Section 1
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Cosmology Beyond the Standard Model
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
1/21
Section 1
Section 2
Section 3
What is Cosmology?
We’re in the Astronomy Unit so...
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
2/21
Section 1
Section 2
Section 3
What is Cosmology?
?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
3/21
Section 1
Section 2
Section 3
What is Cosmology?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
4/21
Section 1
Section 2
Section 3
What is Cosmology?
?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
5/21
Section 1
Section 2
Section 3
What is Cosmology?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
6/21
Section 1
Section 2
Section 3
What is Cosmology?
?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
7/21
Section 1
Section 2
Section 3
What is Cosmology?
Well... not really...
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
8/21
Section 1
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Section 3
What is Cosmology?
Yes, but one ”slice in time”...
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
9/21
Section 1
Section 2
Section 3
What is Cosmology?
Evolution though time.
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
10/21
Section 1
Section 2
Section 3
What is the Standard Model of Cosmology (ΛCDM)?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
11/21
Section 1
Section 2
Section 3
My work to date - beyond ΛCDM
• First project:
• Analytical work...
• Theoretical work performed mathematically - equation manipulation
and construction
• Non standard cosmology - Conserved Quantities and the Evolution
of Perturbations in Lemaı̂tre-Tolman-Bondi Cosmology (LTB)
• But what if the universe is not homogeneous on large scales?
• What if the universe is inhomogeneous on some larger scale?
• WHAT IF THE APPARENT ACCELERATING EXPANSION
OF THE UNIVERSE IS IN FACT DISTANCE DEPENDENT
EXPANSION?
• What if the growth of structure in the universe is governed by
perturbations around an inhomogeneous background
cosmology?
• Simplest of these to investigate: Lemaı̂tre-Tolman-Bondi
Cosmology Cosmology Beyond the Standard Model
Alex Leithes (QMUL)
QMUL Outreach 2015
12/21
Section 1
Section 2
Section 3
My work to date - beyond ΛCDM
As you can tell from the mass of text above quite technical stuff, plus the
arxiv description for the paper, ”16 pages, 0 figures”...
Conclusion and Further Research
•
ζ̇SMTP =
HX + 2HY
δPnad
3ρ̄
• Research already extended to other spacetimes
i.e. ζ̇SMTP already extended to Lemaitre and FRW
• ζSMTP can provide a useful analytical check for numerical codes in
perturbed LTB/inhomogeneous spacetimes...
as described in 1412.3012 Bartelmann et al.
• e.g. potentially useful in study of structure formation in large voids
(see e.g. 1411.1828 Das et al.)
arXiv:1403.7661 - but...
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
13/21
Section 1
Section 2
Section 3
My work to date - beyond ΛCDM
... did get to travel to COSMO 2014 in Chicago to talk about my work :)
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
14/21
Section 1
Section 2
Section 3
My work to date - beyond ΛCDM
• Second project:
• Numerical work...
• Small amount of analytical work plus loads of coding...
• Non standard cosmology - Coupled Quintessence (Not Λ)!
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
15/21
Section 1
Section 2
Section 3
Beyond Lambda - Why Coupled Quintessence?
Why Coupled Quintessence?
• Late time accelerated expansion - simplest solution: Cosmological Constant, Λ,
“Dark Energy?” - problems e.g. coincidence
• Alternatives: one or more scalar fields - non-constant or ”dynamical” Dark
Energy
• Coupled Quintessence: Canonical scalar field(s), φ, with potential V (φ),
interacting gravitationally with all components, and through couplings between
DE and CDM components - solves problems e.g. coincidence (Quintessence
alone), breaking tracking (when Coupled) - Coupled = Interacting
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
16/21
Section 1
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Section 3
Beyond Lambda - Why Coupled Quintessence?
Questions of Coupled Quintessence
• Need a generalised code to test any given coupled quintessence
model and allow comparison with observations
• We are developing code, PYESSENCE, to do this
• Background evolution of a model must match observations (CMB,
SN data)
• If background satisfies this, is the perturbed model stable (under
what range of couplings/no. of fields etc.)?
• If perturbation are stable do they match observations from large
scale structure surveys e.g. BOSS, DES, eBOSS, DESI, Euclid?
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
17/21
Section 1
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Section 3
PYESSENCE code - Work to date
Work to date
• For first time plotted evolution of stable perturbations to this 2
fluid, 2 field, sum of exponentials model, for a point in coupling
constant space, in fourier space. For the plot below k = H0
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
18/21
Section 1
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Section 3
Results and future work
Results and future work
• Forthcoming paper to present these results in full, with maps of
stable regions of couplings parameter space, and release
PYESSENCE code for community
• Constrain models through stability
• Constrain models through comparison with LSS surveys (Euclid etc.)
and again...
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
19/21
Section 1
Section 2
Section 3
Results and future work
... got to travel to Sicily to talk about my work... :)
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
20/21
Section 1
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Section 3
Results and future work
...and win a prize! :D
Thank you!
Alex Leithes (QMUL)
Cosmology Beyond the Standard Model
QMUL Outreach 2015
21/21