Photodissociation in Astrochemistry Leiden, 5 Feb. 2015 Molecular hydrogen in the photosphere of White Dwarfs Wim Ubachs VU University Amsterdam Photodissociation in Astrochemistry Leiden, 5 Feb. 2015

H2 in space 1970 IUE (1978-1996) Copernicus (1972-1981) FUSE (1999-2007)

Earth-based observations of H2; in high redshift quasar sightlines Keck VLT Spectrum of J2123—001 at z = 2.05

Q1441+272 ; the most distant H2 absorber zabs = 4.22 ; 1.5 Gyrs after the Big Bang on ground March 2013 Bagdonaite et al. Phys. Rev. Lett. Feb 2015 Arxiv:1501.05533

Cosmic Origins Spectrograph on HST (R ~ 20,000) Astroph. J. Lett. 766, L18 (2013) Cosmic Origins Spectrograph on HST (R ~ 20,000)

Contributions of many lines in the B-X Lyman system T=13,000 K

H2 laboratory wavelengths XUV-laser excitation (1 + 1’ REMPI detection) P(3) C-X (1,0) R(0) B-X (9,0) line Ubachs, Phys. Rev. Lett. (2004) Reinhold et al, Phys. Rev. Lett. (2006) For HD Ivanov et al., Phys. Rev. Lett. (2008)

H2 laboratory wavelengths Lyman bands Two-photon laser Doppler-free Two-step excitation FT-IR+Vis XUV 2-photon deep-UV EF 1Sg+ B 1Su+ X 1Sg+ 1s2s FTIR and FT-VIS 1s2 Dl/l ~ (5 – 50) x 10-9 Salumbides et al. Phys. Rev. Lett. 101 (2008) 223001 Bailly et al., Mol. Phys. 108 (2010) 827

Determination of accurate wavelengths for Lyman bands Experimental level energies Bailly et al. Mol. Phys. (2010) B-state: Limited to J<13 X-state: accurate calculations by Pachucki & Komasa et al. Higher J (J>12): ab initio framework Abgrall/Roueff

Data base for hot H2 > 1500 lines included to model the spectrum

Empirical search for a change in =Mp/me

Varying Constants ? Coupling constants are free parameters in Standard Model Bekenstein-Barrow –Sandvik – Mageijo – Light scalar fields f Jacob Bekenstein 1) Coupling to cosmology Variation on cosmological time scales 2) Coupling to matter density -> “chameleons” Coupling to gravity (test EEP)

Dependence of Dm/m on gravitational field Insert fit parameters: T and Dm/m and z Pv”,J” and Ki included GD29-38: Dm/m = (-5.9 +/-3.8) x 10-5 z=0.0001360 (8) GD133: Dm/m = (-2.7 +/- 4.7) x 10-5 z=0.0001820 (10)

SF6/Cs measurement [5] Chardonnet, PRL 100, 150801 (2008)

Thanks & Acknowledgement Michael Murphy Julija Bagdonaite Edcel Salumbides Simon Preval Martin Barstow John Barrow J. Bagdonaite, et al. Phys. Rev. Lett. 113, 123002 (2014) E.J. Salumbides et al. ArXiv 1412.6920 Evelyne Roueff Herve Abgrall