The Strange UniverseThe Strange Universe

Sanjay K. GhoshDepartment of Physics

Bose InstituteKolkata

Early EffortsEarliest astronomical records : 2000 - 1500 BC

Mesopotamian priests : systematic astronomical records Sumarians, Babylonians, and Egyptians develop astronomy

Greece School : 600BC - 200AD Anaximander, Pythagores, Aristotle, Hipparchus, Ptolmey Earth is the center of Universe

Indian Contribution : 500 – 600 AD

Aryabhatta: Sun is the centre of the Solar System. Varahamihira : earth attract bodies.

Arab School : 850 - 1200AD Al-Battani, Al-Sufi, Al-Biruni, Arzachel

Andromeda Galaxy, idea of elliptical orbits for planets, Appearance of Milky way

Modern Astronomy 1543ADPolish priest, Nicholas Copernicus: Sun centered solar system (Revival of the idea of Aristarchus of Samos 200BC) 1572ADDanish Astronomer,Tycho Brahe – Last naked-eye astronomer :exploding star- NOVA, Comet orbit

Spectacle maker Hans Lippershey (1570 -1619): Assembled first telescope

1610ADItalian, Galileo Galilei : Use of telescope1620AD John Kepler : Kepler’s Law

More and better observational data

Distance measurement known from 1700

Works only for nearby star

Need for Standard Candles to measure larger distances

Standard Candles : Cepheid Variables

giant yellow star pulsing regularly by expanding and contracting

fairly tight correlation between period of variability and absolute stellar luminosity (total light per sec)

Luminosity related to apparent brightness (light received/area/sec.) and distance (from parallax method)

Period – Luminosity Law

(Henrietta Swan Leavittin 1912)

A photograph such as this shows bright stars as larger disks than fainter stars

Harvard College Observatory

Edward Charles Pickering Director of HCO (1877-1919)

"Pickering's Harem" or, Harvard Computers.

The synthesis of helium At temperatures above 1010 K, any deuteron formed from a neutron—proton collision was quickly disrupted by a collision because the thermal energies involved often exceeded the 2.2 MeV binding energy of the deuteron. The only nuclei existing at these temperatures were single protons and neutrons.

In normal circumstances a neutron beta decays with a mean life of about 15 minutes to a proton, an electron and an anti-neutrino,

At high temperature and density, neutrons can be transformed to protons, and protons can be transformed to neutrons in collisions involving thermal neutrinos, anti-neutrinos,electrons & positrons

Heavier neutron – more energy needed for creation –

no. of neutron < no.of proton

proton &neutron

of difference massMeV3.1 m

n and p ratio decreased with decreasing T – expanding Universe

Ratio became about 1/5 just below 1010 K – further decrease due neutron decay

After a few minutes, when n decay had reduced the n-p ratio to about 1/7, the universe was cool enough for a sequence of two-body reactions - bound states of n and p. At about 109 K deuteron nuclei began to be present in significant amounts as n-p radiative capture, n + p d + , competed successfully with deuteron photodisintegration, + d n + p. Capture of neutrons and protons by deuterons led to the formation of tritons and helium-3.

These nuclei in turn captured p and n to form helium-4. Since helium-4 is by far the most stable nucleus in this region of the periodic table, nearly all the neutrons that existed when the temperature was 109 K were converted into helium-4. Moreover, the absence of stable nuclei with mass 5 and 8 prevented the formation of more massive nuclei, apart from small amounts of lithium-7.

• Problem with BBN • Input for BBN – baryon to photon ratio• 5.89 x 10-10 < η < 6.39 x 10-10 baryons/photon

• BBN provided the raw material for the first stars

• Gravitational Contraction

Gravity is the driving force behind stellar evolution. Most importantly it leads

to the compression of matter and thence to the formation of stars. It leads to the conditions where nuclear forces play a constructive role in thermonuclear fusion. The transformation of hydrogen to helium in the hot compressed centres of stars is often followed by a further compression and the transformation of helium into more massive elements such as carbon, oxygen and iron, the star dust out of which we are all made.

Burning Chain H He C O Ne Si Fe

Process Fuel Product Temperature (K)

Minimum Mass M

H Burning H He 10-30 X 106 0.1

He Burning He C, O 2 X 108 1

C Burning C O, Ne, Na, Mg

8 X 108 1.4

Ne Burning Ne O, Mg 1.5 X 109 5

O Burning O Si, S, Kr, Ca 2 X 109 10

Si Burning Si Fe 3 X 109 20

Arthur Eddington (1924) : Mass-Luminosity relationship

Outward radiation pressure = inward gravity

Fritz Zwicky (1933) :

Measured velocity of eight galaxies in COMA cluster

Mass/Luminosity is much larger than expected from mass-luminosity relation

Vera Rubin (1975) most stars in spiral galaxy orbit roughly at the same speed

Presence of DARK MATTER in the galaxies

The average speed of galaxies within a cluster depends on the total mass of the cluster, since each galaxy is attracted by the gravity of all the others.

From the observed speeds of galaxies moving within the Coma cluster, Zwicky calculated its total mass. -added up all the light from the galaxies in the cluster and used it to calculate the mass in the form of luminous stars. - mass of the cluster based on the speed of its galaxies was about ten times more than the mass of the cluster based on its total light output. - Coma cluster must contain an enormous quantity of unseen matter, with enough gravity to keep the rapidly moving galaxies from flying apart

- Dark Matter

r

GMv

22

• Gravitational lensing : one or more images of a distant source

Gravitational Microlensing

Darkmatter: What are they

• DEAD stars ????

• Primordial black holes ???

• Weakly Interacting massive particles???

Hubble’s Law (1929) : Expanding Universe

- Cepheid variables – Leavittin’s relation

• Recessional Velocity = Hubble's constant times distance

• V = Ho D where

• V is the observed velocity of the galaxy away from us, usually in km/sec

• H is Hubble's "constant", in km/sec/Mpc

• D is the distance to the galaxy in Mpc

V is related to red shift

Doppler Effect

Doppler Effect

Gravitational Red Shift:

A heavy object is denoted by a deformation of space represented by the funnel. As light leaves the vicinity of this object it is shifted towards the red: for a sufficiently compact and massive object a blue laser on the surface will be seen as red in outer space.  

Comological red shift

Going the distance

Although Cepheid variable stars have proved extremely valuable as standard candles in astronomy for many years, they are not bright enough to be used at high redshifts. However, astronomers have found a very special type of supernova to take their place.

The light emitted by stars and gas in distant galaxies has been stretched to longer wavelengths during its journey to Earth. This shift in wavelength is given by the redshift, z = (λobs – λ0)/λ0, where λobs is the wavelength we see on Earth and λ0 is the wavelength of the emitted light.

Prime methods for measuring extragalactic distances - “standard candles” such as Cepheid variable stars.

The distance to a Cepheid - first measure its period to obtain the luminosity

-then compare this with the observed intensity to calculate the distance.

-Thus, redshifts and distances to objects moving in the “Hubble flow” (the region beyond the gravitational influence of our local group of galaxies) have been charted, revealing the Hubble law: d = (cz/H0), where c is the speed of light and H0 = 72 ± 8 km s-1 per megaparsec (Mpc) is the Hubble constant (1 Mpc is equal to 3.26 million light-years).

Can one explore farther : New Candles

Type IA supernova

Binary system of white dwarf and red giant

accretion onto the white dwarf

reaches Chandrasekhar Limit

Gigantic thermonuclear reaction

Mid 1990

High z Supernova search

(Mt. Stromlo and Siding spring

Observatory,Australia)

International Supernova Cosmology

Project (LABL, USA)

1998 - Recorded 100 or so supernova

Observations of supernovae can be used to chart the history of the cosmic expansion. (a) The distance to a type 1a supernova is obtained from its luminosity, which is calibrated by its light curve and spectrum, and its observed intensity.

(b) Meanwhile, the expansion of the universe shifts features in the supernova spectrum to longer wavelengths by a factor characterized by the redshift.

(c) By plotting distance versus redshift for a large number of supernovae, we can chart how the universe has expanded over time.

orange circles -data points along with the theoretical prediction:

a universe with 30% matter and 70% cosmological constant (blue).

universe with 30% matter and spatial curvature (red dashed)

100% matter (purple dashed).

Green- no acceleration or deceleration

(Rainer Sachs & Art Wolfe)

Integrated Sachs-Wolfe (ISW) Effect:Integrated Sachs-Wolfe (ISW) Effect:Gravitational potential wells of dense and overdense

regions in the universe have been stretched and made shallower over time

Influence of repulsive gravity (or acceleration)

• The Sloan Digital Sky Survey (SDSS) identifies Galaxy Concentrations and determines their positions on the sky.

• The Wilkinson Microwave Anisotropy Probe (WMAP) measures the angular pattern of energies of the Cosmic Microwave Background Radiation (CMBR) [reds,yellows, greens, blues, purples, in order of increasing energy].

Position of the peak in this spectrum depends on the geometry of the universe. Recent observations confirm that the peak occurs at the position predicted for a flat universe (blue). In an open universe the peak would be to the left (red), and in a closed universe it would be on the right (green).

Expansion of the Universe is Expansion of the Universe is acceleratingaccelerating

Evidence of Dark Energy

• WMAP• (Wilkinson Microwave

Anisotropy Probe)

• Universe is 13.7 billion years old (±1%) • First stars ignited 200 million years after

the Big Bang

• Content of the Universe: 4% Atoms, 23% Cold Dark Matter, 73% Dark Energy

• Expansion rate (Hubble constant): H0= 71 km/sec/Mpc (±5%)

Evolution of the conceptEinstein : Cosmological Constant

General theory of relativity (1916)

Universe either expands or contracts

For Static Universe

Cosmological Constant

Hubble’s Theory (1929) Expanding Universe

Cosmological Constant dropped

Attempts for revival 1960 : Vacuum energy of particles and

fields should generate 1980 : Theory of Inflation

Early Universe goes through brief period of accelerated exponential expansion

-ve pressure drives the expansion

Inflaton

Candidates : ( pDark = w eDark )

Cosmological Constant : Static (w = -1)

Quintessence : Dynamic (w > -1)

Other Vacuum Energy (w < -1)

Modification of GTR

Dark Energy

CDM : Dust like equation of state Pressure p=0 Energy density e > 0

Dark energy : p=w e; w < 0 (Ideally w= -1)

+ve energy -ve pressure

• Dark Energy

(a) emits no light

(b) it has large –ve pressure

(c) does not show its presence in galaxies

and cluster of galaxies, it must be smoothly

distributed

e c~ 10-47 GeV4 , So for DE ~ 0.7,

eDE ~ 10-48 GeV4 Natural Units

Natural Explanation : Vacuum energy density

with correct equation of state

Difficulties : higher energy scales

Planck era : ~ 1077 GeV4

GUT : ~ 1064 GeV4

Electroweak : ~ 108 GeV4

QCD : ~ 10-4 GeV4

Puzzle Why eDE is so small ???

Dark-Matter & Dark-Energy

Coloured Gluon exchange between coloured quarks

Overlapping nucleons

First order phase transition

T> Tc : coloured quarks and gluons in thermal equilibrium At Tc : bubbles of hadronic phase

grow in size and form an infinite chain of

connected bubbles

universe turns over to hadronic phase

in hadronic phase quark phase gets trapped in

large bubbles

Trapped false vacuum domains (TFVD) evolve to

Strange Quark Nugget (SQN)

For Stable SQNs A > 1044

Characteristics of SQN• large mass & non-relativistic

• large mutual separation ~ 300m at Temperature of 100Mev

• Discrete bodies in the background radiation fluid

• radiation pressure & Gravitational Potential due to other SQNs

Thermal and gravitational motion

• Density of SQNs decrease as t-3/2

mutual separation increases as t1/2

• mutual gravitational pull decreases as t-1

Force due to radiation decreases as T4 or t-2

gravitation will overcome radiation pressure

No. of MACHO TODAY

Total No. of MACHO ~ 1022-23

1013-14 MACHO in Milky Way Halo

T> Tc : coloured quarks and gluons in thermal equilibrium At Tc : bubbles of hadronic phase

grow in size and form an infinite chain of

connected bubbles

universe turns over to hadronic phase

in hadronic phase quark phase gets trapped in

large bubbles

Trapped domains evolve to SQN

What did we miss ???

Role of colour Charge

Assumption : Many body system

Colour is averaged

Only statistical degeneracy

Too Simplified ?????

Quantum Entanglement

• Typical quantum phenomena

Particles which are far apart seem to be influencing each other

Condition : Particles must have interacted with each other earlier

Measurement on one immediately specifies the other

Interacting particles always entangled

• Before P.T. Universe singlet

Wave functions of coloured objects entangled

Universe characterized by perturbative vacuum

During P.T. local colour neutral hadrons

Gradual decoherence of entangled wave functions

Proportionate reduction of vacuum energy

Provides latent heat of the transition

In Quantum mechanical sense

completion of quark-hadron P.T.

Complete decoherence of colour wave function

Entire vacuum energy disappear

Perturbative vacuum is replaced by non-perturbative one

Does that really happen ????

Stable nuggets

Colour neutral

All have integer baryon number

At the moment of formation quark number multiples of 3

Statistical system some residual colour

For colour neutrality : one or two residual quarks

End of cosmic quark-hadron phase transition

few coloured quarks separated in space

Colour wave functions are still entangled

Incomplete decoherence

Residual perturbative vacuum energy

Dark Energy ~ 10-48 GeV4

DE Constant

Matter density decreases as R-3

DE is dominant at late times

Dark-Matter & Dark-Energy

Strange Quark Matter & Orphan quarks

Consequence of Early Universe

Quark-Hadron Phase Transition

The Strange Universe

Collaborators

1. A. Bhattacharyya (Scottish Church College, Kolkata)

2. S. Banerjee (St. Xaviers College, Kolkata)

3. S. Raha (Bose Institute, Kolkata)

4. E. Ilgenfritz (RCNP, Osaka)

5. B. Sinha (VECC, Kolkata)

6. E. Takasugi (Osaka University, Osaka)

7. H. Toki (RCNP, Osaka)

Natural Units

Velocity of light c = = 1

Planck’s Constant

Temperature Energy Mass = MeV (106 eV)

Length Time = fm (10-15 m)

sec103 8 m

m103sec.1 8

J)106.1eV1(

1

sec.eV106.6

sec.J1005.1

19

16

34

Natural Units

Boltzman Constant k =1

Me = 0.511 MeV = 9.1 10-31 Kg

1 MeV (Temperature) = 1010 0K

1 M (Solar Mass) = 2 1030 Kg

back

No. of MACHO today

• T ~30K t ~ 4 X 1017 seconds

• Total baryons today from η = 10-10

• With CDM~ 0.3 ; baryon ~ 0.01

• Baryons in CDM = CDM / baryon X visible baryons

1.6 X 1079

• No. of MACHO = baryons in CDM / baryons in MACHO ~ 1022-23

• Milky Way visible mass ~ 1.6 X 1011M

2 X1068 baryons

2 X 10-9 of visible baryons inside

horizon

• Scaling 1013-14 MACHOs in Milky Way

Halo.

• Estimate : Bag model

• Bag pressure B difference between two vacuum

Beginning of P.T. vacuum energy B

This decreases with increasing decoherence

What will be Measure of entanglement

Measure : Volume Fraction of coloured degrees of freedom

Initially : fraction is unity complete entanglement

Finally : Small entanglement tiny but non-zero colour fraction

Amount of perturbative vacuum energy at any time= B X instantaneous colour fraction volume

Order of magnitude estimateFor percolating system : characteristic

critical fraction ~ 0.3 for high T phase Volume fraction in the form of TFVD

~ 0.3 Most likely length scale of TFVD ~ few cm

So at percolation time of 100 s No. of TFVD ~ Nq,O ~ 1018-20

Inter-TFVD separation ~ 0.01 cm

Order of magnitude estimate

Effective radius of orphan quark

qq= 1/9 pp ; pp ~ 20mb

rq,O=10-14 cm

Number of orphan quarks = Number of TFVD Nq,O ~ 1018-20

Coloured Volume fraction = Nq,O X (vq,O/VH) ~ 10-42 - 10-44

Residual vacuum energy =

Coloured Volume fraction X B

~ 10-44 X B

GeV)4

DE ~ 0.7

Alternative Prescription Problem with Inter-quark potential at large r Usual way- phenomenological string model

for quark-antiquark Richardson’s potential :

Linear potential in the large r limit

Our system : Dilute many body system of quarks (only)

Density dependent effective quark mass (DDQM) model

DDQM model mq ~ 1/nq

s = 1/log(1 + Q4/4)

Familiar perturbative form for large Q2.

V(r) = { (r)3 – 12/(r) }

For large r, V(r) ~ r3

Estimation of inter quark potential

nq,O Nq,O/VH

= (3/4) Nq,O / R3H

r = (3 nq,O/4)1/3

= RH / N1/3q,O

Potential energy density for inter-quark interaction is

V = nq,O V(r)/2 ~ (3/8) 4

Constant Independent of time

How to fix :

for hadronic bag ~ 100 MeV Our case appropriate length scale size of the smallest TFVD Stable Nuggets baryon density 1038 cm-3

Size ~ several cm Baryon density in Universe ~ 1030 cm-3 For TFVD with density 1030 cm-3 Size ~ 0.01cm

Other possible length scale Inter TFVD separation is of same order

~ 10-12 GeV Dark Energy ~ 10-48 GeV4