[N II] 205 µm Science Cases for theGreenland Telescope
Hiroyuki Hirashita
Satoki Matsushita, Patrick M. Koch
ASIAA GLT Single Dish Science Discussion Group(ASIAA, Taiwan)

Topics
1. GLT Project
2. THz Science
3. [N II] 205 µm Surveys
4. Conclusion

1. Greenland Telescope (GLT) Project• ALMA-NA Prototype 12 m Antenna• To be placed in Greenland Summit Station @ 3,200 m• Main purpose: submm VLBI (imaging of the M87 blackhole) starting around 2016.
• ASIAA, SAO, Haystack Observatory, and NRAO
12m - NA ALMA prototype@ SocorroGreenlandSummit Station @ 3200mcurrent antenna status:- antenna disassembled 2012/2013- cold weather retrofit ongoingSite Testing at Summit Station in Greenland
THz is accessiblefor ~ 10% of winter.

tipping radiometer at the site

Martin-Cocher et al. (2014)

Day from 1 January 2011

Single Dish Use of GLTTime 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.
Matsushita et al. (1999)(2) Time-consuming surveys.
(3) Monitoring.

Beam ~ 4 arcsec @ 1.5 THz
Similar resolution to SMA

2. THz Science
Opening the 1.5 THz Window
Lines:(1) Vicinity of newly formed stars byhighly excited CO (S. Takakuwa).
(2) Simple molecules: starting point of
the chemical reactions (O. Morata).
(3) [N II] 205 µm as a SF indicator (H.
Hirashita).
Continuum (including polarization):
The highest frequency (1.5 THz) gives
the most independent information fromthe existing submm surveys (H. B. Liu,P. Koch, S. Matsushita, H. Hirashita).
CSOSMA3. [N II] 205 µm Surveys(1) Eion(N) > 13.6 eV ⇒ Exists only in H II regions. ⇒Good indicator of SFR (Inoue et al. 2014)?
(2) Metallicity dependence is also important to derive
metallicities in high-z galaxies by ALMA (Nagao et al.
2012).

[N II] 205 µm as a SF Indicator
Galactic H II regions:
L(N II) = C L(Hα) [or C’ L(radio)]Starting point for the local calibration of FIR finestructure line SF tracers.

Sensitivity: 190 Jy/beam (t/s)-1/2
with Δν = 107 Hz (Δv = 2 km s-1)

Carina I, IICar IICar I

Oberst et al. (2011)[N II]/Radio ratio provides a test for [N II] as a starformation indicator.
⇒ This ratio derived for Carina I, II is ten times smaller
than that expected from Inoue et al. (2014), probably
reflecting the peculiarity. ⇒ more samples by GLTNearby Galaxies
H. B. Liu, S. Matsushita, H. Hirashita

High-resolution (~ 4 arcsec)

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 regionsin nearby galaxies
Interaction interface of X-ray
outflow and molecular
outflowDetectability of Low-Metallicity BCDs
II Zw 40:
Expected flux from SFR + scaling with metallicity (Inoue2014)⇒ f([N II]) = 6.5 Jy/beam for II Zw 40with Δν = 108 Hz (20 km/s)
GLT: 1 σ 84 Jy/beam with Δν = 5 × 107 Hz (1 sec)
⇒ 1.1 h integration can detect [N II] in II Zw 40

4. Conclusion(1) GLT is targeting the 1.5 THz window, which has a richscience cases.
(2) [N II] 205 µm line is just in this window, and ispotentially important as a metallicity/SFR indicator.
(3) GLT can test the dependence on the SFR (Hα or radio)
in Galactic H II regions.
(4) The metallicity dependence is also addressed byobserving nearby low metallicity BCDs.

Thank you!

GLT History and Status

by boat to Thule- 2009: submm VLBI activity started at ASIAA- 2011: acquired NA ALMA prototype in collaboration
with CfA, MIT and NRAO
- 2011, August: site testing in Greenland started- 2011: investigations for retrofitting and relocation
to Greenland initiated- 2011-now: Vertex (Germany) main contractor
for antenna retrofit
ongoing efforts:- de-ice system- space frame- hexapod / nutator design- site infrastructure development

upcoming major milestones:- shipping from US to Thule military base- possible observations from Thule Base- traverse from Thule to Summit station

tractor traverse
from Thule to Summit

THz Lines
S. Takakuwa

(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 GHzz ~ 3: [C II] 475 GHz,[N II] 614 GHz, 365 GHz
Area > 500 deg2 for baryonic acoustic
oscillation to determine thecosmological parameters (nature ofdark energy, initial non-gaussianity,
neutrino mass).
Maiolino et al. (2009)