Stacking the Cosmic Web in Fluorescent Lyman-α emission

with MUSE

Sofia G. Gallego, Sebastiano Cantalupo, Simon Lilly, Raffaella Marino, Gabriele Pezzulli, Joop Schaye, Lutz Wisotzki, Roland Bacon,

Hanae Inami, Mohammad Akhlaghi, Sandro Tacchella, Johan Richard, Nicolas Bouche, Matthias Steinmetz & Marcella Carollo

Durham, June 20 2017

What Matter(s) Around Galaxies?

- Cosmological simulations show filaments connecting galaxies

Cantalupo+2012

- If filaments are LLS their Lyɑ emission constrains the UVB

- Expected SB from UVB fluorescence 1.14x10-20 erg/s/cm2/arcsec2 (z=3.5)

- Current available observations are not deep enough to reach those limits

- Oriented stacking along galaxies increase S/N and may show filamentary emission

How can we detect the Cosmic Web?

Ly⍺ z=3

Durham, June 20 2017

• Are galaxies connected by LLS filaments?

• How bright is the UVB?

• Is the CGM at kpc scales also “oriented” like the Cosmic Web?

• How the questions above depend on galaxy properties?

Key Questions

Durham, June 20 2017

• What is the origin and fate of the CGM? • What are the morphological and

physical properties of the CGM? • What are the physical processes that

shape the CGM on both large (kpc) and small (pc) scales?

• What is the relation between the CGM and galaxy properties?

• How does the CGM evolve and what can we learn by comparing different epochs and tracers?

Initial WMAG2017

Stacking Procedure- Lyman alpha emitters (LAEs) selected from the MUSE deep fields (1’x1’)

HDFS (89, ~26 hrs) + UDF10 (158, ~29 hrs)

- Select pairs of LAEs within 0.5 < cMpc < 20, θ > 16” and 2.9 < z < 4 (195)

- Equivalently, select LAEs with a “neighbor” within that range (390)

Durham, June 20 2017

Gallego+17

Stacking Procedure - Coordinate Transformation

Gallego+17

Let’s look at the filaments!

Results

Gallego+17

ResultsStack - Random OrientationsStack Full Sample

Results

Durham, June 20 2017

Gallego+17

Results

~18x deeper than the cubes!

SB 2σ between 6” and 12”: 0.44e-20 cgs

SB HM12: 1.14e-20 cgs

Durham, June 20 2017

Gallego+17

ResultsResults

Durham, June 20 2017

Results: Split Sample

Gallego+17

Discussion

• The lack of emission at IGM scales implies: i) UVB is a factor of 3 or more below expectations at z~3.5(very unlikely), OR ii) IGM filaments are not LLS, OR iii) At least 2/3 of our subcubes do not have LLS filaments (assuming HM12 UVB)

• Possible origins for the “statistical excess” CGM emission? • Satellite galaxies • Galaxy fluorescence • Ly⍺ scattering from the central galaxies

Durham, June 20 2017

• The lack of emission at IGM scales implies: i) UVB is a factor of 3 or more below expectations at z~3.5(very unlikely), OR ii) IGM filaments are not LLS, OR iii) At least 2/3 of our subcubes do not have LLS filaments (assuming HM12 UVB)

• Possible origins for the “statistical excess” CGM emission? • Satellite galaxies • Galaxy fluorescence • Ly⍺ scattering from the central galaxies

Discussion

Durham, June 20 2017

Imply higher densities on the direction of the neighbours!

Summary

• We perform an oriented stacking of LAEs in the direction of neighbouring galaxies with MUSE

• No emission is found on IGM scales (>30 kpc) • Excess of emission is found on CGM scales (<30 kpc),

it seems stronger for LAEs with more neighbours and independent of other galaxy properties (luminosity, redshift, distance to neighbours). → Satellites, galaxy fluorescence or Ly⍺ scattering?

Future Directions: • Extend analysis to UDF Mosaic:

1/3 fainter but 3x more LAEs and bigger f.o.v. • Simulations

Durham, June 20 2017

Key Questions • What are the morphological and physical properties of the CGM?

• What are the physical processes that shape the CGM on both

large (kpc) and small (pc) scales?

• What is the relation between the CGM and galaxy properties?