Millimeter Astronomy Linked to the Far-Infrared

MMiilllliimmeetteerr AAssttrroonnoommyy lliinnkkeedd ttoo tthhee FFaarr--IInnffrraarreedd

CCaarrsstteenn KKrraammeerr IIRRAAMM,, GGrraannaaddaa

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MM3333

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 AAnn eexxaammppllee:: TThhee nneeaarrbbyy ssppiirraall ggaallaaxxyy MM3333

Optical image (B,V,I,H) + 21cm line of HI in blue (Rector, Hanna 2005)

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThhee nneeaarrbbyy ssppiirraall ggaallaaxxyy MM3333

+ Morphological type: SA(s)cd

+ Major & minor diameters: 70.8, 41.7 arcmin

+ PA = 22.5 deg, Incl.: 55.0 deg

+ Distance = 840 kpc (180 kpc from M31)

+ 12 arcsec = 49 pc

+ Brightest HII complex in Local Group (NGC604)

+ Metallicity: subsolar by a factor 2-3 Shallow gradient

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThhee nneeaarrbbyy ssppiirraall ggaallaaxxyy MM3333

Location of Giant Molecular Clouds (GMCs) overlaid upon an integrated intensity map of the HI 21cm line (Engargiola et al. 2003). GMCs are formed from large structures of atomic gas.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 NNGGCC660033//MM3333

The HII region NGC603 in M33. (Optical image by HST)

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThhee IInntteerrsstteellllaarr MMeeddiiuumm iinn GGaallaaxxiieess

Phases of the Interstellar Medium and their main constituents and tracers:

HII Regions HII, NII, CII T~104K Warm Ionized Medium (WIM) HII, NII, CII n~10-3cm-3, T~105K Warm Neutral Medium (WNM) HI, CII n~0.3cm-3, T~8000K Cold Neutral Medium (CNM) HI, CII n~40cm-3, T~70K Dense Molecular Clouds H , CII, CI, CO n~103-6cm-3, T~10-100K 2 All stars form inside molecular clouds ! McKee & Ostriker 1977, Wolfire et al. 2003 Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TTOOCC

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 IInnttrroodduuccttiioonn ttoo MMiilllliimmeetteerr AAssttrroonnoommyy TTaabbllee ooff CCoonntteennttss

I. An example: The nearby galaxy M33: Star formation and dense gas

II. Tools of Millimeter Astronomy

II-1 Molecular and atomic lines II-2 Dust Emission

III. Telescopes: IRAM-30m & Herschel Space Observatory

IV. Far Infrared lines

V. Sources at high redshift

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuulleess && AAttoommss

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TToooollss ooff MMiilllliimmeetteerr AAssttrroonnoommyy

+ Molecular clouds are best studied at millimeter and far infrared wavelengths (3mm to 10m)

+ Observations at visible, UV, or soft X-ray wavelengths are hindered by dust extinction

+ In the continuum, thermal emission from dust particles dominates over Bremsstrahlung and synchrotron emission

+ Spectroscopy of atomic and molecular transitions allow detailed studies of physical conditions (density, temperature, mass, magnetic field,...) abundances [X/H], structure of the ISM and its dynamics (velocity fields)

+ More than 150 molecules have been detected in the ISM and in circumstellar envelopes to date.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuulleess iinn tthhee IISSMM aanndd iinn sshheellllss ((MMaayy 0099)) from the Cologne Data Base for Molecular Spectroscopy (CDMS)

>150 molecules

ongoing research

+laboratory work Benzene C H : 6 6 organic chemistry but also S,P,F,Cl,Fe,...

(Cernicharo et al. 2007 with ISO) kations and also few anions! Ethyl-formate C H OCHO: 2 5 Many radicals like CH, C H, OH, HCO, CN, ... 2

fairly complex (Belloche et al. 2009 with the 30m) molecules like Benzene, ... Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss

Orion

CO CN CH SiO CS SO 2 HNC HC N 3 CH OH 3 ...

3mm spectrum of the Orion Irc2 massive star forming region taken during commissioning of the new 30m receiver EMIR. Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss && AAttmmoosspphheerree

Atmosphere: +Transmission +“Windows” +H O, O , + ... 2 2 +Models

Molecular lines: +CO, HCN, HCO+,... +Transitions +Spacing

Atmospheric zenith transmission, T=exp(-), in the frequency range accessible to the IRAM 30m telescope

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 HH OO:: IInntteerreessttiinngg && hhaarrdd ttoo oobbsseerrvvee 2

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 HH OO:: hhaarrdd ttoo oobbsseerrvvee,, bbuutt ppoossssiibbllee!! 2

183GHz 325GHz

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss

E = E + E + E tot el vib rot

Assumes decoupling of nuclear and electronic motions (Born-Oppenheimer approx.) E ~ 104 cm-1 is the binding energy at equilibrium seperation of 1Angs. of the nuclei. el

Diatomic Molecules. E=kT=h=hc/ -1 Vibrational Energy: 1 cm = 30 GHz = 1.44 K = 1.24e-4 eV E ~ h (v+1/2) with v=0,1,2,... vib  h ~ 102-103 cm-1 vibrational bands v = +/-1 lie near 3 to 10m.

Rotational Energy: E ~ B J (J+1) with J=0,1,2,.. and the rotational constant B =h2/I with rot e e the moment of inertial I=2 R 2 with the reduced mass m=m m /(m +m .  e 1 2 1 2 E ~ 1 cm-1 rot

If the molecule has a permanent electric dipole moment, electric dipole transitions are allowed, with J = +/-1.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss

Rotational Energy (continued):

CO, HCN, CS have ~7m and J=1-0 transition at a wavelength of a few mm.  H OH, CH, HCl have ~m and J=1-0 transition in the submm/fir range.  H

H has no electric dipole moment. Only weak quadrupole transitions are allowed. 2 The lowest pure rotational transition of H between J=2-0 lies at 28 m. 2 

Higher order effects make spectra more complicated: +Anharmonicity of the potential for vibrations, +Centrifugal distortion for rotations, +Coriolis forces couple rotational and vibrational motion.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss

Polyatomic Molecules.

Non-linear, polyatomic molecules have 3 axes of rotation

If the molecule has a three-fold (or greater) symmetry axis, the moments of inertia of two of the three principle axes must be identical. The molecule is called symmetric top. Prolate case: I

Examples are:

Ammonia NH , Acetronitrile CH CN, Methylacetylene CH CCH. 3 3 3

Because of symmetry, two quantum numbers only: J, K Selection rules for radiative transitions: J=+/-1, K = 0. Possible further split-up of transitions: inversion (symmetric/antisymmetric nuclear wave function) quadrupole/magnetic dipole hyperfine structure

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr TTrraannssiittiioonnss

Polyatomic Molecules (continued). asymmetric tops: moments of inertia about all 3 axes differ. None of the projections of the total rotational angular momentum onto these axes is a good quantum number. Rotational levels are labeled by J where K- and K+ are K-K+ approximate quantum numbers.

Examples are: H O, SO , H S. 2 2 2

Transitions between different K-ladders are allowed.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TTrraacciinngg tthhee pphhyyssiiccaall ccoonnddiittiioonnss

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MM8822 iinn tthhee rraaddiioo,, mmmm,, ssuubbmmmm,, FFIIRR rraannggeess

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 SJL FFiinnee ssttrruuccttuurree lliinneess ooff aattoommss aanndd iioonnss

electrons: orbital angular momentum I, spin s atoms: Total orbital momentum L=l, Total spin S=s

Magnetic spin-orbit splitting leads to transitions in the 10-300m wavelength range.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFiinnee ssttrruuccttuurree lliinneess ooff aattoommss aanndd iioonnss electrons: orbital angular momentum I, spin s atoms: Total orbital momentum L=l, Total spin S=s

Magnetic spin-orbit splitting leads to transitions in the 10-300m wavelength range.

Spectroscopic notation: 2S+1 L J with the multiplicity 2S+1, the total orbital angular momentum L (denoted S, P, ...) total angular momentum J=L+S.

Fine structure doublet with S=1/2, L=1, J=3/2-1/2: C+ with a single fine structure transition 2P -2P at 158 m (1900GHz) 3/2 1/2 

Fine structure triplets with S=1, L=1: O with two transitions at 146 and 63 m : 3P – 3P - 3P  0 1 2 C with two transitions at 370 and 609 m (810 and 492GHz): 3P – 3P – 3P  2 1 0

Transitions are magnetic dipole transitions with J=0,+/-1, L=0, S=0. Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThhee [[NNIIII]] 112222 && 220055 mm lliinneess

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFIIRR

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFaarr iinnffrraarreedd eemmiissssiioonn

- Peak of the dust continuum emission of the cold dust

- Many of the strongest cooling lines lie in the FIR: [CII](158), [OI](63, 145), [NII](122, 205)

- highly excited rotational transitions of molecules like CO, HCN, HCO+, ... tracing hot star forming gas

- Light Hydrides: NH, NH , SH, PH, LiH, H2O, ... 2

- Important deuterated species: H D+, D H+ 2 2

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 AAttmmoosspphheerriicc ttrraannssmmiissssiioonn aatt TTHHzz wwaavveelleennggtthhss

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TTHHzz ttrraannssiittiioonnss

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMoolleeccuullaarr lliinneess aatt 880000--990000 GGHHzz

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFaarr iinnffrraarreedd eemmiissssiioonn

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFaarr iinnffrraarreedd eemmiissssiioonn

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 FFaarr iinnffrraarreedd eemmiissssiioonn

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 [[NNIIII]] 220055 aanndd [[CCIIII]] 115588 iinn tthhee MMiillkkyy WWaayy

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 [[NNIIII]] 220055 ffrroomm tthhee ggrroouunndd

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 [[CCIIII]] 115588mm ffrroomm ssppaaccee wwiitthh HHIIFFII//HHeerrsscchheell

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 3300mm oobbsseerrvvaattiioonnss ooff tthhee [[CCIIII]] lliinnee

= /(1+z)=1.9THz/(1+6.4)=256GHz  0

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 3300mm:: RReeddsshhiifftteedd [[NNIIII]] 220055mm ??

Walter, Weiss et al. 2009 7.6Jy/K at 1mm 0.17mK at 197GHz  =  /(1+z)=1.9THz/(1+6.4)=256GHz for [CII] 0 after 8h on-source  =  /(1+z)=1.46THz/(1+6.4)=197GHz for [NII]  0 time

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 RReeddsshhiifftteedd FFiinnee SSttrruuccttuurree LLiinneess

[CII] [NII]205 at z=6.4

Walter, Weiss et al. 2009

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 DDuusstt eemmiissssiioonn

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThheerrmmaall DDuusstt eemmiissssiioonn

S1.3 =1.3B  T d b S 2NH N H 11.1/T 1.3 = 2 −22 d −2 0.510 [mJy /11as beam] [cm ] exp 11.1/T d−1

A cloud with N(H )=1022cm-2 (A =10mag), T =10K: 2 v d S =20 mJy/beam (~3mK at 30m telescope, 7 Jy/K at 240GHz) 1.3 Sensitivity of MAMBO2/channel: ~30mJy in 1 sec

Multi-wavelength observations allow to derive T : d 3 S450 850 exp 17/ T d −1 =  S850 450 exp 32/ T d −1

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThheerrmmaall dduusstt eemmiissssiioonn

T = 8-15K, thermal dust emission peaks near 300 m d 

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThheerrmmaall DDuusstt eemmiissssiioonn

+ ISM dust grains have diameters of a ~ 0.01 to 1m + Efficient absorbers of short-wavelength radiation ( < a) + In equilibrium of heating and cooling, they emit a continuous spectrum closely resembling a thermal spectrum (T ) and smoothly varying absorption/emission d efficiency Q( )=Q ( / ).  0  0

Hacar et al. 2009 in prep.

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 TThheerrmmaall DDuusstt eemmiissssiioonn h = kT ---- 1.44 K = 30 GHz = 1 cm-1

Dust emission peaks at  = hc/((3+)kT) = 2.9/T mm

Example: Spectral Energy Distribution (SED) of a star forming galaxy. With T=50K, dust emission peaks near 60m in the far-infrared

MAMBO/30m

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMaappppiinngg tthhee ccoolldd dduusstt iinn MM5511

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 3300mm ++ 33..55mm

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 MMiilllliimmeetteerr wwaavvee RRaaddiioo TTeelleessccooppeess

+ Sensitivity: Large collecting surface area and good surface accuracy + Angular resolution: Large diameter of primary mirror + High altitude to reduce atmospheric amount of precipitable water vapor (pwv)

+ Heterodyne receivers for high spectral resolution >10-6 + Bolometer arrays for sensitive continuum mapping

IRAM 30m telescope 03:23:33.7 W 37:03:58.3 N

707m2 surface 420 Al panels on honeycomb backstructure 50 m surface accuracy 30m diameter 2850m altitude Pico Veleta/Sierra Nevada

230GHz/10kHz = 2.3 10-6 117channel 1.2mm Bolometer Camera

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 RRaaddiioo tteelleessccooppeess:: bbaassiicc ppaarraammeetteerrss

IRAM 30m telescope Beamsize (Resolution, Half power beam widths HPBW):

30” at 80GHz (Full moon has 30'=1800”) 10” at 230GHz 7” at 330GHz Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 RRaaddiioo tteelleessccooppeess:: bbaassiicc ppaarraammeetteerrss

IRAM 30m telescope

Aperture efficiency at 230GHz: 45%

Pointing accuracy: ~2”, i.e. 0.1 x HPBW(115GHz) or 0.3 x HPBW(345GHz) Surface accuracy: ~50m, i.e. /16 at 345GHz Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 IIRRAAMM 3300mm tteelleessccooppee:: ssiiggnnaall ppaatthh

2m secondary

30m primary

Alt-Azimuth mount: Azimuth Elevation

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 HHeerrsscchheell SSppaaccee OObbsseerrvvaattoorryy launched on 14.5.09

FIR/Submm Observatory: 30cm secondary 55-672 m

3.5m Telescope 12” beam at 158m (1.9THz, [CII])

~ 70% at 158 m A 

3.5m primary

see lecture by E.Caux

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009 EENNDD +some spare transparencies

Millimeter Astronomy – linked to the Far Infrared IRAM 30m Summerschool, September 2009