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?
(Bouwens et al. 2010)
• How do these distant galaxies
relate to galaxies in the local
universe?
Overview
•
Feedback
 Outflows
 Radiative: escape of ionizing (Lymancontinuum (LyC)) and Lya photons
• Physical conditions in high-redshift galaxies
 HII regions
 Metalliticies, M-Z
•
AGN Demographics
•
Galaxy structural properties
3 Probes of Outflows
Lya Probe of Outflows @ z~2-3
red
(Kulas, Kollmeier, Zheng, Steidel)
(please see Kristin Kulas’s poster)
blue
• Understanding the processes that regulate Lya emission/absorption in high-redshift
galaxies is an important goal.
• Model from Verhamme et al.: 3D Monte Carlo radiative transfer code for predicting
Lya profiles given arbitrary gas density and kinematics – e.g. expanding shell.
• One particular case is that of a multiple-peaked Lya line.
Lya Probe of Outflows @ z~2-3
(Kulas et al. 2011)
(Kulas, Kollmeier, Zheng, Steidel)
(please see Kristin Kulas’s poster)
• Keck/NIRSPEC Ha/[OIII] systemic redshifts, nebular velocity dispersions, intrinsic
Lya fluxes, and Lya kinematics for 18 star-forming galaxies at z~2-3 with multiplepeaked Lya emission.
• Enable robust comparison with outflow models (current models don’t work!),
determine outflow properties: mass outflow rates, speeds.
Outflow Demographics @ z~1
(Kornei et al. 2011)
(Kornei, Martin, Coil)
(please see Kathy Kornei’s poster)
Clump
area
Petrosian
area
High Σ: v = -200 km/sec
Low Σ: v = -30 km/sec
• 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, SSFR, demographics.
AGN Outflows @ z~2-3
(Hainline et al. 2010)
(Hainline, Greene, Steidel)
(please talk to Kevin Hainline)
• 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.
Radiative Feedback: LyC and
Lya Escape
Galaxies and the Ionizing Budget
• 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.
(Bouwens et al. 2010)
Measuring fesc
• Unfortunately, at the epoch of
reionization, the Lya 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.
(Vanzella et al. 2010)
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
LyC
UV
(Nestor et al. 2011)
NB3640 Detections: LAE Examples
LyC
Lya
UV
(Nestor et al. 2011)
NB3640 Detections: FUV/FLyC
• NB3640-R  Probe of FUV/FLyC flux
density ratio.
LyC/UV
• 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).
UV
(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=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).
Escape of Lya @ z~3
(Kornei, Steidel)
(Please talk to Kathy Kornei)
• Consider Lya escape fraction, fesc,Lya:
fesc,Lya = LLya,obs/LLya,int
• Measure LLya,obs. Infer LLya,int based on
SFR (i.e. SFRNionLHa LLya,int ).
• Average value of fesc,Lya is ~10%. Strong
correlation between fesc,Lya and E(B-V).
•Suggests well mixing of dust and gas in
ISM.
(Kornei et al. 2010)
• Due to slit losses, must repeat analysis
using Lya NB imaging.
Physical Conditions in Highredshift galaxies
HII Regions
Rest-frame Optical Spectra
• Emission-line set: [OII], Hb
[OIII], Ha, [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]}
SDSS galaxy at z=0.09
• Electron temperature
{[OIII] ratios}
• Dust extinction
{Balmer line ratios}
Rest-frame Optical Spectra
• Emission-line set: [OII], Hb
[OIII], Ha, [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 restframe 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 Lya emitters.
• CGE team members: Nate Ross
(UCLA); Brian Siana (Caltech); Alaina
Henry, Crystal Martin (UCSB)
Near-IR Spectra of High-z Galaxies
(Hainline et al. 2009)
(Hainline, Coil)
(please talk to Kevin Hainline)
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.
Future Observations
• Keck/MOSFIRE: Multi-Object
Spectrometer for Infra-Red
Exploration; co-Pis: McLean
(UCLA) and Steidel (Caltech)
• Near-IR (0.9-2.5 mm) 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)
http://www.astro.ucla.edu/~irlab/mosfire/
(Maiolino et al. 2008)
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).
AGN Demographics
Future Plans: M-Z w/ MOSFIRE
(Hainline et al. 2011)
(Hainline, Greene)
(please talk to Kevin Hainline)
• 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.
Galaxy Structural Parameters
(Nagy et al. 2011; Law et al. 2011)
Galaxy Morphology at z~1.5-3.0
(Law, Nagy, Steidel)
(please talk to David Law)
• WFC3/IR F160W imaging for ~300 z~1.5-3.0 UV-selected galaxies.
• Measurement of galaxy structural parameters, connection with feedback
parameters.
(Nagy et al. 2011; Law et al. 2011)
Galaxy Morphology at z~1.5-3.0
(Law, Nagy, Steidel)
(please talk to David Law)
• Measure mass-radius relation at z~1.5-3.0.
• Demonstrate evolution: smaller radius at fixed stellar mass, consistent with (1+z)-1.
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 starforming regions (metallicity, dust extinction, etc.) with MOSFIRE.
• Come visit UCLA, give a talk at our extragalactic reading group!