Recent developments in neutrino for the layperson

Sunny Vagnozzi

The Oskar Klein Centre for Cosmoparticle Physics, Stockholm University

[email protected]

PhD thesis discussion Stockholm, 10 June 2019

1 / 27 D’o`uvenons-nous? Que sommes-nous ? O`uallons-nous?

Courtesy of Paul Gauguin

2 / 27 The oldest questions...

Where do we come from? What are we made of ? Where are we going?

3 / 27 ...and the modern versions of these questions

What were the Universe’s initial conditions? Where do we come from? −→ What is the Universe What are we made of ? −→ made of ? Where are we going? −→ How will the Universe evolve?

4 / 27 Where do we come from?

Cosmic inflation aka (Hot) Big Bang?

5 / 27 What are we made of?

Mostly dark stuff (and a bit of neutrinos)

6 / 27 Where are we going?

Depends on what is?

7 / 27 Lots of astrophysical and cosmological data to test theories for the origin/composition/fate of the Universe:

8 / 27 Neutrinos

9 / 27 Neutrino masses

10 / 27 Neutrino mass ordering

11 / 27 Paper I

Sunny Vagnozzi, Elena Giusarma, Olga Mena, Katie Freese, Martina Gerbino, Shirley Ho, Massimiliano Lattanzi, Phys. Rev. D 96 (2017) 123503 [arXiv:1701.08172] What does current data tell us about the neutrino mass scale and mass ordering? How to quantify how much the normal ordering is favoured?

12 / 27 Paper I

Even a small amount of massive neutrinos leaves a huge trace in the distribution of on the largest observables scales

13 / 27 Paper I

1 M < kg ν 10000000000000000000000000000000000000

14 / 27 Paper II

Elena Giusarma, Sunny Vagnozzi, Shirley Ho, Simone Ferraro, Katie Freese, Rocky Kamen-Rubio, Kam-Biu Luk, Phys. Rev. D 98 (2018) 123526 [arXiv:1802.08694] Scale-dependent bias: can we nail it through CMB lensing-galaxy cross-correlations and learn more about neutrinos?

15 / 27 Paper II

Galaxy bias

16 / 27 CMB lensing-galaxy cross-correlation

×

17 / 27 Paper III

Sunny Vagnozzi, Thejs Brinckmann, Maria Archidiacono, Katie Freese, Martina Gerbino, Julien Lesgourgues, Tim Sprenger, JCAP 1809 (2018) 001 [arXiv:1807.04672] Scale-dependent galaxy bias induced by neutrinos: why we should worry, and a simple correction implemented in CLASS

18 / 27 Paper III

19 / 27 Paper III

NISDB correction NISDB correction No NISDB correction No NISDB correction 1.0

0.8

x 0.966 a

m 0.6 P s / n P 0.960 0.4

0.12

0.2 )

V 0.08 e (

0.0 ν 0.04 M 0.00 0.04 0.08 0.12 0.16 0.00 M (eV) 0.1197 0.1211 0.960 0.966 0.00 0.04 0.08 0.12 ωcdm ns Mν (eV)

20 / 27 Paper IV

Sunny Vagnozzi, Suhail Dhawan, Martina Gerbino, Katie Freese, Ariel Goobar, Olga Mena, Phys. Rev. D 98 (2018) 083501 [arXiv:1801.08553] Can the neutrino mass ordering and laboratory experiments tell us something about dark energy and the fate of the Universe (“Where are we going?”)?

21 / 27 Paper IV

22 / 27 Paper IV

Rules of the game: Choose your favourite dark energy model (Goliath).

Compute upper limit on Mν using only cosmological information (David). If limit does not contract lower limit from oscillations (0.06 eV), your model is not ruled out (yet), else you have a problem!

23 / 27 Paper V

Martina Gerbino, Katie Freese, Sunny Vagnozzi, Massimiliano Lattanzi, Olga Mena, Elena Giusarma, Shirley Ho, Phys. Rev. D 95 (2017) 043512 [arXiv:1610.08830] Neutrinos as a nuisance: can they mess up our conclusions about inflation and the initial conditions of the Universe (“Where do we come from?”)?

24 / 27 Paper V

...something (apparently) messes Big Bang sets initial conditions for them up? the Universe...

25 / 27 Paper V

TT+lowP

ΛCDM +BAO

TT+lowP

ΛCDM + r +BK14+BAO

TT+lowP

ΛCDM + Mν +BAO

TT+lowP

+BK14+BAO ΛCDM + r + Mν

0.940 0.945 0.950 0.955 0.960 0.965 0.970 0.975 0.980 nS 26 / 27 Sunny Vagnozzi The three neutrinos are ghostly elementary particles that exist all across the Universe. Though every second billions of them fly through us, they Weigh them all! are extremely hard to detect. We used to think they had no mass, but recently discovered that in fact they have a tiny mass. The quest for the Cosmological searches for the neutrino mass scale and mass ordering neutrino mass scale and mass ordering (specifying how the three masses are distributed) is an extremely exciting one, and will open the Weigh all! them door towards new physics operating at energy scales we can only ever Sunny Vagnozzi dream of reaching on Earth. This thesis explores the use of measurements of the Cosmic Microwave Background (the oldest light reaching us, a snapshot of the infant Universe) and maps of millions of galaxies to go after the neutrino mass scale and mass ordering. Neutrinos might teach us something about the mysterious dark energy powering the accelerated expansion of the Universe, or about cosmic inflation, which seeded the initial conditions for the Universe. Though extremely baffling, neutrinos are also an exceptionally exciting area of research, and cosmological observations promise to Thank you! reveal a great deal about these elusive particles in the next years.

Sunny Vagnozzi Originally from Italy, before doing his PhD at Stockholm University he earned degrees in Physics at the University of Trento (BSc, 2012) and the University of Melbourne (MSc, 2014). He works at the interface of cosmology and astroparticle physics.

ISBN ISBN 978-91-7797-727-8

Department of Physics

Doctoral Thesis in Theoretical Physics at Stockholm University, Sweden 2019 27 / 27