GREAT

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

German Receiver for Astronomy at THz Frequencies ATM 1-5 THz, 14 km altitude

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

heterodyne receiver

GREAT is a heterodyne spectrometer for FIR (THz) astronomy

• as a spectrometer, GREAT analyses the frequency information carried

in the astronomical signal.

much as you tune your radio to the frequency of your favorite station, we

operate GREAT at selected frequencies of astronomical interests

!! all molecules, atoms have their characteristic frequency footprints !!

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

heterodyne principle

GREAT is a heterodyne spectrometer for FIR (THz) astronomy

Greek roots: hetero- "different", and dyn- "power" (cf. dynamis, dunamis)

• as a spectrometer, GREAT analyses the frequency information carried

in the astronomical signal.

much as you tune your radio to the frequency of your favorite channel, we

operate GREAT at selected frequencies of astronomical interests

!! all molecules, atoms have their characteristic frequency footprint !!

• switching on your radio, you listen to the „heterodyne principle“

which describes the generation of new frequencies by mixing two frequencies

applied to GREAT, this describes the down-

conversion from THz to GHz frequencies,

where the signal processing takes place.

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

Far-Infrared spectroscopy ?

GREAT is a heterodyne spectrometer for FIR (THz) astronomy

The FIR is the scientifically most promising, but so far widely underutilized

part of the electromagnetic spectrum

FIR is terra incognita because:

• lack of suitable technologies (but the „terahertz gap“ is slowly closing..)

• Earth‘s atmosphere efficiently absorbs THz photons from space. Science must be

performed from space or from high-flying platforms: SOFIA

extracted from www.sura.org

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

Why observe with SOFIA ?

In the stratosphere the atmosphere becomes transparent to most (not all) FIR

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

German REceiver for Astronomy at Terahertz frequencies

Channel Frequencies [THz] Astronomical lines of interest

low-frequency #1 1.25 – 1.50 [NII], CO(12-11), (13)

CO(13-12), HCN(17-16), H2D+

low-frequency #2 1.82 – 1.92 [CII], CO(16-15) mid-frequency 2.4 – 2.7 HD, OH(

23/2), CO(22-21),

(13)CO(23-22)

high-frequency 4.7 [OI]

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

Our first science flight

GREAT observed the fine-structure line of ionized carbon [CII] at 1.9 THz

and of warm carbon monoxid CO(13-12) at 1.5 THz towards M17SW, a

molecular cloud prominently forming new massive stars.

Press release on April 07

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

GREAT dips into cradle of star formation

CO J=11-10

Image: Spitzer/GLIMPSE 8 µm

G5.89 :

a cluster of massive

stars in the making

Cloud collapse is

associated with

energetic outflows

that can be studied

with GREAT/SOFIA

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

The circum-nuclear disk in the GC

carbon monoxid (CO) in orbit around the central mass

GREAT will help constraining the

physical conditions of the gas

reservoir, feeding the nucleus

a massive gas disk is rotating around & feeding the black hole in the Galactic center

CO(11-10) observed with GREAT

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

… the next frontier: HD 2.7 THz

While closing the THz gap! – we push GREAT into new territories, namely

spectroscopy beyond 2 THz

As we speak, our novel 2.7 THz detector is commissioned in the lab (tour)

Why is this so exciting?

because observations of hydrogen deuteride HD become possible

Well…

but: deuterium is only produced in the Big Bang, therefore does serve as chemical clock of the evolution of the universe

Our chemical networks tell us that HD is likely to be the

best tracer of the cold ISM (molecular hydrogen is not observable)

best tracer of the late star forming process (latest freeze-out)

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

Outlook and Ongoing Upgrades

while looking forward to our basic science flights in July & September

we are preparing for the next frequency extension: H-channel at 4.6 THz ([OI])

we have launched the instrument’s first major upgrade into a compact array:

upGREAT to operate simultaneously 14 pixels at 1.9-2.5 THz and 7 pixels at 4.7 THz

SOFIA Media Day - June 08, 2011

MPIfR KOSMA MPS

DLR-PF

R.Güsten

the GREAT consortium

Principal Investigator Project Management Co-Investigators

Rolf Güsten Stefan Heyminck (MPIfR) Jürgen Stutzki (KOSMA)

MPI für Radioastronomie Paul Hartogh (MPS)

Auf dem Hügel 69 Heinz-Wilhelm Hübers (DLR-PF)

53121 Bonn, Germany

[email protected]

For more information: http://www.mpifr.de/div/submmtech/heterodyne/great/greatmain.html

GREAT is developed by the Max-Planck-Institut für Radioastronomie and the Universität zu Köln, in collabo-

ration with the MPI for Solar System Research and the DLR Institute for Planetary Research, financed by the

participating institutes, the Max-Planck-Society and Deutsche Forschungsgemeinschaft, supported by DLR.