Strong Lensing with Euclid and SKA The future of strong lensing with 100,000+ lenses

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1 Strong Lensing with Euclid and SKA The future of strong lensing with 100,000+ lenses Léon Koopmans (Kapteyn Astronomical Institute) Vegetti et al. McKean et al. Euclid-SKA Synergy - Oxford, Sept

2 Strong Lensing in the era of Euclid/SKA? Unique lensing studies, now and in the future. Galaxy structure and evolution as function of mass, redshift and type: Dark-matter & Stellar mass profiles/shapes, IMF What is the normalization and shape of the (CDM) mass function and how does it evolve as function of redshift (DM physics) dlogn/dlogm = -2 (CDM)? Over what mass range? Or W/SIDM? Geometric measures of the mass and properties of galaxy stellar cores and SMBHs over cosmic time Do SMBHs (or M-sigma relation) evolve with cosmic time Do higher-z galaxies show any/more binary BHs? Tests of gravity on large (Universe) and small scales (BH shadows)

3 Galaxy Structure & Evolution Chabrier Salpeter Total Density Profile DM Density Profile Stellar/DM Mass Fractions Stellar IMF Kinematic Structure

4 A glimpse of the future: Quantitative (CDM) Substructure massfunction studies Science Goals: The level of virialised (CDM) mass substructure/satellites Quantifying the mass/mass-tolight of luminous satellites Quantifying the power-spectrum of mass structure in galaxies Assess nature of dark matter As function of redshift, galaxy mass, type, etc. Courtesy: Vegetti

5 (CDM) Substructure Keck LGS-AO K-band observations B : L* galaxy at z=0.881, zs=2.5 Grid-base modeling (Vegetti & Koopmans 2009) Lagattuta et al. 2012; Vegetti et al., 2012, Nature

6 (CDM) Substructure Keck LGS-AO H-band B Both Keck-LGS AO H-band and HST F160W band (from 1999!) data confirm this detection. Detection of a compact dark-matter dominated object with M=1.7x10 8 Msun Vegetti et al. 2012, Nature HST F160W band NICMOS data is comparable to Euclid VIS

7 GL constraints on the CDM mass-function W/O slope prior With slope prior Results are at the upper range of CDM simulations, but the analysis of more systems is underway and improvements in the analysis if the results might shift this (also LOS contribution might lower the fraction by a factor of up to a few). Slope: = =1.9 ( CDM) Mass fraction: dn dm / f CDM m f sub = Xu et al Vegetti et al. 2012, Nature

8 10 lenses (CDM) Substructure Already ~200 lenses of HST-like quality from Euclid and/or SKA allow one to place very precise limits on the level of mass substructure in lens-galaxies in the mass range <10 9 Msun More systems allow this to be determined as function of redshift, mass and galaxy-type. Vegetti & Koopmans (2009) 200 lenses

9 Implications? Tilt of the substructure mass function e.g. Warm Dark Matter Cutoff/suppression of the DM power-spectrum Range of current two detections Cutoff of the substructure mass function Dunstan et al. 2011

10 What number of strong gravitational lenses do we want/need in 2020+? Simple statistics and the curse of higher dimensions. If we want to study galaxies over a wide range of parameters, we need MANY galaxies even for a small # of galaxies per N-dim voxel. Goal (1): Say 1% error on mass slopes (γ ). Currently dominated by intrinsic scatter (7%) so we require 50+ lenses per parameter-voxel (e.g. Barnabe et al. 2011) Goal (2): Say 0.1% error in the mass fraction in substructure (<1% predicted) needs a similar number on lens system with extended images (Vegetti & Koopmans 2009; Vegetti et al. 2012; Vegetti et al. 2013) If we also want to study this as function of mass, environment and cosmic time: (a) 10 bins of 1 (or variable) Gyr cosmic time, (b) 10 bin in mass (say 0.3/variable dex from solar mass) (c) split over 3 types: spiral, lenticular, elliptical (d) split over 4 environments: void, field, group & cluster This requires 10 (4-5) lenses to beat sample variance, noise & biases to a level of present day state-of-the-art galaxy studies (e.g. CANDLES, COSMOS, 2dF, SDSS, DEEP, etc.)

11 What else is needed to make strong lenses even more useful in 2020+? NUMERICALLY: 100,000+ strong lenses spread over redshift (z=0-3) probing a wide range of masses, environments and galaxy types. SPATIALLY: High-res follow-up: Detailed studies of the lens mass distribution (substructure, flux-ratio anomalies, etc) and sources with ground-based 30-40m telescope AO telescopes, space-based instruments, (sub)-mm arrays and with long-baseline radio telescopes (<<1 ). SPECTRALLY: Broad-band colors: One frequency is not enough. SED of lens and source studies (from radio to UV and beyond) for IMF, M/L and other studies. Crude photo-z s. SPECTRALLY: Higher-R Spectra: To maximize science return, most if not all systems (source and lens) need redshifts to set the galaxy mass and luminosity (a lesson from CLASS vs SLACS!). Also IMF, M/L, and kinematic studies. dν/ν ~ 100s s, or more. TEMPORALLY Monitoring: Time-delays for cosmography, source studies, substructure, etc...

12 Euclid & SKA Similar and complementary Similar near-full sky coverage: ~2π sr Similar angular resolution: ~0.2 FWHM Similar number density of sources: ~ per sq. degree Complementary wavebands: Radio/NIR NIR: Lenses are bright/most sources are faint Radio: Sources are bright/most lenses are faint(?) Redshifts from spec/photo-z (Euclid) and HI (SKA) Allows cross-correlation Cross-correlations of lens galaxies/sources Most lens galaxies at z<1, most radio sources at z>1

13 Synergy between SKA and Euclid and other telescopes SKA & Euclid Cross-correlation of SKA with Euclid images will reduce confusion Many SKA lenses might not show the lens galaxy. Euclid will provide this with high-res VIS and low-res NIR images, photo-z s and possibly spectroscopy Some Euclid lens-galaxies will be active AGN in the radio Neutral HI could be used to get redshifts in lenses/sources using SKA LSST/PANSTARRS (2018+) - colors, variability monitoring JWST (2018+) - deep high-res imaging, spectroscopy, high-z source, kinematics ELT/TMT,... - AO assisted imaging and spectroscopy, kinematics, ALMA - molecular imaging of the source/lens (kinematics?)... Weak lensing from Euclid can be done around (SKA) lenses.

14 Euclid

15 Euclid Strong-Lensing Science Working Group Ben Metcalf, Carlo Giocoli, Eric Jullo, Fabio Bellagamba, Gregor Seidel, Hakim Atek, Jean-Luc Starck, Jean-Paul kneib, Leon Koopmans, Leonidas Moustakas, marc gentile, Massimo Meneghetti, Neal Jackson, Phil Marshall, Raphael Gavazzi, Rémi Cabanac, Sami Niemi, Sandrine Pires, Stephen Serjeant, Steven Kahn The goal of this OU-SHE Work Package is to generate samples of strongly lensed sources at all spatial scales, from individual galaxies to galaxy clusters. The main objectives and tasks are to: study of the spatial distribution of dark matter at all scales constrain the cosmological parameters (lens counts, lensing tomography) study galaxy structure and evolution provide a tool to study distant sources (natural telescope) use lensed sources (e.g. QSOs) as probe of the ISM/IGM between source and observer find "exotic lenses" (multiple lensed sources at different redshifts, cosmic strings, unexpected lensing configurations)

16 SL Expectations from Euclid Three main classes of lenses: Individual (massive) galaxies Galaxies in groups/clusters (environment!) Massive galaxy clusters Cosmic strings? General Predictions: Galaxies lensed by galaxies: ~10 per square degree, or ~10 5 over the 15k sq.deg. (e.g. Pawase et al. 2012) QSOs lensed by galaxies: ~10 3 Clusters/groups with giant arcs: ~0.5 per square degree, or ~10 4 over 20k sq.deg (based on SL2S) Clusters with many multiple images: ~10 2 (the most massive clusters MACS type) Euclid simulation by Meneghetti

17 SL Expectations from Euclid Galaxy-scale simulations (Lead: B. Metcalf) 1. Explore more source sizes and positions and include QSOs+host as sources 2. Give catalogues for lens and source parameters (also for grism simulations) 3. Add Euclid YJH filters and groundbased data (KIDS-like) and ugrizyjhk filters (same shape for all sources) 4. Keep sources simple (analytic) but use realistic (HST) lenses 5. Provide stamps with a- actual lenses, b- non-lenses 6. Provide large fields of view, in addition to the stamps 7. Start simulations for grism: provide separate images of sources and lenses with no noise, no PSF and for the VIS pixel size Euclid simulations by Metcalf

18 SL Expectations from Euclid Galaxy-scale simulations (Lead: B. Metcalf) 1. Explore more source sizes and positions and include QSOs+host as sources 2. Give catalogues for lens and source parameters (also for grism simulations) 3. Add Euclid YJH filters and groundbased data (KIDS-like) and ugrizyjhk filters (same shape for all sources) 4. Keep sources simple (analytic) but use realistic (HST) lenses 5. Provide stamps with a- actual lenses, b- non-lenses 6. Provide large fields of view, in addition to the stamps 7. Start simulations for grism: provide separate images of sources and lenses with no noise, no PSF and for the VIS pixel size Euclid simulations by Metcalf

19 SL Expectations from Euclid RIZ J Y H Cluster-scale simulations (Lead: M. Meneghetti) 1. Produce realistic clusters (Frontier fields) to test massmaps and magnification-map reconstructions 2. Put the simulated clusters in Millenium cones 3. Include images of lensed sources without noise in the outputs 4. Produce IR Euclid data Euclid simulations by Meneghetti

20 SL Expectations from Euclid RIZ J Y H Cluster-scale simulations (Lead: M. Meneghetti) 1. Produce realistic clusters (Frontier fields) to test massmaps and magnification-map reconstructions 2. Put the simulated clusters in Millenium cones 3. Include images of lensed sources without noise in the outputs 4. Produce IR Euclid data Euclid simulations by Meneghetti

21 SL Expectations from Euclid RIZ J Y H Euclid simulations by Meneghetti Cluster-scale simulations (Lead: M. Meneghetti) 1. Produce realistic clusters (Frontier fields) to test massmaps and magnification-map reconstructions 2. Put the simulated clusters in Millenium cones 3. Include images of lensed sources without noise in the outputs 4. Produce IR Euclid data

22 From curiosity to a multi-purpose tool for unique galaxy structure & formation studies SLACS (2010)

23 From curiosity to a multi-purpose tool for unique galaxy structure & formation studies Euclid SLACS (2020) (2010)

24 From curiosity to a multi-purpose tool for unique galaxy structure & formation studies Euclid SLACS (2020) (2010) Euclid (2020+)

25 Square Kilometre Array

26 Science with SKA Strong Lenses Galaxy structure and formation (DM + baryons) (CDM) Substructure and non-linear mass function SMBHs in the centers of galaxies (SKA-VLBI) Weak + strong lensing to get their outer haloes Cosmography (double, triple(?) lens-plane systems) Measuring time-delays for cosmography (H0), substructure, etc Rare and exotic lensing events Tests of gravity (PPN, BH shadow?) Micro- and milli-lensing with VLBI-level resolution (μas/mas) Lens galaxy (ionized) ISM through multi-frequency scattering Resolving high-z radio source structure through high-μ lensing Incomplete and possibly biased science cases

27 A straw man's lens survey RASKALS ( Radio All-SKA Lens Survey ) (Koopmans et al. 2004) What do we get from an all-sky 1.4GHz SKA survey with ~0.4 resolution and down ~few μjy sensitivity? Similar to SKA1-mid continuum survey (R. Braun) for the current baseline design.

28 Expectations SKA sources Some rough numbers at S1.4GHz>10μJy Redshift AGN SFG C. Jackson et al Source counts are around 10 4 radio sources per square degree ~10 4 SF galaxies + AGN per square degree in a dex of flux-density around 20 mujy. (Jackson et al.) The dominant population is SF galaxies (~85%), AGN (~15%). Most (2/3) of SF sources are beyond z=1, 50% between z=1-2 and 5-10% at z=3-5, very few beyond z=5.

29 Requirements for RASKALS SKA2 (8% in SKA1) A e /T = 12, 000 m 2 K 1 S 1.4GHz 1 p BGHz t min µjy 100 km array (SKA memo 114; Condon. ) Confusion noise at 1.4GHz with 0.4 FWHM beam is still only at 0.2 μjy and can still be neglected A half-sky survey down to ~1 μjy. It takes 4 min with SKA1/2 to get down to 1 μjy at 3/10- sigma (RASKAL1/2) for B=0.25GHz. Very similar to SKA1-mid continuum survey (R. Braun) for the current baseline design for a wider bandwidth. FoV = 1.0 deg 2 (single or multi-beaming): 2 month full-time imaging, 4 min per pointing (or ~1 yr for 4hr/day). Resolution of ~0.4 (CLASS): ~100 km 1.4GHz

30 Browne et al. 2003, Myers et al RASKALS: Lensed QSRs What would they look like? QSO lenses would look a lot like CLASS lenses with similar resolution (at 1.4GHz) and similar S/N ratio (most lenses are near the flux-limit). Extended AGN and SF galaxies will form arcs and Einstein rings. MG & PKS lenses

31 Expectations SKA lenses (high-z lenses and sources) dp/dlog10(z) The probability that a z=3-5 source is lensed is around P = (incl. magnification bias). The number of sources above 10 μjy between z=3-5 is ~600 per sq. deg.. The expectation value per sq.d. is ~1 lensed source at zs=3-5 with a lens redshift most likely between zl= zs=3.0 zs=4.0 zs= zs=2.0 zs= Redshift lens

32 Expectations SKA lenses In conclusion: RASKAL1/2 could be carried out in 2 months full time with an SKA1/2 with A/T=1200/12,000 (A=0.1/1 km 2, Tsys = 80K) for an array of 100 km (FWHM beam = 0.4 ) at ν=1.4 GHz. Above S1.4GHz =10 μjy, we expect: 2x10 8 sources (85% SFG, 15% 3/10-σ detection of these ~60,000 lenses with lensed SFGs at zs=1-3 ~20,000 lenses with lensed SFGs at zs=3-5 ~10,000 lenses with lensed QSRs at z~2 (CLASS rate of 1:600 suggests 3x more lenses, so we are conservative; assumed magnification bias might be too low). Total: ~10 5 lensed objects in RASKALS: most are extended SFGs/QSRs

33 Lenses can be followed up at ~10 mas resolution w/ska2: Substructure? EVN result on B Beam size (psf): 5 x 3 milli-arcsec rms: 59 ujy / beam uniform weighting Global VLBI (European VLBI Network, Very Long Baseline Array (US) and Green Bank Telescope; 19 telescopes in total) 14 Hours on source GHz (this is 1/8 of the total bandwidth). Credit: J. McKean

34 Lenses can be followed up at ~10 mas resolution w/ska2: Substructure? EVN result on B Credit: McKean Beam size (psf): 5 x 3 milli-arcsec rms: 59 ujy / beam uniform weighting Global VLBI (European VLBI Network, Very Long Baseline Array (US) and Green Bank Telescope; 19 telescopes in total) 14 Hours on source GHz (this is 1/8 of the total bandwidth). Credit: J. McKean European VLBI Network: 10% of SKA on long baselines

35 Conclusions The future is bright for strong lensing in 2020+, especially in the era of Euclid and SKA. SL remains competitive even unique in many research areas: non-linear structure evolution (galaxy-group-cluster), CDM substructure, SMBH lensing, etc. We can expect >10 5 strong lenses from Euclid/SKA, many with redshifts for the lens/ source and high-resolution images. SKA and Euclid combined prevent most follow-up! Do we need to worry? - How do we find all these lenses in billions of objects (confusion/biases)? - Incompleteness and not all lenses/sources might have good redshifts or follow-up. - How is further follow-up done with (relatively inefficient) small-fov large telescopes such as JWST, ELT/TMT or even ALMA? Although the preparation for this avalanche of lenses and their follow-up is not yet done and many issues are not resolved, exciting times are indeed ahead!