Upload
frisco
View
40
Download
0
Embed Size (px)
DESCRIPTION
STUDYING STAR FORMATION ACROSS COSMIC TIME WITH VIRUS-P. Lyman- α Emitters at 2
Citation preview
STUDYING STAR FORMATION ACROSS COSMIC TIME WITH VIRUS-P
Guillermo A. BlancThe University of Texas at Austin
Lyman-α Emitters at 2<z<4 Spiral Galaxies
at z=0
IFUs in the Era of JWST, STScI, Baltimore – 10/28/2010
The Hobby-Eberly TelescopeDark Energy Experiment
MPE/USM:Ralf Bender
Niv Drory
Ulrich Hopp
Ralf Koehler
Helena Relke
Jochen Weller
Penn State University:Robin Ciardullo
Caryl Gronwall
Larry Ramsey
Don Schneider
AIP:Andreas Kelz
Volker Mueller
Martin Roth
Mathias Steinmetz
Lutz Wisotzki
Texas A&M:Darren DePoy
Steven Finkelstein
Jennifer Marshall
Nicolas Suntzeff
Other:
Donghui Joeng (Caltech)
Eric Gawiser (Rutgers)
Povilas Palunas (LCO)
University of Texas:Josh Adams
Guillermo Blanc
Mark Cornell
Taylor Chonis
Karl Gebhardt (PS)
Lei Hao
Gary Hill (PI)
Eiichiro Komatsu
Hanshin Lee
Phillip MacQueen
Jeremy Murphy
Marc Rafal (PM)
Masatoshi Shoji
• HETDEX will measure the power spectrum for 800,000 Lyman Alpha emitting galaxies (LAEs) at 1.8< z <3.5 over a volume of 3 Gpc3.
• From the power spectrum HETDEX will measure w(z)=pDE(z)/ρDE(z) with a 1% accuracy and the curvature “k” with a 0.1% accuracy at z=2-3
• High-z measurements are complementary to low-z measurements and allow to study evolution.
The Hobby-Eberly Telescope Dark Energy Experiment
MUSYC LAE in E-CDFS, R=25.7, z=3.085 Ly EW=200Å, (6 hr IMACS exposure)
• How do you find 800,000 LAEs?
i.e. You use VIRUS
Visible Integral-field Replicable Unit Spectrograph
You get a spectrum for every arcsec2 patch over 60 deg2 and you check if you see one.
VIRUS consists of 75 IFUs feeding 150 spectrographs on the HET 9.2m
100”
15.6’
VIRUS will be commissioned on early 2012
VIRUS-P: The Prototype• VIRUS Prototype IFU
• 1.7’x1.7’ FOV at McDonald 2.7m
• 1/3 filling factor
• Largest FOV of any existent IFU
• 4.2’’ diameter fibers on sky
• 3500-5800Å wavelength range
• Ly-Alpha @ 1.9 < z < 3.8
• R=1000 @ 5000Å
The HETDEX Pilot Survey• SURVEY DESIGN:
• 169 arcmin2 surveyed on COSMOS, GOODS-N, MUNICS-S2, and XMM-LSS fields
• Fields selected to have deep multi-wavelength broad-band imaging
• 6 position dither pattern ensures good field coverage
• Three 20 min exposures at each position• 2 hr of effective exposure time• 5σ flux limit of ~6x10-17 erg/s/cm2 for a
point-source emitting and unresolved line• Adams et al. 2010; Blanc et al. 2010,
Finkelstein et al. 2010 (next week on arxiv)
• GOALS:
1. HETDEX and VIRUS proof of concept
2. Create an LAE sample spanning a large redshift range, to study the properties of LAEs and the escape fraction of Lyα photons from galaxies, and their evolution with redshift.
DETECTION OF EMISSION LINES
• GROW DETECTION UNTIL S/N STOPS INCREASING
• POSITION GIVEN BY FIRST MOMENT OF LIGHT DISTRIBUTION
SOURCE CLASSIFICATION
• 2 step classification:1. Classification based
solely on the spectrum
2. Use broad-band flux of counterparts and Lyα line flux to apply EWrest> 20 Å criteria.
TYPICAL NARROW-BAND
LYMAN ALPHA EMITTERS Low-z GALAXIES
98 LAEs at 2<z<4 !!!
and ~400 low-z galaxies and AGN
Dust and the escape of Lyα
q = (Lyα / λ=1216)
• Favorable ISM configuration reduces Lyα quenching by dust.• No evidence of EW enhancement by clumpy dust distribution in multi-phase ISM.• LAEs fall above LBGs and should be considered as an upper envelope for the overall galaxy population.
Lyα Luminosity Function
THE GENERAL GALAXY POPULATION Lyα ESCAPE FRACTION
• Estimated by predicting Lyα luminosity expected given the SFR density history of the universe, and comparing to the integral of the Lyα Luminosity Function.
• Sharp transition from 100% down to 5% between z=5 and z=3. Best-fit transition redshift of 4.1 0.5
• Most likely due to dust build-up in galaxies.
Bouwens et al. 2009 Blanc et al. 2010 (submitted to ApJ)
HETDEX SAMPLE
• HETDEX is a blind spectroscopic survey of 60 deg2.– 800,000 LAEs at 1.8<z<3.5– 1,000,000 [OII], Hβ, [OIII] Emitters at z<0.5– 400,000 continuum galaxies– 250,000 MW stars with spectra– 2,000 galaxy clusters– 10,000 – 50,000 AGN at z<3.5– 10,000 LABs
• And whatever it is we are not looking for!!!!!!
P.I.: Guillermo A. Blanc (UT, Austin)Co.Is: Niv Drory (MPE, Garching) Neal Evans (UT, Austin)
Maximilian Fabricius (MPE, Garching) David Fisher (UT, Austin) Karl Gebhardt (UT, Austin) Lei Hao (Shanghai Observatory) Amanda Heiderman (UT, Austin) Gary J. Hill (UT, Austin) Shardha Jogee (UT, Austin) John Kormendy (UT, Austin) Irina Marinova (UT, Austin) Juntai Shen (Shanghai Observatory) Remco van den Bosch (UT, Austin) Timothy Weinzirl (UT, Austin) Mimi Song (UT, Austin)
• 32 Nearby Spiral Galaxies• 72 1.7’x1.7’ VIRUS-P Pointings• ~ 53,000 spectra: 3600 Å – 6850 Å• Spectral Resolution: 5 Å (120 km/s)• Coverage > 0.7 R25 for all galaxies• Median S/N=40 per fiber• High Resolution VIRUS-W (25 km/s)
MOTIVATION• HOW DO GALAXIES FORM AND EVOVLE?
FEEDBACK (SN, AGN, STARS)
SFR (BURST/ GENTLE CYCLE)MERGER (MAJOR/MINOR)
GAS ACRETION (HOT/COLD)
SECULAR PROCESSES
NGC 5194 (Blanc et al. 09)4
kpc
CENTRAL AGN
Crane et al. 1992
Bradley et al. 2004
DIFFUSE IONIZED GAS
WHAM (Madsen et al. 2006)
• DIG accounts for 11% of total Hα luminosity
LOCALIZED STAR FORMATION Hα
HII Regions + DIG HII Regions Only
THINGSWalter et al. 2008
VENGABlanc et al. 2010
BIMA SONGHelfer et al. 2003
RESULTS• 735 regions (D=170 pc) in the central 4.1 × 4.1 kpc2
• Lack of correlation with the atomic gas surface density, which saturates around 10 Mpc-2 .
• Clear correlation with the molecular gas surface density, which drives the total gas SFL
• Monte Carlo Fitting of total gas SFL parameters:– N = 0.85 ± 0.05– A = 10−1.31±0.02 = Depletion timescales of 2 Gyr– ε = 0.43 ± 0.02 dex.
• Consistent with a roughly constant SFE in GMCs, which is almost independent of the molecular gas surface density. NOT consistent with a N~1.5 slope.
• Good agreement with the theoretical SFL model of Krumholz et al. (2009).
ONGOING AND FUTURE WORK
• Extend analysis to the full VENGA sample:– Sample different regimes in density, Z, dynamics, etc.
• Intrinsic Scatter:– Search for extra parameters– Scatter in SFR indicators– Scale dependence and connection to MW studies.
• Extend study to denser environments in starburst and mergers:– Non-linear regime of the SFL– VIXENS (P.I. Amanda Heiderman)
VENGA MAP OF NGC 2903
THANK YOU!!