Cosmic Rays: Gas Phase Astrophysics and Astrochemistry

Cosmic Rays:Cosmic Rays:Gas Phase Astrophysics and Gas Phase Astrophysics and

AstrochemistryAstrochemistry

Marco Spaans (Groningen)Marco Spaans (Groningen)

Rowin Meijerink (Leiden), Edo Loenen (Leiden), Rowin Meijerink (Leiden), Edo Loenen (Leiden), Paul van der Werf (Leiden), Padelis Papadopoulos (Bonn) Paul van der Werf (Leiden), Padelis Papadopoulos (Bonn)

CRDRs (CRs/SNe)CRDRs (CRs/SNe) MDRs (shocks)MDRs (shocks)

PDRs (UV/SBs)PDRs (UV/SBs) XDRs (X-ray/AGN)XDRs (X-ray/AGN)

Multi-Phase Medium; heating by CRs or

dust (Wolfire et al. 2003; Spaans & Norman 1997; Field et al. 1969)

Metallicity & Multi-Phase ISM:

Lower metallicity yields smaller molecular clouds

X-factor: CO/H2

Mihos et al. (1999), Bolatto et al. (1999), Roellig et al. (2006)

CR protons upto 100 CR protons upto 100 MeV listed: HMeV listed: H22 ionization, ionization,

while 1-20 GeV CRs while 1-20 GeV CRs responsible for bulk of responsible for bulk of ππ00

mesons mesons → 2→ 2γγ and, e.g., and, e.g., pp→pnpp→pnππ++

Effects of CRs?Effects of CRs? One often has a UV irradiated cloud edgeOne often has a UV irradiated cloud edge PDR model with CR rate = 5x10PDR model with CR rate = 5x10-15-15 s s-1-1; so SN ; so SN

rate for ~100 Mrate for ~100 M00/yr/yr Note small changes in C, OH and HNote small changes in C, OH and H22OO

CR ionization acts deep in CR ionization acts deep in molecular clouds (similar to XDRs)molecular clouds (similar to XDRs)

PDRs: 6 < E < 13.6 eVPDRs: 6 < E < 13.6 eV

Heating: Heating: Photo-electric emission from Photo-electric emission from grains and cosmic rays grains and cosmic rays

Cooling: Fine-structure lines like Cooling: Fine-structure lines like [OI] 63, 145; [CII] 158 μm [OI] 63, 145; [CII] 158 μm and emission by H and emission by H22, CO, H, CO, H22OO

10 eV photon penetrates 0.5 10 eV photon penetrates 0.5 magmag of dust of dust Heating efficiency ~ 0.1 – 1.0 %Heating efficiency ~ 0.1 – 1.0 %

XDRs: E > 1 keVXDRs: E > 1 keV

Heating: X-ray photo-ionization --> Heating: X-ray photo-ionization --> fast electrons - Coulomb heating fast electrons - Coulomb heating H and H H and H22vibvib

excitation - UVexcitation - UV Cooling: [FeII] 1.26, 1.64; [OI] 63; Cooling: [FeII] 1.26, 1.64; [OI] 63;

[CII] 158; [SiII] 35 μm; [CII] 158; [SiII] 35 μm; thermal H thermal H22vib; gas-dustvib; gas-dust

1 keV photon penetrates 101 keV photon penetrates 1022 22 cmcm-2 -2 of Nof NHH

Heating efficiency ~ 10 – 50 %Heating efficiency ~ 10 – 50 %

PDR (left) with n=10PDR (left) with n=1055 cm cm-3-3 and G=10 and G=103.53.5

XDR with n=10XDR with n=105 5 cmcm-3 -3 and Fand FX X = 5.1 erg s= 5.1 erg s-1 -1 cmcm-3-3

Note NNote NHH dependence H dependence H22, C, C++, C, CO, OH, etc., C, CO, OH, etc.

------------------------------------------------------- CR heating: ~8 eV per H2 ionization (H, He slightly different Cravens & Dalgarno 1978)

CRs can dominate gas heating for SFR > CRs can dominate gas heating for SFR > 100 Mo/yr; think of Arp220 and IMF 100 Mo/yr; think of Arp220 and IMF

through Mthrough MJeansJeans (Papadopoulos 2010)(Papadopoulos 2010)

CRs drive ionization and shift CCRs drive ionization and shift C++-C-CO -C-CO transitiontransition

CRs drive ionization, form molecular CRs drive ionization, form molecular ionsions

Particularly oxygen bearing ones!Particularly oxygen bearing ones!

BUTBUT: CRs : CRs ≠ X-≠ X-rays; only very rays; only very high CR rates high CR rates boost OHboost OH+ + and and HH22OO+ + (fine-(fine-

structure lines structure lines little affected by little affected by

CRs)CRs)

Mrk 231 Mrk 231 SPIRE data SPIRE data van der Werf et van der Werf et

al. (2010)al. (2010)

How about How about shocks?shocks?

M82, shock M82, shock tracer SiO 2-1 tracer SiO 2-1 + 4.8 GHz + 4.8 GHz radio radio (Garc(Garcíía-Burillo a-Burillo et al. 2001, et al. 2001, IRAM PdB)IRAM PdB)

M82, CO 6-5 (116K; Ward et al. 2003, CSO)M82, CO 6-5 (116K; Ward et al. 2003, CSO)

Jump ConditionsJump Conditions

J-Shocks of > 50 km/s lead to J-Shocks of > 50 km/s lead to high compression, molecule high compression, molecule dissociation and reformation dissociation and reformation

in the shock wakein the shock wake

J-shock structureJ-shock structure

J-shock chemistryJ-shock chemistry

SummarySummary

CRs (strongly) affect cloud chemistry (in CRs (strongly) affect cloud chemistry (in SBs) and can be distinguished from SBs) and can be distinguished from XDRs and shocks through OH, HXDRs and shocks through OH, H22O, OHO, OH++, , HH22OO++, H, H33OO+ + and high-J CO; not through and high-J CO; not through fine-structure and low-J CO lines if UV fine-structure and low-J CO lines if UV irradiation actsirradiation acts

For the future, ALMA will be crucial to For the future, ALMA will be crucial to provide spatial information on CR provide spatial information on CR exposed molecular cloudsexposed molecular clouds

Maloney et al. Maloney et al. (1996)(1996)

EnergeticsEnergetics

GG0 0 == 1.6x101.6x10-3-3 erg cm erg cm-2-2 s s-1-1

is the Habing flux over 6-13.6 is the Habing flux over 6-13.6 eVeV

Orion Bar has 10Orion Bar has 105 5 GG00

FFXX = = 84 L 84 L4444 r r22

-2-2 erg cmerg cm-2-2 s s-1-1 is the X-ray flux over 1-100 is the X-ray flux over 1-100 keVkeV with a with a

power law Epower law E-0.9-0.9 Think of Seyfert nucleus at 100 pc or Think of Seyfert nucleus at 100 pc or

TTauri star with 10 TTauri star with 103232 erg/s at 20 AU erg/s at 20 AU