How to Measure Evolution in the Fundamental Constants of Physics

with Large Telescopes

Chris Churchill(Penn State)

…and sneak in astronomical observations on the evolution of galaxies and the intergalactic medium

Executive Summary

1. Motivations2. CMB/BBN 3. And the Winner is…QALs4. Fine Structure Constant5. Electron-Proton Mass6. Bread and Butter Astronomy7. Concluding Remarks

Classes of Theories

Attempts to solve some cosmological problems…

• Multi-dimensional and String Theories

• Scalar Theories (varying electron charge)

• Varying Speed of Light Theories

Unification of quantum gravity with other forces…

Couples E+M to cosmological mass density…Modified Bekenstein theories…

Fundamental “Constants” that are ripe for investigation…

1. = e2/hc

2. x = 2gp/

3. y = 2gp

4. = mp/me

zo1

xxzopt – z21)/(1+z

yyzmol – z21)/(1+z

zi = zo + bKi b = (1 + zo)

Last scattering vs. z CMB spectrum vs. l

CMB Behavior and ConstraintsSmaller delays epoch of last scattering and results in first peak at larger scales (smaller l) and suppressed second peak due to larger baryon to photon density ratio.

Solid (=0); Dashed (=-0.05); dotted (=+0.05)

(Battye etal 2000)

BBN Behavior and Constraints

D, 3He, 4He, 7Li abundances depend upon baryon fraction, b.

Changing changes b by changing p-n mass difference and Coulomb barrier.

Avelino etal claim no statistical significance for a changed from neither the CMB nor BBN data.

They refute the “cosmic concordance” results of Battye etal, who claim that =-0.05 is favored by CMB data.

(Avelino etal 2001)

QSO absorption line methods can sample huge time span

QSO Absorption Lines (history)

Savedoff (1965) used doublet separations of emission lines from galaxies to search for evolution (first cosmological setting)

Bahcall, Sargent & Schmidt (1967) used alkali-doublet (AD) separations seen in absorption in QSO spectra.

z = 0 + q1x + q2yz = redshifted wave number

x = (z/0)2 - 1 y = (z/0)4 - 1

0 = rest-frame wave number

q1, q2 = relativistic correction coefficients for Z and e- configuration

Mg II 2803Mg II 2796Fe II 2600Fe II 2586Fe II 2382Fe II 2374Fe II 2344

The Many-Multiplet Method

SIMULATIONS….

HIRES/Keck resolution and pixel sampling rate, infinite signal to noise

Black lines are unshifted data.

Red lines are shifted for +10-4.

Fe II shifts to blue by ~10(1+ times that of Mg II, though each Fe II has a unique shift magnitude.

Cr II shifts to red compared to Si II and Zn II shifts blue as compared to Si II, also with different shift magnitudes

Relative Shifts of Large Shifters for =+10-4

Webb et al Results

1. 49 absorption cloud systems over redshifts 0.5–3.5 toward 28 QSOs compared to lab wavelengths for many transitions

2. 2 different data sets; low-z (Mg II, Mg I, Fe II) high-z (Si II, Cr II, Zn II, Ni II, Al II, Al III)

3. Find = (–0.72±0.18) × 10-5 (4.1) (statistical)

4. Most important systematic errors are atmospheric dispersion (differential stretching of spectra) and isotopic abundance evolution (Mg & Si; slight shifting in transition wavelengths)

5. Correction for systematic errors yields stronger evolution

= (–0.72±0.18) × 10-5 (4.1) (statistical)

(Webb etal 2001)

Soon to the PressPreliminary Findings…

Now have a grand total of 138 systems due to adding the HIRES data of Sargent et al.

Find = (–0.65±0.11) × 10-5 (6) (statistical)

The Future

Same and new systems observed with different instruments and reduced/analyzed by different software and people.

Build UVES/VLT and HRS/HET data base in order to reproduce the HIRES/Keck results

Raid STIS/HST archive (already done) to perform the study at z=0 (in Galactic HVCs).

(Murphy etal 2001)

Measuring y=gp2 and y=gp2 Evolution is ProblematicThe line of sight probed by 21-cm may not be the same probed by the QSO!

Carilli etal (2001) attempt to minimize this using VLBI for 21 cm.

(Potekhin etal 1998)

Measuring =mp/me is a simple matter of finding damped Ly-alpha systems with hydrogen molecules!

Not so easy, only five known to date.

Combining 2 QSOs, Ivanchik etal (2002) find

= (5.7 +/- 3.8) x 10-5

At z=3.

Searching with Sara Ellison (ESO) and Max Pettini (IoA) using CORALS

(Potekhin etal 1998)

Vibrational and Rotational states of H2 have different dependence! This is parameterized using sensitivity coefficients, K.

Ki = dln(i)/dln(

Simple linear regression

zi = zo + bKi

b = (1 + zo)

Though Potekhin etal (1998) and Ivanchik etal (2002) have placed excellent limits on , a zero redshift calibration would be useful to check that the sensitivity coefficients are not systematically influencing the results.

(Martini etal 2000)

The photodissociation regions of Galactic reflection nebulae show strong H2 emissions lines. These emission lines can be used to place z=0 constraints on .

This has never been tried, but is in principle straight forward and favorable in that reflection nebulae are abundant (good stats).

The phoenix on Gemini-S is ideally suited for this… R=50,000 and a signal to noise of 30/pixel on a K=12 object in 1 hour (in the continuum)!!

Cooling Flow Galaxies exhibit strong H2 emission lines!

Seven CF galaxies known to date with H2 emission. Redshifts are in the range 0.05 to 0.15.

Kinematics of gas (~500 km/s) may be a problem, but experience with all gas is that the lower the ionization level, the smaller the physical size and the narrower the profiles.

Thus, it is expected that these features will break up into multiple narrow velocity components.

Exploring this with Alexander Delgarno (CfA)

(Falcke etal 1998)

And now for something completely different…

A uniform and high quality library of QSO Spectra can be fully exploited to learn many fundamental properties of the high redshift universe.

• Kinematic, chemical, and ionization conditions of galactic gas and of the Lyman alpha forest.

• Evolution in number per unit redshift (number density X cross section)

• Detailed photo-ionization modeling yields chemical evolution and size constraints

• Directly probe inter-galactic and galactic conditions to highest redshifts

Mg II absorbers are ideal - associated with galaxies and with Lyman alpha forest clouds… charts first generation of stars in all environments…

We require high resolution spectra…

(Churchill 1997)

(Churchill etal 2001)

(Churchill et al 1999; Rigby etal 2002)

Predicted for a decade to not exist… these spectra were peppered with “weak” systems….

Summary of Weak Mg II Systems

(Churchill & Vogt 2001)

The kinematics of the “Strong” Systems

Establishing Direct Connection with Galaxies

• Note weak systems are not identified with galaxies

• Strong systems typically within 40 kpc of QSO line of sight

A pilot project in which the stellar rotation curves of five z=1 edge-on spiral galaxies were measured with LRIS/Keck revealed that the absorption traces the disk kinematics far out into the halo (Steidel etal 2002).

We are currently extending this project to 30 galaxies with HST imaging, high resolution absorption line data, and stellar rotation curves (spirals) or velocity dispersions (ellipticals).

(Churchill 2001)

Interpreting Complex Absorption Line Profiles

Each absorption line arises from an individual cloud with some line-of-sight velocity.

Complex profiles are blends of many clouds that are distributed in some geometric/kinematic arrangement(s) in and/or near normal bright galaxies.

Simple models of galactic disk geometry and kinematics and of “halo” geometry and kinematics are statistically consistent with the observed complex profiles.

(Charlton & Churchill 1996, 1998; Churchill & Vogt 2001)

State of the Mg II Union

(Churchill & Charlton 2002)

HRS (z = 0.6-2.2) and JCAM (z = 2.2-3.8) on HET

(Churchill & Charlton 2002)

Simulated JCAM/HET Spectrum

JCAM/HET Commissioning Data

R=11,000~ 28 km/s

J=12=2500 sec

~1.15 m

The Future1. Continue work in collaboration with UVES/VLT and bring

in HRS/HET. Long term (10 years)- independent work at R=120,000 with HRS!

2. Independently measure in Galactic HVCs using STIS/HST archival data

3. Measure in Galactic reflection nebulae (need pilot) and eventually in cooling flow galaxies to z=0.2. This is H2 emission line work. Search for high-z DLAs with H2 molecules and measure in absorption to z=3-4.

4. Extend studies of Mg II kinematics, chemical, and ionization conditions to z~4 with UVES/HRS/JCAM

5. Continue establishing kinematic connections with Mg II absorption and stellar kinematics; establish nature of “weak” systems.

Varying Electron Charge Theories

Variation occurs over matter dominated epoch of the universe.

(Barrow etal 2001)

Varying Speed of Light Theories

Motivation is to solve the “flatness” and “horizon” problems of cosmology generated by inflation theory (Barrow 1999; Moffat 2001).

Theory allows variation in to be ~10-5H0 at redshift z=1. Evolution is proportional to ratio of radiation to matter density.