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, 2018 1 Institute of Theoretical Astrophysics, University of Oslo, Norway; 2 UC Santa Barbara, California; 3 MIT-Kavli, Cam- bridge, Massachusetts; 4 NASA Goddard Space Flight Center, Greenbelt, Maryland
M eg aSa ura
A spectroscopic s ample of lensed starbursts at Cosmic Noon 1 • 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 1 Rigby+ 2018a,b
A spectroscopic s ample of lensed starbursts at Cosmic Noon 1 • 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 1 Rigby+ 2018a,b
A spectroscopic s ample of lensed starbursts at Cosmic Noon 1 • 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 1 Rigby+ 2018a,b
A spectroscopic s ample of lensed starbursts at Cosmic Noon 1 • 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 1 Rigby+ 2018a,b
A spectroscopic s ample of lensed starbursts at Cosmic Noon 1 • 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 1 Rigby+ 2018a,b
P reliminary analysis: Kinematics 1.4 1.4 Accumulated absorption Line flux 1.2 1.2 Normalized accumulated absorption 1.0 1.0 0.8 0.8 Normalized flux 0.6 0.6 0.4 0.4 v 5% = 11 +43 21 km/s 0.2 0.2 v int = 159 +21 43 km/s v min = 74 +21 21 km/s 0.0 v 95% = 713 +234 511 km/s 0.0 FWHM = 394 +39 65 km/s 0.2 0.2 1500 1250 1000 750 500 250 0 250 500 v 0 [km/s] v Example kinematic measurements: SGAS J09000+2234
P reliminary analysis: Apparent optical depth 1.4 Bin No. 331, Velocity = -74 km/s 1.2 log 10 N = 12.30 +0.10 0.10 f C = 0.65 +0.10 0.06 1.0 Normalized flux 0.8 0.6 0.4 Si II 1260 0.2 Si II 1304 Si II 1526 Si II 1808 0.0 Bin 1500 1000 500 0 500 1000 0 250 500 750 1000 1250 1500 1750 Velocity [km/s] f ik Example AOD fitting: SGAS J09000+2234
F irst results: Strong winds, so mewhat weaker absorption lines 6 6 eLARS 400 MEGaSaURA LARS 4 4 300 peak v Ly 200 2 2 100 0 0 500 750 1000 1250 1500 1750 300 200 100 0 400 300 200 100 0 100 w 90% [km/s] v 50% v SiII 50% 60 60 60 EW Ly [Å] 40 40 40 20 20 20 0 0 0 1.0 0.5 0.0 0.5 400 300 200 100 0 500 750 1000 1250 1500 1750 I / I 0, min v 50% [km/s] w 90% [km/s] Initial results of Megasaura and (e)LARS
The “Sunburst Arc” PSZ1-ARC G311.6602–18.4624
T he 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
T he 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
T he 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
T he 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
T he lensing cluster was found in Planck foreground Discovery imaging with NTT Data from Dahle+ 2016
T he lensing cluster was found in Planck foreground Recent observations with HST PI: H. Dahle
T he galaxy-lens alignment is bonkers ...at least according to preliminary models. Image: Keren Sharon, UMich
We acquired spectra with Magellan-FIRE and MagE
It is a typical star-forming galaxy Flux density [erg cm 2 Hz 1 s 1 ] 0 2 4 6 8 1e 3500 27 4000 Si II 1190+1193 1200 Si II 1260 O I 1302 + Si II 1304 4500 C II 1334 1400 Si IV 1393+1402 rest [Ångström] obs [Ångström] 5000 Si II 1526 1600 5500 6000 1800 [C III] 1907 + C III] 1909 6500
Similar to a local-Universe Green Pea
T he big “Wow!”: Textbook triple -peak Ly α PSZ1-ARC G311.6602 18.4624 Ly comparison 30 Ly PSZ1-ARC G311.6602 18.4624 Continuum normalized flux H Cosmic Horseshoe 25 20 15 10 5 0 500 0 500 500 0 500 Simulated profile (Behrens+ 2014) v v neb [km s 1 ] v v neb [km s 1 ] 2D Ly for PSZ1-ARC G311.6602 18.4624 v v neb [km s 1 ] 1000 500 0 500 1000 Pos 1 a 30 20 10 y [pixel] 0 Pos 4 a 30 20 10 0 4080 4085 4090 4095 4100 4105 4110 4115 obs [Å] Dahle+ 2017 (HST Midcycle proposal)
T he big “Wow!”: Textbook triple -peak Ly α PSZ1-ARC G311.6602 18.4624 Ly comparison 30 Ly PSZ1-ARC G311.6602 18.4624 Continuum normalized flux H Cosmic Horseshoe 25 20 15 10 5 0 500 0 500 500 0 500 Simulated profile (Behrens+ 2014) v v neb [km s 1 ] v v neb [km s 1 ] 2D Ly for PSZ1-ARC G311.6602 18.4624 v v neb [km s 1 ] 1000 500 0 500 1000 Pos 1 a Obs. Ly Subt. Ly 30 20 Best fit Best fit Relative flux 20 15 10 10 y [pixel] 0 5 Pos 4 a 30 0 500 0 500 500 0 500 20 v v neb [km s 1 ] v v neb [km s 1 ] 10 0 Ly α RT fits, with and without central peak 4080 4085 4090 4095 4100 4105 4110 4115 obs [Å] (Rivera-Thorsen+ 2017b) Dahle+ 2017 (HST Midcycle proposal)
Neutral ISM is extremely tenuous at least in a channel Ly 1.5 20 Scaled, smoothed H 1.0 Model Ly abs., LyC = 1 15 0.5 0.0 600 400 200 10 5 0 Relative flux 1.0 0.5 Si II 1260 Si II 1526 O I 1302 0.0 1.0 0.5 Si IV 1393 Si IV 1402 0.0 1000 500 0 500 1000 1500 v 0 [km/s] v Image: Rivera-Thorsen+ 2017
L y man-continuum emission likely Various LyC escape scenarios revealed in Ly α profile ��������������� ������������ ���������������� Figure: M. Gr¨ onke (Rivera-Thorsen+ 2017)
Outst anding 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 Ly α ? — HST narrowband observations scheduled during current cycle • We still don’t understand the radiative transfer. — better modeling makes it harder to reproduce observed Ly α and LyC.
Outst anding 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 Ly α ? — HST narrowband observations scheduled during current cycle • We still don’t understand the radiative transfer. — better modeling makes it harder to reproduce observed Ly α and LyC.
Outst anding 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 Ly α ? — HST narrowband observations scheduled during current cycle • We still don’t understand the radiative transfer. — better modeling makes it harder to reproduce observed Ly α and LyC.
Outst anding 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 Ly α ? — HST narrowband observations scheduled during current cycle • We still don’t understand the radiative transfer. — better modeling makes it harder to reproduce observed Ly α and LyC.
Recommend
More recommend
