DDays - galaxies & cosmology

Antonello Calabro

Charles-Antoine Claveau

Maximilien Franco

Morgan Schmitz

How did we get here?Study of the evolution of the Universe

and its components

How did we get here?Study of the evolution of the Universe

and its components

The Universe as we (don’t really) understand it

26.8%

68.3%

4.9%

The Universe as we (don’t really) understand it

26.8%

4.9%

68.3%

Cosmological probes

LensingBaryon Acoustic Oscillations

Galactic scales

Merger-starburst connection

Astronomy in the good old days

+ = Science!

Astrophysics and cosmology today

JWST

ALMA

EUCLID

DESI

now

2019

2020

2021

2022

Astrophysics and cosmology today

JWST

ALMA

EUCLID

DESI

now

2019

2020

2021

2022

Astrophysics and cosmology today

Instruments Data processing Science!

Astrophysics and cosmology today

Instruments Data processing Science!

Charles-Antoine

Instruments Data processing Science!

Dark Energy Spectroscopic Instrument - DESIA wide & deep spectroscopic survey of a large volume of the Universe

Mayall 4-m telescope at Kitt Peak in Arizona

5000-fiber multi-object spectrograph

Up to 5 year Dark Energy survey (start in 2020)

Spectral range: 360 nm < z < 980 nm

Sky area: 14000 square degrees

Broad range of target classes LRG, ELG, QSO

Broad redshift range: 0.5 < z < 4.0

Number of redshifts: 25 million

8.0

Spectrograph & Cryostats

Each spectro module receives 500 fibers& consists of three arms coveringwavelength range from 360 nm to 980 nm

CEA deliverables:

- 30 Cryostats

- Cryostat Slow ControlElectronics

- Cryostat Vacuum pumpstations

In charge of:

- Integration and alignment ofCCD sensor, LPT & ionic pump

- Test of vacuum &temperature regulation

- Check of CCD positioning

Quasar Target Selection

DESI needs targets to measure their spectrum

Dedicated massive imaging surveys (BASS, MzLS,DECaLS) in several photometric bansd, combined withinfrared bands from WISE satellite

Development of target selection algorithms based on thephotometric & morphology properties of the objects to beclassified

Machine learning approach with Random Forest

Target density budget of 260 deg-2 with a successrate of:

z < 2.1 : 120 deg-2

z > 2.1 : 50 deg-2

Optical BenchCheck of the CCD lateral position and roll angle

Working principle: Very precisely project orthogonally a regular grid of spots on the CCD plane

Simulations performed to demonstrate its feasibility and go over all sources of error

Software pipeline implemented to process CCD images

In collaboration with Erwann Aubernon, SEDI

Morgan

Instruments Data processing Science!

Gravitational lensing

Credit: NASA, ESA & L. Calçada

Strong lensing

Credit: ESA/Hubble & NASA Credit: NASA/ESA

Weak lensing

PSF Effect

PSF Effect

PSF Effect

Optimal transport and PSF estimation

Maximilien

Instruments Data processing Science!

Multi-Wavelengths surveyImpossible d’afficher l’image.

Drop of the gas content Or

Drop of the star formation efficiency

Antonello

Instruments Data processing Science!

Impossible d’afficher l’image.Morphological transformation of gas rich spirals/disks into gas-poor massive ellipticals

Credit: Hubble/GalaxyZoo

Hubble Legacy Archive - NGC 2623

Early-type galaxies

Late-type galaxies

Impossible d’afficher l’image.

Impossible d’afficher l’image.

M101

NGC 1365ESO 325-G004

M87

The Toomre sequence of mergers (Toomre & Toomre 1972)

compact (1 kpc)heavily obscured

Starbursts (high star-formation rate)

Motivations :1. The dust attenuation decreases at longer wavelengths

390 nm 700 nm

Wavelength

Flux

Near-infrared (0.7-5 micron)

UV

near-IR

new

sta

rs

Motivations :

2. pilot study with enormous potential : with JWST --> fainter lines and much higher redshift3. No survey has yet tried to systematically track NIR lines at high-z

TEST THE MERGER SCENARIO

Constrain the dust attenuation of the starburst core

Trace the rapid metal-enrichment of the dust-obscured starburst core

Impossible d’afficher l’image.

Discovery of a sequence of Starbursts with extreme obscurations

increasing dust obscuration

Median Av = 9 mag (x 4000 suppression of light)

Key results :

● Dust-geometry : dust and stars are homogeneously mixed, foreground dust screen models do not work

● Starbursts at z ~ 0.7 have extremely obscured cores → strong indication that they are merger driven

● Dust obscuration is a powerful tool to identify mergers at high redshift● Wide range of attenuations 1 < Av < 30 mag, correlate with other physical

properties ([NII]/H𝛂𝛂, EWlines , size). We suggest that these correlations are tracing an evolutionary sequence of mergers

Future work :● JWST : NIR and MIR spectroscopic survey of starbursts up to z ~ 7 , resolved

properties of dust attenuation (role of the extended emission ?)● ALMA : CO observations to trace the instantaneous SFR (the sequence of

obscurations is due to SFR timescale effects ?)

Conclusion

CEA is involved in many experiments which cover a wide and complete range ofcosmological topics :

- With a multi-scale approach- With a multi-wavelength approach- From instrumental part to data analysis

Much more to come once JWST, Euclid, DESI … operationals