150 〜 –20km/s first reported in Oka et al HCN 1–0 mostly neglected in recent studies!

18 New discovery 1

19 A velocity structure of the C1 cloud V LSR = –150 〜 –20km/s HCN 1–0 New discovery 1

20 A velocity structure of the C1 cloud V LSR = –150 〜 –20km/s HCN 1–0 CS 2–1 New discovery 1

21 A velocity structure of the C1 cloud V LSR = –150 〜 –20km/s HCN 1–0 CS 2–1 The C1 cloud is associated with the CND! CND C1 cloud New discovery 1

22 New discovery 2

23 A streamer from the +20 km/s cloud to the CND V LSR = –150 〜 –20km/s HCN 1–0 CS 2–1 New discovery 2

24 A streamer from the +20 km/s cloud to the CND V LSR = –150 〜 –20km/s HCN 1–0 CS 2–1 +20 km/s cloud CND New discovery 2

25 A streamer from the +20 km/s cloud to the CND V LSR = –40 〜 +10km/s CS 2–1 +20 km/s cloud CND New discovery 2

26 A streamer from the +20 km/s cloud to the CND V LSR = –40 〜 +10km/s CS 2–1 +20 km/s cloud CND A streamer feeding the CND from the +20 km/s cloud New discovery 2

27 CND A streamer from the +20 km/s cloud to the CND V LSR = –40 〜 +10km/s CS 2–1 +20 km/s cloud ★ The +20 km/s cloud may be feeding the CND through the NLE A possible scheme of the central environment seen from the Galactic north pole +50 km/s cloud molecular ridge +20 km/s cloud to observer 2-pc ring NLE streamer CND New discovery 2

28 Conclusion We found that 1.The C1 cloud is associated with the CND 2.The +20 km/s cloud may be feeding the CND through the NLE Single dish observations are very important for studies of the CND! HCN 1–0 V LSR = –150 〜 –20km/s A possible scheme of the central environment

29 Future works Detailed analysis – line ratios – estimation of physical parameters We have already obtained the J =4–3 lines of HCN and HCO + using the ASTE 10 m Data reduction of the ASTE observations – We have conducted spectral line surveys in 330 – 360 GHz band with the ASTE 10 m HCN 4–3HCN 1–0 Using the single-dish data, we will make efforts to reveal the actual entity of the CND

30 Summary We conducted the OTF mapping observations of the Galactic CND with the NRO 45 m We found that 1.The C1 cloud is associated with the CND 2.The +20 km/s cloud may be feeding the CND through the NLE Single dish observations are very important for studies of the CND! HCN 1–0 A possible scheme of the central environment


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