Looking for trees in the Looking for trees in the forestforest

LION, BM Seminar 5 June LION, BM Seminar 5 June 20082008

Ruth Buning Ruth Buning (LCVU, Amsterdam)(LCVU, Amsterdam)

Wim Ubachs Wim Ubachs (LCVU, Amsterdam)(LCVU, Amsterdam)

Michael Murphy Michael Murphy (Swinburne University, Melbourne)(Swinburne University, Melbourne) Lex Kaper Lex Kaper (UvA, Amsterdam)(UvA, Amsterdam)

Search for a variation of the proton-electron mass ratio on a cosmological timescale

Constants of natureConstants of nature

Why these numerical values?Why these numerical values? Really constant?Really constant?

(85) 61 672 1836.152

(96) 710 999 137.0351

e

p

m

m

Physical Review 82 (1951) 554

The proton-electron mass The proton-electron mass ratioratio

e

p

m

m

1

vibE

1rotE

ConstelecE

(Rigid rotor)

(Harmonic oscillator)

rotEvibrE

electrE

moleculeE

Molecular spectra, i.e. H2, NH3

Compare spectra over Compare spectra over ΔΔtt

– Astronomical data:Astronomical data: ΔΔt~Gyrt~Gyr

accuracy accuracy ~10~10-7-7

– Lab: Lab: ΔΔt~yr t~yr

accuracy accuracy →10→10-15-15

Empirical search for a Empirical search for a change in change in

QSO12 Gyr ago

Labtoday

90-112 nm ~275-350 nm

H2

Empirical search for a Empirical search for a change in change in

// and spectrum H and spectrum H22

Previous result, based on 76 lines in 2 Previous result, based on 76 lines in 2 QSO absorbers:QSO absorbers:

iabsi

i

i Kzz

1110

Accurately calculated

Lab: 5 x 10-9

QSO: (2-10) x 10-7

4σ

ii

i z10

absii

i zz 110

Decrease of 0.002% over the past 12 billion years PRL 96, 151101 (2006)

The QSO absorption The QSO absorption samplesample >2300 HI absorption systems>2300 HI absorption systems ~600 DLA’s~600 DLA’s 14 H14 H22 absorption systems absorption systems 6 useful6 useful 4 high-quality spectra4 high-quality spectra

Q0405: 37 lines at zQ0405: 37 lines at zabsabs=2.59=2.59

Q0347: 39 lines at zQ0347: 39 lines at zabsabs=3.02=3.02

Q2348: ~20 lines at zQ2348: ~20 lines at zabsabs=2.43=2.43 observed aug. observed aug. 07, VLT07, VLT

J2123: ~50 lines at zJ2123: ~50 lines at zabsabs=2.06 from Prochaska, Keck=2.06 from Prochaska, Keck

VLTVLT

Blue CCD chip Red CCD chip 1 Red CCD chip 2

Lyman- of quasar emissionzemis=3.0236

C IVemissionDLA at

zabs=2.615H2 regionzabs=2.426

DLA atzabs=2.93

DLA atzabs=2.426

QSO 1: Q2348 (VLT)

Wavelength (A)

H2 region

Resolution 103,000 ; zabs=2.0593

QSO 2: J2123 (Prochaska, Keck telescope)N

orm

aliz

ed fl

ux

H2

Ly

QSO 2: J2123

ResultsResults

QSO HQSO H22 spectra for spectra for // determination determination– Q0405: 39 linesQ0405: 39 lines– Q0347: 37 linesQ0347: 37 lines– Q2348: ~20 lines Q2348: ~20 lines – J2123: >50 linesJ2123: >50 lines

?

?

ConclusionsConclusions

2 2 → 4 objects→ 4 objects New result agrees on New result agrees on No consensus on systematicsNo consensus on systematics HD detection HD detection

Outlook: Observation J2123 with VLT Outlook: Observation J2123 with VLT next semesternext semester– 4 +16 hrs4 +16 hrs– Best object (bright, many HBest object (bright, many H22 lines, HD) for lines, HD) for

analysis analysis– Highest quality spectrumHighest quality spectrum

UVES: Ultraviolet – Visual Echelle Spectrograph

300-500 nm

420-1100 nm

slitviewslitview

CCD chipCCD chip

CCD chip: ThAr CCD chip: ThAr calibrationcalibration

Blue CCD chip Red CCD chip 1 Red CCD chip 2

Lyman- of quasar emissionzemis=3.0236

C IVemissionDLA at

zabs=2.615H2 regionzabs=2.426

DLA atzabs=2.93

DLA atzabs=2.426

QSO 1: Q2348 (VLT)

Wavelength (A)

Spectrum Q2348Spectrum Q2348DLA atzabs=2.615DLA at

zabs=2.426H2 region

Lyat zabs=2.615

Lyman limitat zabs=2.93

QSO 1: Q2348 (VLT)

L0R0 line of H2

> 7 velocity components

QSO 1: Q2348N

orm

aliz

ed fl

ux

Parameters describing 1 Parameters describing 1 absorption lineabsorption line

Voigt profileVoigt profile 3 free (‘cloud’) 3 free (‘cloud’)

parameters:parameters:– b,z,Nb,z,N

molecular data:molecular data:– lab wavelengthslab wavelengths– oscillator strengthsoscillator strengths– damping damping

coefficientscoefficients

b (km/s)

(1+z)rest

N (molecules

/cm2)

LCVU/Orsay, Meudon

Parameters describing Parameters describing multiple absorption linesmultiple absorption lines

From the same From the same ground state ground state (J=0, J=1, etc.)(J=0, J=1, etc.)

From different From different ground statesground states

Extra fit Extra fit parameter: parameter:

z

bbN

z

bb

N1 N2

z,

z,

SeeingSeeing

H Lyman seriesH Lyman series

Energy levels in a diatomic Energy levels in a diatomic moleculemolecule

Electronic Electronic

VibrationalVibrational vv

RotationalRotational JJ