The First 380,000 Years in 10 Minutes

Introduction to Baryon Acoustic Oscillations

Sanha Cheong Adviser: Prof. Regina Demina Department of Physics and Astronomy University of Rochester [email protected] http://www.pas.rochester.edu/~scheong/

August 7, 2016 Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 1/13 I Started off from a singularity (infinite density and temperature) called the Big Bang

I Has been expanding ever since

I Homogeneous and isotropic universe (in large scale)

I Decreasing in density and temperature

Basic Cosmological Principle (and Assumptions)

What happened (and is happening) in the universe?

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 2/13 I Has been expanding ever since

I Homogeneous and isotropic universe (in large scale)

I Decreasing in density and temperature

Basic Cosmological Principle (and Assumptions)

What happened (and is happening) in the universe?

I Started off from a singularity (infinite density and temperature) called the Big Bang

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 2/13 I Homogeneous and isotropic universe (in large scale)

I Decreasing in density and temperature

Basic Cosmological Principle (and Assumptions)

What happened (and is happening) in the universe?

I Started off from a singularity (infinite density and temperature) called the Big Bang

I Has been expanding ever since

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 2/13 I Decreasing in density and temperature

Basic Cosmological Principle (and Assumptions)

What happened (and is happening) in the universe?

I Started off from a singularity (infinite density and temperature) called the Big Bang

I Has been expanding ever since

I Homogeneous and isotropic universe (in large scale)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 2/13 Basic Cosmological Principle (and Assumptions)

What happened (and is happening) in the universe?

I Started off from a singularity (infinite density and temperature) called the Big Bang

I Has been expanding ever since

I Homogeneous and isotropic universe (in large scale)

I Decreasing in density and temperature

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 2/13 I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 I ∼ 380, 000 yrs old = Photon Epoch

First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 First 380,000 Years of the Universe

First 10s of the universe...

I Before then is mostly theoretical

I Planck scale, inflation, SSB, etc.

I More in the regime of particle physics So, how is 10s old universe?

I Hot and dense plasma of (mostly H) nuclei and electrons (primordial plasma) and dark matter 4 I >> 10 K, still too hot to form neutral atoms

I Random over-dense regions (inhomogeneities)

I ∼ 380, 000 yrs old = Photon Epoch

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 3/13 This creates longitudinal waves in the primordial plasma: Baryon Acoustic Oscillations

Photon Epoch

Photons interact actively with the primordial plasma via Compton scattering. Photons and baryons are coupled. However, over-dense regions also have strong gravitational potential well due to dark matter.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 4/13 Photon Epoch

Photons interact actively with the primordial plasma via Compton scattering. Photons and baryons are coupled. However, over-dense regions also have strong gravitational potential well due to dark matter. This creates longitudinal waves in the primordial plasma: Baryon Acoustic Oscillations

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 4/13 Photon Epoch

Photons interact actively with the primordial plasma via Compton scattering. Photons and baryons are coupled. However, over-dense regions also have strong gravitational potential well due to dark matter. This creates longitudinal waves in the primordial plasma: Baryon Acoustic Oscillations

(a) Matter (b) Light (c) Density Plot

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 4/13 Photon Epoch

Photons interact actively with the primordial plasma via Compton scattering. Photons and baryons are coupled. However, over-dense regions also have strong gravitational potential well due to dark matter. This creates longitudinal waves in the primordial plasma: Baryon Acoustic Oscillations

(a) Matter (b) Light (c) Density Plot

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 4/13 Photon Epoch

Photons interact actively with the primordial plasma via Compton scattering. Photons and baryons are coupled. However, over-dense regions also have strong gravitational potential well due to dark matter. This creates longitudinal waves in the primordial plasma: Baryon Acoustic Oscillations

(a) Matter (b) Light (c) Density Plot

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 4/13 I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

But Wait! Recombination!

Recall that the universe is cooling down!

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

(a) Matter (b) Light (c) Density Plot Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

(a) Matter (b) Light (c) Density Plot Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

(a) Matter (b) Light (c) Density Plot Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

(a) Matter (b) Light (c) Density Plot Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 But Wait! Recombination!

Recall that the universe is cooling down!

I Down to ∼ 4000 K by 380,000 yrs old (z ≈ 1100)

I Cold enough to form neutral (hydrogen) atoms −→ Recombination!

I Neutral atoms do not interact electromagnetically −→ Matter is now decoupled from light.

(a) Matter (b) Light (c) Density Plot Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 5/13 I Any overdense region is much more likely to form galaxies

I Galaxy distribution is based upon the initial density distribution which includes BAO signals

Physical Significance: Large-scale Structure

BAO imprints a characteristic feature in the density distribution of neutral luminous matter in the universe (i.e., the ”frozen” sound horizon at the recombination). After recombination, gravity dominates.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 6/13 I Galaxy distribution is based upon the initial density distribution which includes BAO signals

Physical Significance: Large-scale Structure

BAO imprints a characteristic feature in the density distribution of neutral luminous matter in the universe (i.e., the ”frozen” sound horizon at the recombination). After recombination, gravity dominates.

I Any overdense region is much more likely to form galaxies

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 6/13 Physical Significance: Large-scale Structure

BAO imprints a characteristic feature in the density distribution of neutral luminous matter in the universe (i.e., the ”frozen” sound horizon at the recombination). After recombination, gravity dominates.

I Any overdense region is much more likely to form galaxies

I Galaxy distribution is based upon the initial density distribution which includes BAO signals

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 6/13 Physical Significance: Large-scale Structure

BAO imprints a characteristic feature in the density distribution of neutral luminous matter in the universe (i.e., the ”frozen” sound horizon at the recombination). After recombination, gravity dominates.

I Any overdense region is much more likely to form galaxies

I Galaxy distribution is based upon the initial density distribution which includes BAO signals

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 6/13 Z trec Z ∞ cs s = cs (1 + z)dt = dz 0 zrec H(z)   −1/2 where the sound speed c = 3 1 + 3ρb . s 4ργ This (not the comoving but the proper) distance evolves over time, and we can measure this evolution as a function of redshift based on observations. s Z z dz0 dA(z) = ∝ 0 and c∆z = H(z)s ∆θ 0 H(z ) Therefore, the sound horizon distance s provides a constraint for the cosmological expansion history. −→ Dark Energy!

Physical Significance: Standard Ruler

The sound horizon distance s provides a large fixed (co-moving) length scale: a standard ruler.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 7/13 This (not the comoving but the proper) distance evolves over time, and we can measure this evolution as a function of redshift based on observations. s Z z dz0 dA(z) = ∝ 0 and c∆z = H(z)s ∆θ 0 H(z ) Therefore, the sound horizon distance s provides a constraint for the cosmological expansion history. −→ Dark Energy!

Physical Significance: Standard Ruler

The sound horizon distance s provides a large fixed (co-moving) length scale: a standard ruler.

Z trec Z ∞ cs s = cs (1 + z)dt = dz 0 zrec H(z)   −1/2 where the sound speed c = 3 1 + 3ρb . s 4ργ

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 7/13 Therefore, the sound horizon distance s provides a constraint for the cosmological expansion history. −→ Dark Energy!

Physical Significance: Standard Ruler

The sound horizon distance s provides a large fixed (co-moving) length scale: a standard ruler.

Z trec Z ∞ cs s = cs (1 + z)dt = dz 0 zrec H(z)   −1/2 where the sound speed c = 3 1 + 3ρb . s 4ργ This (not the comoving but the proper) distance evolves over time, and we can measure this evolution as a function of redshift based on observations. s Z z dz0 dA(z) = ∝ 0 and c∆z = H(z)s ∆θ 0 H(z )

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 7/13 Physical Significance: Standard Ruler

The sound horizon distance s provides a large fixed (co-moving) length scale: a standard ruler.

Z trec Z ∞ cs s = cs (1 + z)dt = dz 0 zrec H(z)   −1/2 where the sound speed c = 3 1 + 3ρb . s 4ργ This (not the comoving but the proper) distance evolves over time, and we can measure this evolution as a function of redshift based on observations. s Z z dz0 dA(z) = ∝ 0 and c∆z = H(z)s ∆θ 0 H(z ) Therefore, the sound horizon distance s provides a constraint for the cosmological expansion history. −→ Dark Energy! Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 7/13 The Baryon Oscillation Spectroscopic Survey (BOSS) maps galaxies and quasars on the large scale.

I DR9: >200,000 galaxies in North, 0.43 < z < 0.7

I DR12: >800,000 CMASS (0.43 < z < 0.7) and >300,000 LOWZ (z < 0.43)

I DR13 (SDSS-IV): extended BOSS (eBOSS), further/deeper in z (∼1.1)

Observational Data: SDSS BOSS

The Sloan Digital Sky Survey (SDSS) is a long-term observational project. It recently entered its 4th phase. (DR13)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 8/13 I DR9: >200,000 galaxies in North, 0.43 < z < 0.7

I DR12: >800,000 CMASS (0.43 < z < 0.7) and >300,000 LOWZ (z < 0.43)

I DR13 (SDSS-IV): extended BOSS (eBOSS), further/deeper in z (∼1.1)

Observational Data: SDSS BOSS

The Sloan Digital Sky Survey (SDSS) is a long-term observational project. It recently entered its 4th phase. (DR13) The Baryon Oscillation Spectroscopic Survey (BOSS) maps galaxies and quasars on the large scale.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 8/13 I DR12: >800,000 CMASS (0.43 < z < 0.7) and >300,000 LOWZ (z < 0.43)

I DR13 (SDSS-IV): extended BOSS (eBOSS), further/deeper in z (∼1.1)

Observational Data: SDSS BOSS

The Sloan Digital Sky Survey (SDSS) is a long-term observational project. It recently entered its 4th phase. (DR13) The Baryon Oscillation Spectroscopic Survey (BOSS) maps galaxies and quasars on the large scale.

I DR9: >200,000 galaxies in North, 0.43 < z < 0.7

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 8/13 I DR13 (SDSS-IV): extended BOSS (eBOSS), further/deeper in z (∼1.1)

Observational Data: SDSS BOSS

The Sloan Digital Sky Survey (SDSS) is a long-term observational project. It recently entered its 4th phase. (DR13) The Baryon Oscillation Spectroscopic Survey (BOSS) maps galaxies and quasars on the large scale.

I DR9: >200,000 galaxies in North, 0.43 < z < 0.7

I DR12: >800,000 CMASS (0.43 < z < 0.7) and >300,000 LOWZ (z < 0.43)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 8/13 Observational Data: SDSS BOSS

The Sloan Digital Sky Survey (SDSS) is a long-term observational project. It recently entered its 4th phase. (DR13) The Baryon Oscillation Spectroscopic Survey (BOSS) maps galaxies and quasars on the large scale.

I DR9: >200,000 galaxies in North, 0.43 < z < 0.7

I DR12: >800,000 CMASS (0.43 < z < 0.7) and >300,000 LOWZ (z < 0.43)

I DR13 (SDSS-IV): extended BOSS (eBOSS), further/deeper in z (∼1.1)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 8/13 Real Data: Life Is Not So Simple...

SDSS-III DR9 North Data Galaxies

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 9/13 Real Data: Life Is Not So Simple...

Data-Data Galaxy Pairs DD(s) No peaks/bumps found... What now?

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 9/13 I Much more complicated: multiple ripples overlap

Figure: Simulations of BAO in 2D

I Other physics smears/blurs the BAO structure −→ The BAO structure is (relatively) very small.

Challenges in Looking for BAO

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 10/13 Figure: Simulations of BAO in 2D

I Other physics smears/blurs the BAO structure −→ The BAO structure is (relatively) very small.

Challenges in Looking for BAO

I Much more complicated: multiple ripples overlap

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 10/13 I Other physics smears/blurs the BAO structure −→ The BAO structure is (relatively) very small.

Challenges in Looking for BAO

I Much more complicated: multiple ripples overlap

Figure: Simulations of BAO in 2D

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 10/13 −→ The BAO structure is (relatively) very small.

Challenges in Looking for BAO

I Much more complicated: multiple ripples overlap

Figure: Simulations of BAO in 2D

I Other physics smears/blurs the BAO structure

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 10/13 Challenges in Looking for BAO

I Much more complicated: multiple ripples overlap

Figure: Simulations of BAO in 2D

I Other physics smears/blurs the BAO structure −→ The BAO structure is (relatively) very small.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 10/13 I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 −→ Need for quick calculation algorithm!

Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 Random Catalog

Utilize a random catalog to subtract the ”background.”

I Mimics data in large scale, but without BAO

I Compare DD against RR and look for excess galaxy pairs DD DD−2DR+RR I DD − RR, RR , RR , etc. However, this poses a computational problem.

I The random catalog needs to be huge: nR & 10nD

I RR calculation becomes the bottleneck of the calculation

I The amount of data available is skyrocketing −→ Need for quick calculation algorithm!

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 11/13 Correlation Functions

I DD(s), DR(s), and RR(s)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 12/13 Correlation Functions

I DD-RR

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 12/13 Correlation Functions

I Other correlation functions DD(s)−2DR(s)+RR(s) I ξ(s) = RR(s)

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 12/13 References

I http: //www.astro.ucla.edu/~wright/BAO-cosmology.html

I http://w.astro.berkeley.edu/~mwhite/bao/

I http://apod.nasa.gov/apod/ap140120.html

I http://galaxies-cosmology-2015.wikidot.com/ baryon-acoustic-oscillations

Introduction to Baryon Acoustic Oscillations Sanha Cheong, UR 13/13