What lensed galaxies can tell us about winds, hot stars, and physical conditions

Transcription

1 What lensed galaxies can tell us about winds, hot stars, and physical conditions! z=2.161 z=3.066 Jane Rigby!! JWST Deputy Project Scientist for Operations! NASA Goddard Space Flight Center! I ll talk about how spectroscopy of gravitationally lensed galaxies advances the goal of this meeting to use emission line diagnostics to understand galaxies and their evoln. I ll start by illustrating the power of this technique.

2 Redshift 1-2 galaxies as seen by Hubble RCS0327 ijh 3.4 z=1.70 S. Wuyts et al. 2013, CANDELS + 3D-HST The HST λ/d diffraction limit for Hα at z=1.5 is 0.14, or 1.1 kpc.

3 RCS0327 ijh z=1.70 F390, 814, 160 Our C19 program (PI Rigby).

4 RCS0327 ijh z=1.70 F390, 814, 160 Sharon, Gladders, Rigby, Wuyts et al Our C19 program (PI Rigby).

5 RCS0327 ijh z=1.70 F390, 814, kpc = 1 Sharon, Gladders, Rigby, Wuyts et al Our C19 program (PI Rigby).

6 The brightest lensed galaxy: RCS0327 at z=1.70. Sharon, Gladders, Rigby, Wuyts et al. 2012!!

7 The brightest lensed galaxy: RCS0327 at z=1.70. Sharon, Gladders, Rigby, Wuyts et al. 2012!!

8 Rest-UV diagnostic spectroscopy of galaxies cb58 Cosmic Eye, Cosmic z~3 composite z>3 composite Pettini et al. 2000, 2002 Quider et al. 2009, 2010 Shapley et al Jones et al BX418 (low-z) Erb et al Shapley et al. 2003; Jones et al 2012 cb58: Pettini et al. 2000

9 MagE/Magellan rest-uv spectra of lensed galaxies SGAS 1527 z=2.76 SGAS 0957, z=1.821 SGAS 1221, z=2.93 MagE/Magellan spectra: R=2000, A 13 lensed galaxies; 8 have SNR>10 per-pixel ~120 hr total integration Targets from SDSS Giant Arcs Survey (SGAS) Time through Carnegie, U. Chicago, U. Michigan, CfA 2 galaxies have spectra of multiple regions

10 MagE/Magellan rest-uv spectra of lensed galaxies Here are some of the spectra, for lensed galaxies at redshifts of 2.9, 2.0, 1.68

11 C IV and He II 1640 as hot star diagnostics EW(He II 1640) emission absorption Brinchmann et al. 2008; pt is Shapley et al EW(CIV) Eldridge & Stanway 2012 Introduce He II 1640 emission and CIV emission and wind absorption as two metrics of hot star populations. Pioneered for distant populations by Pettini et al and 2002.

12 C IV and He II 1640 as hot star diagnostics EW(He II 1640) emission absorption Brinchmann et al. 2008; pt is Shapley et al Rigby et al. in prep. EW(CIV) Eldridge & Stanway 2012 Introduce He II 1640 emission and CIV emission and wind absorption as two metrics of hot star populations. Pioneered for distant populations by Pettini et al and 2002.

13 C IV and He II 1640 as hot star diagnostics Eldridge & Stanway 2012 & Pettini et al Rigby et al. in prep. E&S 2012 analyzed spectra of five LGBs, plus Shapley composite. 4 were lensed. Want to extend this analysis to 8 more galaxies from the MagE lensed sample. Z from rest-optical. Are the theoretical models doing justice to the quality of the obs. data?

14 C IV and He II 1640 as hot star diagnostics 8.5 kpc = 1 Rigby et al. in prep.

15 C IV and He II 1640 as hot star diagnostics 8.5 kpc = 1 Rigby et al. in prep.

16 C IV and He II 1640 as hot star diagnostics z=3.62, two spatial positions. Bayliss et al (IAU proc) More spatial variation in CIV line strength along lensed arc. z=3.62

17 C III] 1907, 1909 emission Stark et al. z~2 Rigby et al. in prep. Bayliss et al z=3.6 Leitherer et al. 2011, Pena-Guerrero et al. in prep. Rigby et al. in prep. Dan Stark will discuss this diagnostic later in the workshop. For now, want to note that our sample has detected C III], but far more modest EWs. Not extreme emitters like in Stark sample. Also want to add to the conversation that strong C III] emitters do exist in the z=0 universe. Writing this up now. Metallicity can t be the only variable at work.

18 Two hours on Gemini. SGAS , arc z= Bayliss, Rigby et al Nebular abundance ratios: C, N, O, Si. We pathfound this in Rigby+2011 at z=1.70 using rest-optical lines. Pathfound in Bayliss+2014 using rest-uv lines, in a z=3.62 galaxy. Will do this for the whole MagE sample, using the rest-uv intercombinational lines. Supported with metallicities from NIRSPEC on Keck and FIRE on Magellan.! Other interesting items: Strong He II emission and CIV emission. Pretty strong C III], but damped Lya. P Cygni features are strong and narrow, not well fit by S99. Others have pointed this out too need better hot star models!

19 Two hours on Gemini. SGAS , arc z= Bayliss, Rigby et al Starburst99, 2Myr burst Nebular abundance ratios: C, N, O, Si. We pathfound this in Rigby+2011 at z=1.70 using rest-optical lines. Pathfound in Bayliss+2014 using rest-uv lines, in a z=3.62 galaxy. Will do this for the whole MagE sample, using the rest-uv intercombinational lines. Supported with metallicities from NIRSPEC on Keck and FIRE on Magellan.! Other interesting items: Strong He II emission and CIV emission. Pretty strong C III], but damped Lya. P Cygni features are strong and narrow, not well fit by S99. Others have pointed this out too need better hot star models!

20 Mg II 2796, 2803 emission Mg II emission common in z>1 star-forming galaxies, but rare at z=0. (e.g. Weiner et al. 2009; Rubin et al. 2010, 2011; Giavalisco et al. 2011; Prochaska et al. 2011; Erb et al )! Resonant line, like Lyman alpha. Does it trace Lyman alpha? No. Rigby, Bayliss et al Mg II flux density Mg II Ly a velocity Two slides on MgII: one on R14, one on Bordoloi in prep.

21 Mg II 2796, 2803 emission Knot-to-knot variation in RCS kpc = 1 Winds vary from knot-to-knot, in flux, velocity. Locally sourced?

22 Mg II 2796, 2803 emission 8.5 kpc = 1 Bordoloi, Rigby et al. in prep. Knot-to-knot variation in RCS0327. Winds vary from knot-to-knot, in flux, velocity. Locally sourced?

23 Mg II 2796, 2803 emission Mg II Fe II Bordoloi, Rigby et al. in prep. MgII Bordoloi paper. Have spectra for four knots. Fitting outflow, systemic, and inflow gas.

24 Mg II 2796, 2803 emission Bordoloi, Rigby et al. in prep. Outflow velocity is correlated w the star formation rate surface density. Trend is 2.5 sig significant at mean absorption, gets more pronounced for the higher percentile gas. MgII is spatially extended, so can estimate mass outflow rates and loading factors. They are high!

25 Mg II 2796, 2803 emission Bordoloi, Rigby et al. in prep. Outflow velocity is correlated w the star formation rate surface density. Trend is 2.5 sig significant at mean absorption, gets more pronounced for the higher percentile gas. MgII is spatially extended, so can estimate mass outflow rates and loading factors. They are high!

26 Rest-optical spectroscopy: mass-metallicity relation Wuyts, Rigby, Gladders et al. 2012b Switch gears to rest-frame optical diagnostics. Just mention the mass-metallicity relation, that lensed galaxies give unique constraints at the low stellar mass end. Complementary to Keck surveys like KBSS, MOSDEF

27 Rest-optical spectroscopy: physical conditions ne = cm- 3 logu = Te = K 12 + log(o/h) > [N/O] = [Ne/O] = [Ar/O] = Rigby, Wuyts, Gladders et al Measure physical conditions to very high precision. 50,000 counts at H beta! (poisson SNR=200). Log U is NOT elevated. Multiple diagnostics of metallicity tests of bright line diagnostics. Elevated in BPT diagram, but NOT due to nuclear activity. (Av = 0.7) (See also Erb et al. 2010; Stark et al. 2014)

28 Rest-optical spectroscopy 8.5 kpc = 1 Keck OSIRIS Wuyts, Rigby, Gladders, & Sharon 2014 Keck OSIRIS IFU spectroscopy reveals that this is an ongoing interaction, a merger. Evidence: velocity structure of tidal tail, and the structure of the velocity dispersion.

29 Rest-optical spectroscopy 8.5 kpc = 1 Keck OSIRIS Wuyts, Rigby, Gladders, & Sharon 2014 Further, this is an interaction between two equal mass galaxies, each M* ~3x10^9 Msol. 1st galaxy is forming stars; 2nd galaxy is not forming stars, stands from old stellar population in WFC3 F160W and Spitzer IRAC. Could have not gotten this quality IFU spectroscopy if not lensed.

30 Rest-optical spectroscopy: physical conditions Last set of diagnostics I want to talk about are from WFC3 grisms. 4 orbits of WFC3 grism data in Cycle 19! Mention Gabe Brammer, and NPP fellow Kate Whitaker. Whitaker, Rigby, et al. 2014

31 Rest-optical spectroscopy: physical conditions Last set of diagnostics I want to talk about are from WFC3 grisms. 4 orbits of WFC3 grism data in Cycle 19! Mention Gabe Brammer, and NPP fellow Kate Whitaker. Whitaker, Rigby, et al. 2014

32 Rest-optical spectroscopy: physical conditions Spatial variation of extinction, via Hβ/Hɣ Sensitive to variation in extinction on kpc scales. In this case, uniform dust across the merger. Whitaker, Rigby, et al. 2014

33 Rest-optical spectroscopy: physical conditions Stellar mass function, via He I 5876 / Hβ λ (A ) Whitaker, Rigby, et al. 2014

34 Rest-optical spectroscopy: physical conditions Stellar mass function, via He I 5876 / Hβ λ (A ) Whitaker, Rigby, et al. 2014

35 Rest-optical spectroscopy: physical conditions Stellar mass function, via He I 5876 / Hβ λ (A ) Whitaker, Rigby, et al. 2014; Rigby & Rieke 2004 Very simple physics! Ratio of He I to Hbeta or Halpha is the relative sizes of the Helium and Hydrogen Stromgren spheres. Tells you about the most massive stars in 1.3<z<2.3 galaxies Our calcs: WFIRST HLS will detect HeI in the brightest knot of He I in RCS0327.

36 New program in HST Cycle orbit program in HST C23 (PI Rigby) Two targets at z=1.329 and z=1.420 G102 + G141 grism Every emission line diagnostic from [O II] 3727 to [S II] 6731 Diagnostics of SFR, logu, Z, E(B-V), spectral hardness, shocks Inspired by our C19 program, and Tucker Jones s work in GLASS. Sweet spot of redshift for grisms: z=1.4 The full diagnostic suite, at ultimate spatial resolution and SNR. Spatially resolved physical conditions. Test of photoionization models. Tests assumptions we have to make for large surveys of field galaxies.

37 Closing words We obtain spectra of gravitationally lensed galaxies to overcome the limits of current telescopes: detect faint diagnostics obtain much higher signal-to-noise, resolve much smaller physical regions (down to 100pc).! The tradeoffs are: smaller sample sizes must contextualize with field galaxies. λ (A )