MegaSa ura : a spectroscopic sample of lensed starbursts at Cosmic - - PowerPoint PPT Presentation

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Apr 27, 2023 113 likes •419 views

MegaSa ura : a spectroscopic sample of lensed starbursts at Cosmic Noon and one particularly interesting member T. E. Rivera-Thorsen 1 with H akon Dahle 1 , Max Gr onke 2 , Matt Bayliss 3 , Jane Rigby 4 , the SGAS collaboration March 26,

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SLIDE 1

MegaSaura: a spectroscopic sample of lensed starbursts at Cosmic Noon — and one particularly interesting member

  • T. E. Rivera-Thorsen1 with H˚

akon Dahle1, Max Gr¨

  • nke2, Matt Bayliss3, Jane

Rigby4, the SGAS collaboration

March 26, 2018

1Institute of Theoretical Astrophysics, University of Oslo, Norway; 2UC Santa Barbara, California; 3MIT-Kavli, Cam-

bridge, Massachusetts; 4NASA Goddard Space Flight Center, Greenbelt, Maryland

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SLIDE 2

MegaSaura

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SLIDE 3

A spectroscopic sample of lensed starbursts at Cosmic Noon1

  • Backbone: Magellan/MagE spectra
  • Two selection effects: Lensing and rest-frame UV

brightness

  • UV Brightness makes it reasonably comparable to e.g.

(e)LARS

  • Ambition: Apples-to-apples comparison with (e)LARS,

GPs and other local samples

  • A few galaxies added to the sample afer initial

announcement, including the Sunburst

1Rigby+ 2018a,b

slide-4
SLIDE 4

A spectroscopic sample of lensed starbursts at Cosmic Noon1

  • Backbone: Magellan/MagE spectra
  • Two selection effects: Lensing and rest-frame UV

brightness

  • UV Brightness makes it reasonably comparable to e.g.

(e)LARS

  • Ambition: Apples-to-apples comparison with (e)LARS,

GPs and other local samples

  • A few galaxies added to the sample afer initial

announcement, including the Sunburst

1Rigby+ 2018a,b

slide-5
SLIDE 5

A spectroscopic sample of lensed starbursts at Cosmic Noon1

  • Backbone: Magellan/MagE spectra
  • Two selection effects: Lensing and rest-frame UV

brightness

  • UV Brightness makes it reasonably comparable to e.g.

(e)LARS

  • Ambition: Apples-to-apples comparison with (e)LARS,

GPs and other local samples

  • A few galaxies added to the sample afer initial

announcement, including the Sunburst

1Rigby+ 2018a,b

slide-6
SLIDE 6

A spectroscopic sample of lensed starbursts at Cosmic Noon1

  • Backbone: Magellan/MagE spectra
  • Two selection effects: Lensing and rest-frame UV

brightness

  • UV Brightness makes it reasonably comparable to e.g.

(e)LARS

  • Ambition: Apples-to-apples comparison with (e)LARS,

GPs and other local samples

  • A few galaxies added to the sample afer initial

announcement, including the Sunburst

1Rigby+ 2018a,b

slide-7
SLIDE 7

A spectroscopic sample of lensed starbursts at Cosmic Noon1

  • Backbone: Magellan/MagE spectra
  • Two selection effects: Lensing and rest-frame UV

brightness

  • UV Brightness makes it reasonably comparable to e.g.

(e)LARS

  • Ambition: Apples-to-apples comparison with (e)LARS,

GPs and other local samples

  • A few galaxies added to the sample afer initial

announcement, including the Sunburst

1Rigby+ 2018a,b

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SLIDE 8

Preliminary analysis: Kinematics

1500 1250 1000 750 500 250 250 500 v v0 [km/s] 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Normalized flux Accumulated absorption Line flux 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Normalized accumulated absorption v5% = 11+43

21 km/s

vint = 159+21

43 km/s

vmin = 74+21

21 km/s

v95% = 713+234

511 km/s

FWHM = 394+39

65 km/s

Example kinematic measurements: SGAS J09000+2234

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SLIDE 9

Preliminary analysis: Apparent optical depth

1500 1000 500 500 1000 Velocity [km/s] 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Normalized flux

Si II 1260 Si II 1304 Si II 1526 Si II 1808 Bin

250 500 750 1000 1250 1500 1750 fik

Bin No. 331, Velocity = -74 km/s log10N = 12.30+0.10

0.10

fC = 0.65+0.10

0.06

Example AOD fitting: SGAS J09000+2234

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SLIDE 10

First results: Strong winds, somewhat weaker absorption lines

500 750 1000 1250 1500 1750 w90% [km/s] 2 4 6 eLARS MEGaSaURA LARS 300 200 100 v50% 2 4 6 400 300 200 100 100 vSiII

50%

100 200 300 400 vLy

peak

1.0 0.5 0.0 0.5 I/I0, min 20 40 60 EWLy [Å] 400 300 200 100 v50% [km/s] 20 40 60 500 750 1000 1250 1500 1750 w90% [km/s] 20 40 60

Initial results of Megasaura and (e)LARS

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SLIDE 11

The “Sunburst Arc” PSZ1-ARC G311.6602–18.4624

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SLIDE 12

The largest and brightest known lensed galaxy

  • ∼ 1.3 Mag brighter than the nearest competitor
  • Extends over 55” on the sky
  • Likely to also intrinsically be very bright
  • Preliminary lens models suggest an extremely fortunate

alignment between lens and galaxy

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SLIDE 13

The largest and brightest known lensed galaxy

  • ∼ 1.3 Mag brighter than the nearest competitor
  • Extends over 55” on the sky
  • Likely to also intrinsically be very bright
  • Preliminary lens models suggest an extremely fortunate

alignment between lens and galaxy

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SLIDE 14

The largest and brightest known lensed galaxy

  • ∼ 1.3 Mag brighter than the nearest competitor
  • Extends over 55” on the sky
  • Likely to also intrinsically be very bright
  • Preliminary lens models suggest an extremely fortunate

alignment between lens and galaxy

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SLIDE 15

The largest and brightest known lensed galaxy

  • ∼ 1.3 Mag brighter than the nearest competitor
  • Extends over 55” on the sky
  • Likely to also intrinsically be very bright
  • Preliminary lens models suggest an extremely fortunate

alignment between lens and galaxy

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SLIDE 16

The lensing cluster was found in Planck foreground

Discovery imaging with NTT

Data from Dahle+ 2016

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SLIDE 17

The lensing cluster was found in Planck foreground

Recent observations with HST

PI: H. Dahle

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SLIDE 18

The galaxy-lens alignment is bonkers

...at least according to preliminary models.

Image: Keren Sharon, UMich

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SLIDE 19

We acquired spectra with Magellan-FIRE and MagE

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SLIDE 20

It is a typical star-forming galaxy

3500 4000 4500 5000 5500 6000 6500

  • bs [Ångström]

2 4 6 8 Flux density [erg cm

2 Hz 1 s 1]

1e 27 1200 1400 1600 1800

rest [Ångström] Si II 1190+1193 Si II 1260 O I 1302 + Si II 1304 Si IV 1393+1402 C II 1334 Si II 1526 [C III] 1907 + C III] 1909

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SLIDE 21

Similar to a local-Universe Green Pea

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SLIDE 22

The big “Wow!”: Textbook triple-peak Lyα

500 500 v vneb [km s

1]

5 10 15 20 25 30 Continuum normalized flux

PSZ1-ARC G311.6602 18.4624

Ly H

500 500 v vneb [km s

1]

Ly comparison

PSZ1-ARC G311.6602 18.4624 Cosmic Horseshoe

10 20 30

Pos 1 a 2D Ly for PSZ1-ARC G311.6602 18.4624

4080 4085 4090 4095 4100 4105 4110 4115

  • bs [Å]

10 20 30 y [pixel]

Pos 4 a

1000 500 500 1000 v vneb [km s

1]

Dahle+ 2017 (HST Midcycle proposal) Simulated profile (Behrens+ 2014)

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SLIDE 23

The big “Wow!”: Textbook triple-peak Lyα

500 500 v vneb [km s

1]

5 10 15 20 25 30 Continuum normalized flux

PSZ1-ARC G311.6602 18.4624

Ly H

500 500 v vneb [km s

1]

Ly comparison

PSZ1-ARC G311.6602 18.4624 Cosmic Horseshoe

10 20 30

Pos 1 a 2D Ly for PSZ1-ARC G311.6602 18.4624

4080 4085 4090 4095 4100 4105 4110 4115

  • bs [Å]

10 20 30 y [pixel]

Pos 4 a

1000 500 500 1000 v vneb [km s

1]

Dahle+ 2017 (HST Midcycle proposal) Simulated profile (Behrens+ 2014)

500 500 v vneb [km s

1]

5 10 15 20 Relative flux

  • Obs. Ly

Best fit

500 500 v vneb [km s

1]

  • Subt. Ly

Best fit

Lyα RT fits, with and without central peak (Rivera-Thorsen+ 2017b)

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SLIDE 24

Neutral ISM is extremely tenuous at least in a channel

5 10 15 20

Ly Scaled, smoothed H Model Ly abs.,

LyC = 1

0.0 0.5 1.0 Relative flux

Si II 1260 Si II 1526 O I 1302

1000 500 500 1000 1500 v v0 [km/s] 0.0 0.5 1.0

Si IV 1393 Si IV 1402

600 400 200 0.0 0.5 1.0 1.5

Image: Rivera-Thorsen+ 2017

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SLIDE 25

Lyman-continuum emission likely

Various LyC escape scenarios revealed in Lyα profile

  • Figure: M. Gr¨
  • nke (Rivera-Thorsen+ 2017)
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SLIDE 26

Outstanding questions

  • What are we actually looking at?

— Lens model is under development.

  • Is it leaking ionizing radiation?

— HST data scheduled for ultimo April

  • What does it look like in Lyα?

— HST narrowband observations scheduled during current cycle

  • We still don’t understand the radiative transfer.

— better modeling makes it harder to reproduce observed Lyα and LyC.

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SLIDE 27

Outstanding questions

  • What are we actually looking at?

— Lens model is under development.

  • Is it leaking ionizing radiation?

— HST data scheduled for ultimo April

  • What does it look like in Lyα?

— HST narrowband observations scheduled during current cycle

  • We still don’t understand the radiative transfer.

— better modeling makes it harder to reproduce observed Lyα and LyC.

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SLIDE 28

Outstanding questions

  • What are we actually looking at?

— Lens model is under development.

  • Is it leaking ionizing radiation?

— HST data scheduled for ultimo April

  • What does it look like in Lyα?

— HST narrowband observations scheduled during current cycle

  • We still don’t understand the radiative transfer.

— better modeling makes it harder to reproduce observed Lyα and LyC.

slide-29
SLIDE 29

Outstanding questions

  • What are we actually looking at?

— Lens model is under development.

  • Is it leaking ionizing radiation?

— HST data scheduled for ultimo April

  • What does it look like in Lyα?

— HST narrowband observations scheduled during current cycle

  • We still don’t understand the radiative transfer.

— better modeling makes it harder to reproduce observed Lyα and LyC.

slide-30
SLIDE 30