Star formation and Feedback at z>1

Alice Shapley (UCLA)

Collaborators: (UCLA) Daniel Nestor, Robin Mostardi, Kathy Kornei, Kristin Kulas, Kevin Hainline, David Law, Sarah

Nagy; (Caltech) Brian Siana, Chuck Steidel; (Carnegie) Juna Kollmeier; (UCSB) Crystal Martin; (UCSD) Alison Coil

Overview• What are the basic properties of feedback during the epoch when star-formation and AGN activity were at their peak levels?

• What are the conditions in which stars form during this epoch?

• How do these distant galaxies relate to galaxies in the local universe?(Bouwens et al. 2010)

Overview• Feedback

Outflows Radiative: escape of ionizing (Lyman-

continuum (LyC)) and Ly photons

• Physical conditions in high-redshift galaxies HII regions Metalliticies, M-Z

• AGN Demographics

• Galaxy structural properties

3 Probes of Outflows

• Understanding the processes that regulate Ly emission/absorption in high-redshift galaxies is an important goal.

• Model from Verhamme et al.: 3D Monte Carlo radiative transfer code for predicting Ly profiles given arbitrary gas density and kinematics – e.g. expanding shell.

• One particular case is that of a multiple-peaked Lyline.

Ly Probe of Outflows @ z~2-3 (Kulas, Kollmeier, Zheng, Steidel)(please see Kristin Kulas’s poster)

red blue

• Keck/NIRSPEC H/[OIII] systemic redshifts, nebular velocity dispersions, intrinsic Ly fluxes, and Ly kinematics for 18 star-forming galaxies at z~2-3 with multiple-peaked Ly emission.• Enable robust comparison with outflow models (current models don’t work!), determine outflow properties: mass outflow rates, speeds.

Ly Probe of Outflows @ z~2-3 (Kulas, Kollmeier, Zheng, Steidel)(please see Kristin Kulas’s poster)

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• Keck/LRIS Near-UV spectroscopic survey of ~200 star-forming galaxies at z=0.7-1.4 drawn from DEEP2 (FeII, MgII, CIV, MgI absorption; FeII*, MgII emission).• 72 in Extended Groth Strip region, multi-wavelength data, including HST for 56 objects.• Enables examination of outflow properties as a function of SFR, SFR, demographics.

Outflow Demographics @ z~1 (Kornei, Martin, Coil)

(please see Kathy Kornei’s poster)

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High Σ: v = -200 km/secLow Σ: v = -30 km/sec

Petrosianarea

Clumparea

• 33 Narrow-lined AGNs discovered in the course of UV-selected galaxy survey at z~2-3. Allow for host-galaxy demographic studies.• Detect not only emission lines, but also low- and high-ionization absorption lines.• SiIV absorption indicates blueshift of almost ~1000 km/s (SF galaxies have outflows of ~few hundred km/s)!• Indicates differential effect of AGN on outflowing ISM.

AGN Outflows @ z~2-3 (Hainline, Greene, Steidel)

(please talk to Kevin Hainline)

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Radiative Feedback: LyC and Ly Escape

Galaxies and the Ionizing Budget

(Bouwens et al. 2010)

• Critical questions: What are the sources that reionized the universe? What is the ionizing photon production rate from galaxies and their contribution to the global ionization rate of hydrogen?

• To answer these questions, we must chart the abundance (luminosity function) and star-formation rates of galaxies as a function of time (redshift), and estimate fesc, the escape fraction of ionizing photons from star-forming galaxies.

Measuring fesc

(Vanzella et al. 2010)

• Unfortunately, at the epoch of reionization, the Ly forest is so thick that it is impossible to determine fesc directly from z>6 (or even z>4) galaxies.

• Solution: measure fesc at z~3, relate these sources to objects at z>6.

NB Imaging of LyC emission and fesc(Nestor, Siana, Mostardi, Steidel)

(please talk to Dan Nestor and Brian Siana)

Special NB3640 filter probes right below the Lyman limit, well within one LyC mean free path. Perfect for galaxies contained in SSA22a spike at z=3.09.

Access to Keck/LRIS-B, which has unmatched sensitivity in the ~3600Å wavelength range. Most sensitive imaging instrument at this wavelength on any large telescope.

NB3640 Detections: LBG Examples

(Nestor et al. 2011)

LyC UV

NB3640 Detections: LAE Examples

(Nestor et al. 2011)

LyC Ly UV

NB3640 Detections: FUV/FLyC

(Nestor et al. 2011)

Large open symbol (LBG stack); Large filled symbol (LAE stack). Black arrows (stack of LBG and LAE non-detections).

Red crosses (stack in bins of R-mag).

• NB3640-R Probe of FUV/FLyC flux density ratio.

• Open small symbols: LBGs; Filled small symbols: LAEs.

• LBG avg.: NB3640-R=3.1 (FUV/FLyC ~11, fesc~0.1); LAE avg: NB3640-R=1.6 (FUV/FLyC

~2.2).

•NB3640-R=0 Flat spectrum in LyC vs. UV!!!!

• What are these “blue” systems?????????

• Up next: HST mapping of LyC emission (Siana). NB imaging in another field (Mostardi).

LyC

/UV

UV

Escape of Ly @ z~3(Kornei, Steidel)

(Please talk to Kathy Kornei)

• Consider Ly escape fraction, fesc,Ly

fesc,Ly = LLy,obs/LLy,int

• Measure LLy,obs. Infer LLy,int based on SFR (i.e. SFRNionLH LLy,int ).

• Average value of fesc,Ly is ~10%. Strong correlation between fesc,Ly and E(B-V).

•Suggests well mixing of dust and gas in ISM.

• Due to slit losses, must repeat analysis using Ly NB imaging.

(Kornei et al. 2010)

Physical Conditions in High-redshift galaxies

HII Regions

Rest-frame Optical Spectra• Emission-line set: [OII], H [OIII], H, [NII], [SII]

• Ratios of emission lines used to infer a wide range of physical conditions:

• Metallicity (oxygen) {R23, N2, O3N2, others}

• Electron density {[OII] and [SII] doublet ratios}

• Ionization parameter {[OIII]/[OII]}

• Electron temperature {[OIII] ratios}

• Dust extinction {Balmer line ratios}

SDSS galaxy at z=0.09

Rest-frame Optical Spectra• Emission-line set: [OII], H [OIII], H, [NII], [SII]

• At low-redshift, these emission lines form the basis of traditional optical spectroscopy.

• At z > 1.4, [OII] moves past 9000Å. Becomes a near-IR problem.

• Typically only subsets of rest-frame optical emission lines available for study. Limited information vs. SDSS spectra.

SDSS galaxy at z=0.09

WISP Survey (PI: Malkan)• Large HST pure parallel program with WFC3 G102 and G141 grisms.

• Measure SF history over last 10 billion years.

• Probe galaxy clustering on 1-2 Mpc scales.

• Constrain evolution of dust extinction and metallicity vs. luminosity and mass.

• Search for luminous z>6 Ly emitters.

• CGE team members: Nate Ross (UCLA); Brian Siana (Caltech); Alaina Henry, Crystal Martin (UCSB)

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Significant offset observed in line ratios for the lensed galaxy, The Clone and other SF galaxies at z~1-2.

• High electron densities (ne>1000 cm-3).

• High ionization parameters for these and others.

• Robust demonstration that physical conditions are different in high-redshift systems.

Near-IR Spectra of High-z Galaxies(Hainline, Coil)

(please talk to Kevin Hainline)

Future Observations

http://www.astro.ucla.edu/~irlab/mosfire/

• Keck/MOSFIRE: Multi-Object Spectrometer for Infra-Red Exploration; co-Pis: McLean (UCLA) and Steidel (Caltech)

• Near-IR (0.9-2.5 m) spectroscopy over 6.1’ ✕ 6.1’ FOV, one band (YJHK) at a time, multiplex advantage up to 46 slits using robotic, cryogenic configurable slit unit. R=2300-3300 with 0.7” slit .

• Pre-ship review on April 11th.

(To learn more, please talk to Kristin Kulas)

Future Plans: M-Z w/ MOSFIRE

• The M-Z relation may yield fundamental clues about the nature of feedback and winds in star-forming galaxies.

• Only a handful of individual galaxies at z>1 have metallicity measurements.

• With MOSFIRE, we can do a definitive survey of the M-Z relation at high redshift (and dust extinction and SFR and physical conditions).

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AGN Demographics

Future Plans: M-Z w/ MOSFIRE

• AGN host galaxies at z~2-3 appear to be older, more mature than average. What is the timing of AGN activity?

• Stellar population and rest-frame optical emission-line properties of AGNs.

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(Hainline, Greene)(please talk to Kevin Hainline)

Galaxy Structural Parameters

Galaxy Morphology at z~1.5-3.0

• WFC3/IR F160W imaging for ~300 z~1.5-3.0 UV-selected galaxies.

• Measurement of galaxy structural parameters, connection with feedback parameters.

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(Law, Nagy, Steidel)(please talk to David Law)

Galaxy Morphology at z~1.5-3.0

• Measure mass-radius relation at z~1.5-3.0.

• Demonstrate evolution: smaller radius at fixed stellar mass, consistent with (1+z)-1.

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(Law, Nagy, Steidel)(please talk to David Law)

Closing remarks• Lots going on at UCLA in the study of the high-redshift universe!

• We are actively trying to understand feedback processes and the nature of star formation at high redshift.

• Eager to interact with theorists about: outflow properties, sources of ionizing photons, connections between galaxies and dark matter halo hosts.

• Eager to make plans for a ground-breaking survey of z>1 star-forming regions (metallicity, dust extinction, etc.) with MOSFIRE.

• Come visit UCLA, give a talk at our extragalactic reading group!