Contiguous star-forming features in the outskirts of early-type - - PowerPoint PPT Presentation
2nd SELGIFS Advanced School on IFS Data Analysis on Integral-Field Spectroscopy Data Analysis Contiguous star-forming features in the outskirts of early-type galaxies Jean Michel Gomes Institute of Astrophysics and Space Sciences &
Institute of Astrophysics and Space Sciences
www.iastro.pt
Jean Michel Gomes & Polychronis Papaderos
Madrid, 21-25/11/2016
2nd SELGIFS Advanced School on IFS Data Analysis
J.M. Vílchez
S.F. Sánchez
and the CALIFA collaboration
* Type i, i+ & ii
◎ Similarity with Paleontology ◎ Analysis of the fossil records of galaxies, i.e. the previous generations of stars
Population Synthesis
YOUNG INT. OLD
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◎ Similarity with Paleontology ◎ Analysis of the fossil records of galaxies, i.e. the previous generations of stars
YOUNG INT. OLD
Population Synthesis
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◎ Similarity with Paleontology ◎ Analysis of the fossil records of galaxies, i.e. the previous generations of stars
YOUNG INT. OLD
F(λ) = Ʃj Mj Lj(λ) 10-0.4Aλ ⨂ G(v★,σ★)
Population Synthesis
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+ other terms to model the spectrum
F(λ) λ [Å] Starlight code (Cid Fernandes et al. 2005)
Population Synthesis
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SDSS - DR7
star-forming LINER Seyfert
Kewley et al. (2001) Kauffmann et al. (2003c)
Early-Type Galaxies 10
◎ Deceptively simple ◎ Ellipsoids ◎ Simple stellar population ~ globular clusters ◎ Age of the order of 10 Gyr ◎ LINER characteristics
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* What is the nature of the warm interstellar medium in ETGs?
AGN? Post-AGB stars? Residual SF? Shocks?
* Faint Nebular Emission - EW(Hα) <~ 3Å - Usually compatible with
Low Ionization nuclear emission-line regions (LINER) line-ratios in standard diagnostic diagrams
*This project mainly focus on the Post-AGB component for the
ionization mechanism in ETGs
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Data cube illustration from CALIFA
◎ MODULAR structure ◎ STARLIGHT spectral synthesis code ◎ ESO-MIDAS + Fortran standalone routines Tool developed at IA - Papaderos & Gomes Described in Gomes et al. 2016a
Computation
Emission- line maps
Pre- Processing
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Hα Flux Hα EW mean ☆ age mass mean ☆ age light
arcsec arcsec arcsec arcsec arcsec arcsec
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Gomes et al. 2016a
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Nucleus Extranuclear
Tentative classification scheme based on distinct EW zones
Type i 64 % S0’s : radially constant <EW(Hα)> ~ 1Å Type i+ 100% S0’s : ~10% of all ETGs in our sample Type ii 78 % E’s : very low (< 0.5 Å) EW(Hα) with positive radial gradients
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Way above the threshold for pAGB photoionization in the outskirts
Hα Flux Hα EW 18
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SSFR ~ 10-12 yr-1 & SFR ~ 0.1-0.3 M yr-1 - S0
EW(Hα)
SDSS images
NGC 1167 NGC 1349 NGC 3106
Gomes, Papaderos et al. 2016b
☉
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1) Spatially resolved analysis in type i+ galaxies 2) Faint spiral-like star-forming features detected in the outskirts of local type i+ ETGs (∼10% of the sample). 3) Empirical assessment of BPT emission-lines and aperture effects using CALIFA IFS data for type i+ & theoretical study based on a simple inside-out galaxy growth model.
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Photometric analysis (computation and subtraction of a 2D model) will be provided to the students using the unsharp- masked images. Identify spaxels within spiral-like SF features for NGC 0932 (NGC 0787 if time available)
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1- First task Based on 3D observed data cubes corrected for the systemic galaxy velocity (*_3D_OBS) Extract and sum-up the spectra from spaxels within spiral features (see photometric images). i) These summed-up spectra (corrected for the systemic galaxy velocity) will then be modeled with STARLIGHT, and the stellar SED will be subtracted in order to isolate the nebular emission. ii) From which finally BPT line-ratios have to be derived in order to confirm that H-alpha emission in the spiral-like arms/rims is due to photoionization by young OB stars.
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2- Second task Apply on this summed-up spectra RemoveYoung (see presentation on Wednesday) and discuss the effect that removal of the young stellar component has on the spectrum.
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