H3+, the new probe for ionization rate

Takeshi Oka

Department of Astronomy and Astrophysics and Department of Chemistry

The Enrico Fermi Institute, University of Chicago

Cosmic Ray Interactions: Bridging High and Low Energy AstrophysicsLeiden, March 14, 2011

Tom Geballe Gemini Observatory

Nick Indriolo, Ben McCall University of Illinois, Urbana-Champaign

the cosmic ray

7

Astronomers’ Periodic Table

Ben McCall

HHe

C N O Ne

Si S ArMg

Fe

6

Hydrogenic Probes

H2+

H

H H2

H+ H3+

H H2

+

H3+

Ewen & Purcell 1951Muller & Oort 1951

Carruthers 1970Spitzer et al. 1973 Geballe & Oka 1996

~ 10-7 10-8

92

quadrupole

dipole 10

aI

I

5

H3+ the most direct probe for soft cosmic ray

4

H3+ the most direct probe for soft cosmic ray

Simple chemistry: production

H2 → H2+ + e

= 10-18 ~ 10-14 s-1

dn(H3+)/dt = dn(H2

+)/dt = n(H2)

H2+

H H2

H+ H3+

H2+ + H2 → H + H3

+

R = kLn(H2)

10-9 cm3 s-1 104 - 102 cm-3

1.7 eV

P. Langevin 1905 r-4

OH, HD

3

H3+ the most direct probe for soft cosmic ray

Simple chemistry: destruction

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

104

105

106

n(X

)

10-1

100

101

102

103

104

105

106

n(H)

Dense Clouds Diffuse Clouds

H2

HCO

C+H3

+

Dense Clouds (~104 cm-3) C CO

H3+ + CO → H2 + HCO+ dn(H3

+)/dt = kLn(H3+)n(CO)

Diffuse Clouds (~102 cm-3) C C+ + e

H3+ + e → 3H, H2 + H dn(H3

+)/dt = ken(H3+)n(e)

Lk

ek

n(H3+) =

n(H3+) =

=

10-9 cm3 s-1 r-4

10-7 cm3 s-1 r-1

)CO(

)H( 2

n

n

)C(

)H( 2n

n

Steady state = n(H2)

(nH/nC)f(H2)/2N(H3+)/L

f(H2) = 2n(H2)/nH

2

H3+ the most direct probe for soft cosmic ray

L N(H3+)

L = 2 ke N(H3+) (nC/nH)SV RC/H / f(H2)

L = 2 ke N(H3+) (nC/nH) / f(H2)

L = 2 kL N(H3+) (nC/nH)1.5

Dense clouds

Diffuse clouds

Galactic center

L = (0.6 – 2.3) 102 cm s-1

N(H3+)obs = (1.1 – 5.2) 1014 cm-2

N(H3+)obs = (0.21 – 2.4) 1014 cm-2

N(H3+)obs = (1.8 – 6.1) 1015 cm-2

L = (0.4 – 4.4) 104 cm s-1

L > (1.2 – 4.2) 105 cm s-1

Goto, Usuda, Nagata, Geballe, McCall, Indriolo, Suto, Henning, Morong, Oka, 2008, ApJ, 688, 306

Indriolo, Geballe, Oka, McCall, 2007, ApJ, 671,1736

1

= 3 10-17 s-1 L = (0.6 – 2.3) pc

= 1.5 10-15 s-1 L > (24 – 84) pc

= 4.5 10-16 s-1 L = (3 – 29) pc

RC/H 3 – 6.7

McCall, Geballe, Hinkle, Oka, 1999, ApJ, 522, 338

Rolleston et al. 2000, A&A, 363, 557Esteban et al. 2005, ApJ, 618, L95

RX 3 – 10, > 3Sodroski, et al. 1995, ApJ 452, 262Arima, Sofue, Tsujimoto, 1996, PASJ 48, 275

Telescopes and spectrometersTelescope D Spectrom. λ/Δλ UKIRT 3.8 m CGS4 40,000 Mauna Kea 1982 Subaru 　 8.2 m IRCS 20,000 Mauna Kea 2000Gemini South 8 m Phoenix 60,000 Cerro Pachon 2003VLT 8.2 m CRIRES 100,000 Cerro Paranal 2006 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011

Subaru UKIRTGemini South

VLT

Gemini North

Remarkable similarity between velocity profilesof H3

+ toward Iota and H2O+, CH+ toward Sgr B2 Herschel observations of ortho- and para-oxidaniumyl (H2O+) in spiral arm clouds toward Sgr B2(M) ⋆

P. Schilke,1,2 C. Comito,2 H. S. P. M¨uller,1 E. A. Bergin,3 E. Herbst,14 D. C. Lis,4 D. A. Neufeld,20 T. G. Phillips,4 T. A. Bell,4 G.A. Blake5 E. Caux,6,7 C. Ceccarelli,8 J. Cernicharo,9 N. R. Crockett,3 F. Daniel,9,10 M.-L. Dubernet,11,12 M. Emprechtinger,4 P. Encrenaz,10 M. Gerin,10 T. F. Giesen,1 J. R. Goicoechea,9 P. F. Goldsmith,13 H. Gupta,13 C. Joblin,6,7 D. Johnstone,15 W. D. Langer13 W. B. Latter16 S. D. Lord,16 S. Maret,8 P. G. Martin,17 G. J. Melnick,18 K. M. Menten,2 P. Morris,16 J. A. Murphy,19 V. Ossenkopf,12,21 J. C. Pearson,13 M. P´erault,10 R. Plume,22 S.-L. Qin,13 S. Schlemmer,1 J. Stutzki,1 N. Trappe,19 F. F. S. van der Tak,21 C. Vastel,6,7 S. Wang,3 H. W. Yorke,13 S. Yu,13 N.Erickson,25 F.W. Maiwald,13 J. Kooi,4 A. Karpov,4 J. Zmuidzinas,4 A. Boogert,4 R. Schieder,1 and P. Zaal21A&A June 22 2010

Geballe & Oka, 2010, ApJ, 709, L70

H3+ R(1,1)l

H2O+ 111← 000

H2O+ 110← 101

17 pc

3 kpc ScutumSgittarius

E. Falgarone et al. 2010

0