New Frontiers in LAE Science with MUSELyman α as an Astrophysical Tool

Christian Herenz

Leibniz-Institut fur Astrophysik in Potsdam (AIP)PhD Student

Supervisor: L. Wisotzki

September 13th, 2013

MUSE Science Team

MUSE - 2nd Generation VLT InstrumentMUSE - Multi Unit Spectroscopic Explorer - 7 European Institutes -PI: Roland Bacon (CRAL)

Instrument Integral Field SpectrographType Image SlicerTelescope VLT UT-4 “Yepun”No. of IFU units 24Detectors 24×4k×4k e2v CCDsSpectral Range (465) 480 - 930 nmzLyα (2.8) 2.95 - 6.6Spectral Resolution 1750@465nm - 3750@930nmField of View 1′ × 1′ (Wide Field Mode)Spatial Sampling 0.2′′ × 0.2′′ (Wide Field Mode)

Feb 2014 - First Light (Feb 7.- Feb 21. Commissioning),∼ May - Jul 2014: Science VerificationSep 2014 - Start of GTO (& GO)

MUSE Reality

MUSE CAD

MUSE (simulated) Raw Data24× (n× Science Exp. + Arc +Flat + Standard(s) + BIAS)

Data Reduction System(developed at AIP):

Sky Subtracted “Datacube”’

→ dim(x , y , z) ≈(300,300,3600) voxel

Datacube-Size:1.5 GB Data

+ 1.5 GB Variance

MUSE - Unique Instrument for LAE Surveys IBest contrast for line emission.

(Fig. by courtesy of L. Wisotzki.)

FLyα ∼ 10−17erg s−1 cm−2 z∼6⇐⇒ SFRLyα ∼ 1M� yr−1

MUSE - Unique Instrument for LAE Surveys IBest contrast for line emission.

Detection Limit of current NB imaging studies

(Fig. by courtesy of L. Wisotzki.)

FLyα ∼ 10−17erg s−1 cm−2 z∼6⇐⇒ SFRLyα ∼ 1M� yr−1

MUSE - Unique Instrument for LAE Surveys IIAccurate EWLyα measurement at faint Lyα fluxes.

(Fig

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MUSE - Unique Instrument for LAE Surveys IIAccurate EWLyα measurement at faint Lyα fluxes.

(Fig

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∼10

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Detection of LAEs in MUSE Datacubes IMatched Filtering in 3D

Matched Filtering Theorem:S/N of a source in a givendataset is maximized whendataset is cross-correlated withexpected signal (template) ofsource.

• 3D dataset (datacube)→3D template

• λ-dependent Moffat(x,y) ⊗λ-dependent Gaussianλ(vFWHM fix) -approximates velocitybroadening in the spectral& PSF broadening in thespatial domain

Detection of LAEs in MUSE Datacubes II

• Detection S/N Cube• Thresholding• Catalog• Measure (Flux / EW etc.)

120 140 160 180 200xpix.

40

60

80

100

120

y pix.

on-band

120 140 160 180 200xpix.

40

60

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100

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y pix.

off-band

4.5

3.0

1.5

0.0

1.5

3.0

4.5

ID 4 (DATACUBE_FINAL_skysub_zap_zcut_spat1.5_wavel300_sncut20.0.cat) DetSN: 90.44 λ=5412.052

5380 5390 5400 5410 5420 5430 5440λ[

◦A]

0

100

200

300

400

500

Fλ/1

020[e

rg/s/c

m2/◦ A]

Ap.-Size: 3^2 px. Ap.-Size: 4^2 px. Ap.-Size: 8^2 px. Ap.-Size: 20^2 px.

ID 4 (DATACUBE_FINAL_skysub_zap_zcut_spat1.5_wavel300_sncut20.0.cat), DetSN:90.44, λ=5412.052◦A

Reliability of Detection Algorithm

R =T

T + F' P − N

PT . . . true positives, F . . . false positivesP . . . detections, N . . . detections in negated cube

3.0 3.5 4.0 4.5 5.0 5.5 6.0(S/N)det

0.0

0.2

0.4

0.6

0.8

1.0

Relia

bili

ty R

R (v=250km/s)R (v=350km/s)

101

102

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104

105

num

ber

of

dete

ctio

ns

number of detections

texp. = 2 hFWHM = 0.8 ′′

Reliability of Detection Algorithm

R =T

T + F' P − N

PT . . . true positives, F . . . false positivesP . . . detections, N . . . detections in negated cube

3.0 3.5 4.0 4.5 5.0 5.5 6.0(S/N)det

0.0

0.2

0.4

0.6

0.8

1.0

Relia

bili

ty R

R (v=250km/s)R (v=350km/s)

101

102

103

104

105

num

ber

of

dete

ctio

ns

number of detections

texp. = 10 hFWHM = 1.0 ′′

Summary & Future Work

Summary

• MUSE will enable the exploration of uncharted territories inthe observable parameter space of LAEs (FLyα & EWLyα).

• First Light: Feb 2014 - First Results: Hopefully before theend of my PHD (∼ End of 2014).

• 3D Matched Filtering is a reliable & robust method to huntfor LAEs in MUSE Datasets (Datacubes).

Future Work

• Classification• Flux measurement & EWLyα measurement using HUDF /

XDF images (together with Josephine Kerutt - MasterStudent at AIP)

• Release Emission Line Source Detection Software forCommunity