Terahertz Science Cases for the Greenland Telescope

Transcription

1 Terahertz Science Cases for the Greenland Telescope Hiroyuki Hirashita Satoki Matsushita, Patrick M. Koch ASIAA GLT Single Dish Science Discussion Group (ASIAA, Taiwan)

2 Topics 1. GLT Project 2. Opening First-Generation Ground- Based THz 3. Extragalactic Scientific Cases 4. Future Prospects

3 1. Greenland Telescope (GLT) Project ALMA-NA Prototype 12 m Antenna to be placed in Greenland Summit 3,200 m Main purpose: submm VLBI (imaging of the M87 black hole) starting around ASIAA, SAO, Haystack Observatory, and NRAO PI: P. Ho 12m - NA ALMA Socorro Greenland Summit 3200m current antenna status: - antenna disassembled 2012/ cold weather retrofit ongoing Picture provided by P. Koch

4 Single Dish Use of GLT Time suitable for VLBI is limited. Available for a large part of a year as a single dish! Taking advantage of good atmosphere and flexible time allocation (1) Opening a new wavelength: THz. (2) Time-consuming survey observations. (3) Monitoring. Beam ~ THz Similar resolution to SMA

5 Site Testing at Summit Station in Greenland water vapor radiometer at the site THz is accessible for ~ 10% of winter. K. Asada

6 Aim of This Talk (1) Clarify the science cases suitable for the first generation ground-based THz astronomy. (2) Make a firm step for the second generation science by larger telescopes such as CCAT.

7 2. Opening the First Generation Ground-Based THz Grand aim: Star formation Its Processes and Consequences

8 Warm Region Near to Forming Stars CONDOR (on APEX) Observations of Orion FIR 4 (Wiedner et al. 2006) S. Takakuwa Beam ~4.3 On-source 5.8 min Rms ~22 km s THz Compared to the mid-j lines, no ``Wing component CO (13-12) traces quiescent, very hot gas near the star.

9 Warm Region Near to Forming Stars CONDOR (on APEX) Observations of Orion FIR 4 (Wiedner et al. 2006) S. Takakuwa Beam ~4.3 On-source 5.8 min Rms ~22 km s THz Compared to the mid-j lines, no ``Wing component CO (13-12) traces quiescent, very hot gas near the star.

10 Toward Diffuse ISM Some basic molecules O. Morata [N II] 205 µm as SF indicator H. Hirashita Galactic H II regions: L(N II) = C L(Hα) Starting point for the local calibration of FIR finestructure line SF tracers THz 1.47 THz THz THz If we choose one band, the 1.5 THz window is preferred.

11 Merit of 1.5 THz Band for Continuum (Tdust) Tobs Adding THz really improves the temperature estimate. A shorter wavelength is better since it is nearer to the dust SED peak.

12 Tang et al. (2013) CSO THz Polarimetry (Dust) SMA P. Koch, H. Hirashita 4 arcsec resolution traces a medium-scale magnetic fields (between core and large scale) in THz. Polarization can distinguish the different components. 1.5 THz is the best. Based on Vaillancourt (2009)

13 First-Generation Key Science Opening the 1.5 THz Window Lines: (1) Warm region in the vicinity of newly formed stars by highly excited CO. (2) The diffuse ISM traced by CH or other molecular lines (starting point of the chemical reactions). (3) Local calibration of FIR star-formation indicators useful for high-z observations ([N II] 205 µm). Continuum (including polarization): The highest frequency (1.5 THz) gives the most independent information from the existing submm surveys. See Hsian-Hong Chang s talk for the development.

14 3. Extragalactic Scientific Cases

15 High-resolution (~ 4 arcsec) Nearby Galaxies H. B. Liu, S. Matsushita, H. Hirashita Nearby blue compact dwarfs variety of metallicities high-surface brightness (1) more precise dust mass (+SMA) (2) metallicity dependence of [N II] 205 µm Resolving interesting regions in nearby galaxies Interaction interface of X-ray outflow and molecular outflow

16 High-Redshift Galaxy Survey Beyond the Herschel confusion limit. (Bolometer) W.-H. Wang, H. Hirashita Dust Temperature 350 µm 450 µm 850 µm Total FIR luminosity Nguyen et al. (2010) Utilize the good atmospheric conditions at 350 and 450 µm Suitable for z ~ 1 2 normal- Tdust galaxies.

17 Making Use of Flexibility: Monitoring & ToO M. Nakamura, K. Asada Blasars Filling the gap at the Synchrotron self-absorption part. Gamma-Ray Bursts Y. Urata, K. Huang Abdo et al. (2011) Monitoring to trigger the VLBI observation: Identifying the location of the flare

18 4. Summary (1)GLT is a good opportunity for the first-generation ground-based THz science. (2)Starting with the 1.5 THz window gives the best strategy (basic lines + continuum/polarization). (3)Bolometer arrays at sub-thz is also useful for surveys. (4)Monitoring/ToO observations also provide new windows.

19 Thank you.

20 THz Lines S. Takakuwa

21 (2-d) High-z Spectral Lines Y.-T. Lin, W.-H. Wang [C II] at 1.9/(1 + z) THz: main coolant [N II] 2.5/(1 + z), 1.5/(1 + z) THz: tracer of ionized regions Wide-wavelength spectrometer in submm: z ~ 2: [C II] 633 GHz, [N II] 829 GHz, 487 GHz z ~ 3: [C II] 475 GHz, [N II] 614 GHz, 365 GHz Area > 500 deg 2 for baryonic acoustic oscillation to determine the cosmological parameters (nature of dark energy, initial non-gaussianity, neutrino mass). Maiolino et al. (2009)