[CII] 158 µm emission from L1630 in Orion B Cornelia Pabst Leiden Observatory November 29, 2017 in collaboration with: J. R. Goicoechea, D. Teyssier, O. Bern´e,B. B. Ochsendorf, M. G. Wolfire, R. D. Higgins, D. Riquelme, C. Risacher, J. Pety, F. LePetit, E. Roueff, E. Bron, A. G. G. M. Tielens Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 Introduction PhD student under supervision of Xander Tielens Leiden Observatory, Netherlands Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 1 / 30 [CII] 158 µm emission [CII] fine-structure line one of the brightest far-infrared cooling lines of the ISM, 1% of total FIR continuum ∼ [CII] line can be observed in distant galaxies correlation of SFR and [CII] intensity: [1] for 46 nearby galaxies, [2] on Galactic scale origin of [CII] emission: dense PDRs, cold HI gas, ionized gas, CO-dark gas on Galactic scale cf. GOT C+ [2] need to spatially resolve the ISM Orion molecular cloud as template region velocity-resolved mapping allows to form a 3D picture [1] Herrera-Camus et al. (2015) ApJ 800:1, [2] Pineda et al. (2014) A&A 570:A121 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 2 / 30 The optical window Image Credit: NASA/ESA/Hubble Heritage Team; M. Robberto/Hubble Space Telescope Orion Treasury Project Team Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 3 / 30 The infrared window Left: visible light. Right: infrared light (IRAS). Image Credit: Akira Fujii/NASA/IRAS Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 4 / 30 L1630 in the Orion B molecular cloud - visible Alnilam Flame Nebula (NGC 2024) Alnitak NGC 2023 σ Ori Horsehead Nebula IC 434 Image Credit: ESO, Digitized Sky Survey 2 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 5 / 30 L1630 in the Orion B molecular cloud - infrared Flame Nebula (NGC 2024) NGC 2023 σ Ori Horsehead Nebula IC 434 Image Credit: NASA/JPL-Caltech (WISE) blue: 3.4 µm, cyan: 4.6 µm, green: 12 µm, red: 22 µm. Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 6 / 30 L1630 in the Orion B molecular cloud L1630, comprising the iconic Horsehead Nebula, is illuminated/evaporated by the star system σ Ori at 3 pc distance (G0 = 100). edge-on geometry with respect to the illuminating source distance from us is 390 pc [3] an area of 120 170 was observed in [CII] using upGREAT onboard× SOFIA in December 2015 4.2 hours of Director's Discretionary Time beam size 15:900, spectral resolution 0:19 km s−1 [CII] line-integrated intensity of L1630 [3] Schaefer et al. (2016) ApJ 152:213 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 7 / 30 Knowledge vs. understanding Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 8 / 30 Comparison with other gas tracers 00 FIR 00 8 µm 00 CO (1-0) 00 00 00 0 0 9 0 2.0 15 15 15 50 50 50 8 3.0 ] 30 30 30 40 40 40 1 60 60 ] 60 ] − 1 40 30 1 40 30 40 30 sr 7 − − 80 80 80 1.5 2 sr sr 90 20 90 20 90 20 − 2 2 00 00 00 50 50 − 50 − 6 cm 30 30 30 0 0 0 1 cm cm 1.0 − 1 70 1 70 70 22 22 5 22 − − 60 60 60 1.0 erg s 7 erg s erg s 4 − 3 2 Dec (J2000) Dec (J2000) Dec (J2000) − − [10 50 20 50 20 3 50 20 40 40 [10 40 00 00 00 [10 0) 0.3 − m 00 00 00 0 0 0 10 10 µ 10 0.5 FIR 30 30 8 30 40 40 2 40 I I 30 30 30 20 20 CO (1 ◦ ◦ ◦ I 2 30 2 30 2 30 20 − − 1 − 30 0.1 30 0 30 0.0 4104000 4102000 5h4100000 4004000 4104000 4102000 5h4100000 4004000 4104000 4102000 5h4100000 4004000 RA (J2000) RA (J2000) RA (J2000) Far-infrared emission 8 µm emission traces CO emission traces (20-1000 µm) traces the UV field by fluo- the molecular gas the UV radiation field rescence of PAHs at deeper within the re-radiated by dust. the surface of a cloud. cloud [4]. [4] CO (1-0) data from Pety et al. (2017) A&A 599, A98 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 9 / 30 [CII] channel maps from 8 to 16 km/s, in steps of 0.5 km/s Tmb [K] 30 8.0 km/s 8.5 km/s 9.0 km/s 9.5 km/s 10.0 km/s 20 10 0 10.5 km/s 11.0 km/s 11.5 km/s 12.0 km/s 12.5 km/s 13.0 km/s 00 00 0 20 00 00 0 Dec (J2000) 30 ◦ 2 − 13.5 km/s 14.0 km/s 14.5 km/s 15.0 km/s 15.5 km/s 16.0 km/s 4103000 5h4100000 RA (J2000) Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 10 / 30 [CII] line-integrated intensity and structures 00 00 By means of the channel 0 100 15 maps and comparison with 90 other data, we identify sev- eral regions: 80 PDR1 CO clumps ] 1 70 − 00 Horsehead PDR 30 0 60 km s · PDR1 22 HII 50 [K PDR2 Horsehead v PDR 40 d PDR3 Dec (J2000) PDR2.5 mb 00 30 T 00 R PDR2.5 0 PDR3 30 ◦ 20 CO clumps 2 PDR2 − CO-dark cloud CO-dark cloud 10 HII region 0 4104000 4102000 5h4100000 4004000 RA (J2000) Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 11 / 30 Spectra towards molecular cloud 20 Horsehead PDR2 south 20 10 10 0 0 PDR1 PDR3 20 15 [K] 10 10 mb 5 T 0 0 20 PDR2 CO-dark cloud 10 10 5 0 0 0 5 10 15 20 0 5 10 15 20 25 v [km/s] line widths < 5 km=s Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 12 / 30 Spectra towards HII region 1.5 HII region north HII region south 1.0 1.0 [K] 0.5 mb 0.5 T 0.0 0.0 0 5 10 15 20 0 5 10 15 20 25 v [km/s] [CII] line is fainter and broader: 9 km=s (left) and 5 km=s (right) ∼ ∼ Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 13 / 30 Line cut through the molecular cloud 00 00 0 9 PAH 8 µm 15 8 Hα ] 7 1 100 − sr [CII] 2 6 − 00 30 cm 0 CO 5 1 22 − PACS 160 µm 4 erg s 3 Dec (J2000) − 3 [10 80 00 m µ 00 0 8 2 I 30 ◦ 2 − 1 0 4104000 4102000 5h4100000 4004000 . RA (J2000) u 60 . a IRAC 8 µm image 40 20 0 1.0 0.8 0.6 0.4 0.2 0.0 offset [pc] PDR3" PDR2.5" PDR2" Horsehead" PDR We recognize the prototypical layered structure of a PDR. Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 14 / 30 Correlation plot I[CII] vs. I8 µm ] 1 − sr 2 3 10 4 − − · cm 1 − [erg s CO-dark cloud CO clumps [CII] I Horsehead neck 4 1 10− · Horsehead PDR PDR1 PDR2 PDR3 3 3 2 1 10− 3 10− 1 10− · · 1 2 1 · I8 µm [erg s− cm− sr− ] [CII] emission is well-correlated with PAH emission. Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 15 / 30 Correlation plot I[CII] vs. IFIR ] 1 − sr 2 3 10 4 − − · cm 1 − [erg s CO-dark cloud CO clumps [CII] I Horsehead neck 4 1 10− · Horsehead PDR PDR1 PDR2 PDR3 3 2 2 1 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ] Correlation of [CII] with FIR emission is not as good as with PAH emission. Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 16 / 30 Correlation plot I[CII]=IFIR vs. IFIR CO-dark cloud 2 3 10− CO clumps · Horsehead neck Horsehead PDR PDR1 PDR2 PDR3 FIR /I 2 1 10− [CII] I · 3 10 3 − 3 2 2 1 · 3 10− 1 10− 3 10− 1 10− · · 1 · 2 1 · IFIR [erg s− cm− sr− ] [CII] cooling efficiency I[CII]=IFIR varies by a factor of 10 within the mapped area. Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 17 / 30 Modelling the correlation plots We built edge-on models based on [5] with FUV intensity G0 = 100 appropriate for σ Ori, AV;los and n determined from the data. We determined the line-of-sight depth of the cloud AV;los from the dust optical depth τ160, i.e FIR continuum photometry. We find AV;los 5:0 mag in PDR1, AV;los 2:5 mag in PDR2, and ' ' AV;los 0:5 mag in the Horsehead PDR ' We determined the gas density n from the scale length of the line + cuts, assuming AV = 2 for the transition C /C/CO. We find n 3 103 cm−3 in PDR 1 and 2, n 4 104 cm−3 in the Horsehead' PDR· ' · [5] Tielens&Hollenbach (1985), Wolfire et al. (2010), Hollenbach et al. (2012) Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 18 / 30 3 3 Model result for n = 3 10 cm− on physical scale · 3 2 n = 3.0 10 cm− 140 · 100 T K 60 20 1 10− AV,los = 2.5 AV,los = 5.0 2 10− 3 10− IFIR 4 1 10− I[CII] − sr 5 I /I 2 FIR 10− [CII] − ICO (1 0) cm 6 − 1 10− − 7 10− erg s 8 10− 9 10− 10 10− 10 11 − 2.0 1.5 1.0 0.5 0.0 x [pc] In a nutshell: Luke-warm surface layers, T 120 K, emitting in [CII] and FIR ' + Colder gas mainly emits in CO, transition C /C/CO at AV 2 ' Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 19 / 30 Correlation plot I[CII] vs.