On Deuterated Polycyclic Aromatic Hydrocarbons in Space 杨雪娟 (XTU) Collabrators：李爱根 (MU), R. Glaser (MU) 星际物理与化学（昆明 2018）

Origin of Deuterium Spallation; Pregalactic Cosmic Rays; Shock Waves; Hot explosions; Disrupted NSs；× Big Bang Nucleosynthesis (BBN) √ Epstein+, 1976, Nature

of Cosmological Interests (D/H)prim  Cosmological parameters & Baryon–photon ratio  baryonic density of the Universe. The amount of deuterium in a galaxy  Cosmic nucleosynthesis & chemical evolution of the galaxy； Comparing the primordial and Galactic deuterium abundances  Discriminating among different Galactic chemical evolution models；

Primordial D abundance Measure using gas clouds that are seen in absorption against the light of an unrelated background light source (typically, a quasar) (Adams 1976). (D/H)prim ~ 25-28 ppm (Cooke et al. 2018; Zavarigin et al. 2018) Measure from the analysis of CMB observation data. (D/H)prim ~ 27 ppm (Cyburt et al. 2003; Coc et al. 2004; Dunkley et al. 2009)

Deuterium in the Local ISM ~83 − 92% of the primordial deuterium at the solar circle. Very close to the primordial value at low metallicity. Decreases towards higher metallicity, with very small scatter between D & O abundance. van der voort+, 2017

Deuterium in the Local ISM The D/H ratio measured from Copernicus, HST, IMAPS & FUSE shows large variations from sightline to sightline through the local ISM (Linsky et al. 2006; 2009). Linsky 2009

D Reduction: Astration Conversion of D into other elements by nuclear fusion in stars; Problems: Regions separated by only a few hundred pc have extremely different star formation histories;  No other evidence of such variations in star formation activity. Turbulent diffusion has not homogenized the elemental abundances in the gas;  Turbulent mixing is expected to be effective at mixing gas over length scales of hundreds of pc on 109 yr time scales.

Problem with Astration The expected associated variations of O/H is not observed. No anticorrelation of O-D abundance: Not astration; Other process! Draine 2006

Depletion of D: Role of Dust Carbonaceous grains & PAHs are a possible reposi- tory of missing D: Carbonaceous interstellar grains could incorporate enough deuterium atoms to substantially reduce the D abundance in the gas phase. Variations of (D/H)gas  Variations of D sequestered in dust grains from one sightline to another. Draine 2006

Kinetics of Deuteration Draine 2006 Doney+ 2016

DPAH: Spectral Features × 1.36 DPAH HPAH Hudgins (2004)

DPAH: Observations Orion Bar M17 Detection of deuterated-PAHs in Orion Bar & M17 PDRs. Peeters et al. (2004)

DPAH: Observations IRAS 12073-6233 NGC 3603 W17b Doney et al. (2016)

DPAH: Observations W51 M8 G75.783+0.343 Doney et al. (2016)

DPAH: Observations 6/41 Galactic HII regions show deuterated-PAH emission. Doney et al. (2016)

DPAH: Observations No evidence of large amount of deuterated PAHs Onaka et al. (2015)

DPAH: Our Work Modeling DPAH Emission (Draine & Li 2001; Draine & Li 2007 ) T=3500K, 6000K, 10000K, 22000K, MMP83 Goal: A database of DPAH spectra

A4.4/A3.3 : Calculated Molecules

A4.4/A3.3 : Calculated Molecules

D1-PAH Spectra C-D bending C-D stretch

D1-PAH Spectra C-D bending C-D stretch

Full Deuterated PAH Spectra C-D bending C-D stretch

D1-PAH Results: A4.4 & A3.3

D1-PAH Results: A4.4/A3.3

Summary Deuterium synthesis and depletion is of great importance and interests; Carbonaceous dust grains and PAHs could be a repository of the cosmic D, and a reason for different D/H abundance observed along different lines of sight; A systematic theoretical study of deuterated PAHs is urgent, and with our study one can get the D abundance easily from the observed C-D vibrational features. Thank you!