Quasibaryonic Matter inCosmology

Shibaji Banerjee

Dept. of Physics,St. Xavier’s College (Autonomous),

Kolkata

March 10, 2011

ARIES Training School in Observational Astronomy-2011,March 07 - March 11, 2011

ARIES, Nainital.

The Ground state

Baryonic MatterThe Status of Baryonic Matter

• Observation→ The Universe is flat on the large scale.• An inventory of all baryonic matter in stellar material and

dark gas is totally insufficient to ensure that the universe isflat on the large scale. It can amount to at most 10% of thenecessary matter density.

Baryonic MatterThe Status of Baryonic Matter

• Observation→ The Universe is flat on the large scale.

• An inventory of all baryonic matter in stellar material anddark gas is totally insufficient to ensure that the universe isflat on the large scale. It can amount to at most 10% of thenecessary matter density.

Baryonic MatterThe Status of Baryonic Matter

• Observation→ The Universe is flat on the large scale.• An inventory of all baryonic matter in stellar material and

dark gas is totally insufficient to ensure that the universe isflat on the large scale. It can amount to at most 10% of thenecessary matter density.

Matter in the darkMatter, as we know it, is extremely rare in this Universe.

• Thus most of the matterin the universe belongsto an unknown variety,unavailable to directmethods of visualinspection.

• Halo dark matter, anunknown variety?

Matter in the darkMatter, as we know it, is extremely rare in this Universe.

• Thus most of the matterin the universe belongsto an unknown variety,unavailable to directmethods of visualinspection.

• Halo dark matter, anunknown variety?

Matter in the darkMatter, as we know it, is extremely rare in this Universe.

• Thus most of the matterin the universe belongsto an unknown variety,unavailable to directmethods of visualinspection.

• Halo dark matter, anunknown variety?

Matter in the darkMatter, as we know it, is extremely rare in this Universe.

• Thus most of the matterin the universe belongsto an unknown variety,unavailable to directmethods of visualinspection.

• Halo dark matter, anunknown variety?

v2 ∝ GM(r)

r

Matter in the darkMatter, as we know it, is extremely rare in this Universe.

• Thus most of the matterin the universe belongsto an unknown variety,unavailable to directmethods of visualinspection.

• Halo dark matter, anunknown variety?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?• What are these dark lenses made of ?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?• What are these dark lenses made of ?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?• What are these dark lenses made of ?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?• What are these dark lenses made of ?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?

• What are these dark lenses made of ?

The nature of halo dark matter• Gravitational

Microlensingexperiments

• The MachoCollaboration, Alcockand Sutherland in1999-2000

• Ultra-compact Objects detected in the milky way halotowards the LMC

• 17 of them with mass ranging between 0.15 -0.95 M�

• Brown Dwarfs ?• What are these dark lenses made of ?

An uncorrelated mystery?• Exotic cosmic ray

events.

• Unuzualz

Aratio

• Unusuallyhighpenetrability

• What are theorigin of thesecosmic rayevents?

An uncorrelated mystery?• Exotic cosmic ray

events.• Unuzual

z

Aratio

• Unusuallyhighpenetrability

• What are theorigin of thesecosmic rayevents?

An uncorrelated mystery?• Exotic cosmic ray

events.• Unuzual

z

Aratio

• Unusuallyhighpenetrability

• What are theorigin of thesecosmic rayevents?

An uncorrelated mystery?• Exotic cosmic ray

events.• Unuzual

z

Aratio

• Unusuallyhighpenetrability

• What are theorigin of thesecosmic rayevents?

The connectionStrange MatterHypothesisWitten’s conjecture(1984): The moststable form of mattermay not a be aparticular isotope likeFe-56, but 3N quarksconfined within largehadronic bags.

The connectionStrange MatterHypothesis• The quarks roam

about freelywithin a bagwhich confinesthem as a whole.

• Quark matterblobs are knownas QNs (QuarkNuggets)

The connectionStrange MatterHypothesis• Quark matter is

not stable inabsence of thestrange quark.

• The strangequark makes anextra Fermi wellavailable to thequarks and helpsto lower theenergy of theconfiguration.

The ConnectionStrange MatterHypothesis• Strange Quark

matter (SQM) isstable comparedto normal nuclearmatter.

• SQM originate inthe cosmic QCDphase transitionin themicrosecond eraof the universe.

SQNs after the phase transition• The trapped domains turned into SQNs of a specific size.

• The number of SQNs multiplied as the universe expandedand encroached more real estate within its territory.

• It was natural for them to collide and form more massiveand larger blobs, but . . .

SQNs after the phase transition• The trapped domains turned into SQNs of a specific size.• The number of SQNs multiplied as the universe expanded

and encroached more real estate within its territory.

• It was natural for them to collide and form more massiveand larger blobs, but . . .

SQNs after the phase transition• The trapped domains turned into SQNs of a specific size.• The number of SQNs multiplied as the universe expanded

and encroached more real estate within its territory.• It was natural for them to collide and form more massive

and larger blobs, but . . .

Coalescence of nuggets• The radiation pressure prevented them from coming too

close.• They had to wait till the universe grew cold enough with

time, and then, smashed all together to form a really

H-U-G-E blob(QBOs).

What if they are the MACHOs ?• The number of coalesced SQN’s increased due to the

scale factor expansion of the universe.• At that stage, they were too far apart to collide.• With the passage of time they distributed themselves

uniformly in the Universe, and the galactic halo is a goodhiding place as well as any.

• We looked into their expected size and population densityand compared them to the existing data. Using a naiveinverse square spherical model comprising such objectsupto the LMC, we obtained an optical depth of 10−6 – 10−7

which compares reasonably well with the values obtainedby Sutherland and Alcock1.

1MNRAS 2003, 340, 284, Banerjee, Bhattacharya, Raha, Sinha, Toki

What if the MACHOS or StrangeStars collided among themselves ?

• Maximum mass of Quark Stars2.

Rmax =3

16

1√πGB

• Strangelets:The splinters of the collision process ?• Small Lumps of SQM can be stable as well.

2JPhys, 200, G26 L1, Banerjee, Ghosh, Raha

Strangelets in Terrestrial Atmosphere• If strangelets ever visit us, they

would grow in size as they comedown to find a resting place.

• Simulation of strangeletpropagation in the terrestrialatmosphere leads to neareyeball match to the exoticcosmic ray data.

γmsd~v

dt= −ms~g+q(~v× ~B)−γ~v

(dmsn

dt+dmsp

dt

)−ms~v

dγ

dt−f (v)√

3~v

where,dmsp

dt= fpn

dmsn

dtand where,

fpn =R2

s

(rn +Rs)2

(1− 1

E

Zse2

4πε0Rs

)

Strangelets in the TerrestrialAtmosphere• If strangelets ever visit us, they

would grow in size as they comedown to find a resting place.

• Simulation of strangeletpropagation in the terrestrialatmosphere leads to neareyeball match to the exoticcosmic ray dataa

• Experiments to detectstrangelets are in progress.

aPRL,2000,85 1384, Banerjee, Ghosh,Raha, Syam

Strangelets in the TerrestrialAtmosphere• If strangelets ever visit us, they

would grow in size as they comedown to find a resting place.

• Simulation of strangeletpropagation in the terrestrialatmosphere leads to neareyeball match to the exoticcosmic ray dataa

• Experiments to detectstrangelets are in progress.

aPRL,2000,85 1384, Banerjee, Ghosh,Raha, Syam

Synopsis

• The existence of dark matter can be explained well withinthe encompass of standard physics without inviting anyexotic proposition.

Conclusion• Observable evidence for strangelets would reinforce QCD

dictions• It is strange that the strange matter hypothesis can lead to

the most non-strange explanation for the existence andnature of dark matter.

• The Universe is strange, but (may be) simple !

Acknowledgements• A. Bhattacharyya (Kolkata University)• S.K. Ghosh (Bose Institute, Kolkata)• S. Raha (Bose Institute, Kolkata)• E. Ilgenfritz (RCNP, Osaka)• B. Sinha (VECC, Kolkata)• D.Syam (Barasat Govt. College, Kolkate)• E. Takasugi (Osaka University, Osaka)• H. Toki (RCNP, Osaka)

• ARIES