1. 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

2. H2 in space 1970 IUE (1978-1996) Copernicus (1972-1981)
FUSE ( )

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

4. 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:

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

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

7. 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)

8. 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)
Bailly et al., Mol. Phys. 108 (2010) 827

9. 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

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

12. Empirical search for a change in =Mp/me

13. 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)

14. 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= (8)
GD133: Dm/m = (-2.7 +/- 4.7) x 10-5 z= (10)

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

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