Spitzer Survey of Stellar Structure in Galaxies (S 4 G, PI Sheth ) : - - PowerPoint PPT Presentation

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Spitzer Survey of Stellar Structure in Galaxies (S 4 G, PI Sheth ) : - - PowerPoint PPT Presentation

Jan 01, 2023 177 likes •524 views

Spitzer Survey of Stellar Structure in Galaxies (S 4 G, PI Sheth ) : structural decompositions Eija Laurikainen Univ. of Oulu; FINCA, Univ. of Turku Decomposition team: Heikki Salo Eija Laurikainen Jarkko Laine Sebastien Comer on Dimitri

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Spitzer Survey of Stellar Structure in Galaxies (S4G, PI Sheth):

structural decompositions

Eija Laurikainen

  • Univ. of Oulu; FINCA, Univ. of Turku

Decomposition team: Heikki Salo

Eija Laurikainen Jarkko Laine Sebastien Comer´

  • n

Dimitri Gadotti

To appear in Salo et al. (2013)

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Sample:

  • Radial velocity in radio ν < 3000 km s−1 (equivalent to D=41 Mpc)
  • Integrated blue magnitude mBcorr < 15.5 mag
  • Angular diameter D25 > 1’
  • Galactic latitude > 300

⇒ N=2352 galaxies (+ 62 in the same frames)

Data:

  • IRAC images at 3.6 and 4.5 µm wavelengths
  • Map the galaxies up to 1.5 x D25
  • Surface density limit: µm(AB)3.6 ∼ 27 mag arcsec−2
  • Pixel resolution (3.6 µm) = 0.75” (for sampling 1.2”)

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Decomposition approach:

Use GALFIT (Peng et al. 2010)

  • Levenberg-Marguadt algorithm:

χ2 = 1 N X

x

X

y

[OBS(x, y) − MODEL(x, y)]2 σ(x, y)2 (1) ⇒ minimize χ2 between observed and model images ⇒ model image convolved with the image PSF

  • Use generalized ellipses for isophotes (C=0):

r(x′, y′) = |x′ − x0|C+2 + ˛ ˛ ˛ ˛ y′ − y0 q ˛ ˛ ˛ ˛

C+2! 1 C+2

(2)

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Fitting functions:

  • S´

ersic function (bulge) :

Σ(r) = Σe exp “ −κ h (r/re)1/n − 1 i” (3)

  • Exponential function (disk):

Σ(r) = Σo exp(−r/hr) (4)

  • Exponential function (edge-on disk):

Σ(rx, rz) = Σo rx hr K1 „rx hr « sech2(rz/hz), (5)

  • Modified Ferrers function (bar, β=0, α=2):

Σ(r) =  Σ0 ˆ 1 − (r/rout)2−β˜α r < rout r ≥ rout (6)

  • PSF-convolved point source (unresolved central source)

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What do we need:

  • Mosaicked science images (no none pixel values; PI)
  • PSF-image (oversampled, composite over rot. angles; Jarret)
  • Sigma-images (created from PI weight images)
  • Mask-images (created with SExtractor, edited by hand)
  • Orientation parameters, sky background, galaxy center

⇒ important to use those given with the decompositions

Running the decompositions:

  • Use GALFIDL (Salo)

⇒ creation of σ images ⇒ semiautomatic filling of the input files ⇒ visualization of the outcome

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Sky background (P4):

⇒ Decompositions only for galaxies with large enough FOV

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Orientation parameters (P4):

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  • 200
  • 100

100 200

  • 200
  • 100

100 200

NGC7098

  • 200
  • 100

100 200

  • 200
  • 100

100 200

LEDA: pa,inc= 61.9 59.2

  • 200
  • 100

100 200

  • 200
  • 100

100 200

S4G: pa,inc= 72.2 55.0

/home/heikki/S4G_BARS.dir/s4g_barlen_flatimage_100511.dir/NGC7098_flat heikki@hiisi.oulu.fi Tue May 10 15:26:50 2011

0.0 0.2 0.4 0.6 0.8 1.0 b/a (Leda) 50 100 150 200 250 Number ALL BT<15 0.0 0.2 0.4 0.6 0.8 1.0 b/a (Pipeline 4) 50 100 150 200 250 Number ALL BT<15

LEDA P4 LEDA b/a P4 b/a More reasonable

Comparison of LEDA and P4 orientations:

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What kind of decompositions:

(1) Automatic single S´ ersic fits (2) Automatic S´ ersic+expo fits (BD) (3) Individually checked bulge/disk/bar/nucleus fits (BDbarn): BD / BDn BDD / BDDn BDbar / BDbarn DDbar / DDbarn Dbar / Dbarn DD / DDn D / Dn Similar edge-on models

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How to show the profiles: an exponential disk

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Exponential disk + Ferrers bar

⇒ highlights non-axisymmetric structures; (Laurikainen et al. 2005) ⇒ important to look at: the profile and the model image

Fitting based on χ2, but in final model selection not critical

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Examples of the decompositions:

NGC 3938 [SA(s)c]: bulge/disk (BD)

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NGC 0628 [SA(s)c]: bulge/disk (BD) ⇒ PSF added

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NGC 1357 [(R’L)SA(rs)0/a]: bulge/disk/disk (BDD)

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NGC 2684 [SA(rs)b]: bulge/disk (Dn)

⇒ S´ ersic / PSF

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Bars in bright galaxies: NGC 3266 [(RL)SB0o] (BDbar)

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Bars in bright galaxies: NGC 0936 [(L)SB(rs,bl)0+] (BDbar)

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Bars in bright galaxies: NGC 5101 [(R1R2’)SB(rs,nl?)0] (BDbar)

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Bars in very late-types: NGC 1688 [SB(s)dm] (Dbarn)

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Bars in very late-types: IC 3021 [dSB(s)0/a] (Dbarn)

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Bars in very late-types: NGC 3517 [SB(s)m] (dbar)

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Pure disk galaxies: NGC 3377A [Im] (D)

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Pure disk galaxies: NGC 0723 [(R’)SA(s)bc] (DD)

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  • 5

5 10 50 100 150 200 250

Edge-on’s excluded bd dbar d

  • 5

5 10 Hubble T 0.0 0.2 0.4 0.6 0.8 1.0 Fraction bd dbar d

/home/heikki/P4_JUTTU_PRO/fathi_s4g_compare2_bulge_fraction heikki@pc091079 Wed Oct 16 13:20:46 2013

Final multi-component fits

More than 20 types of ’final models’ (permutations of ’b’,’d’,’bar’,’n’...) Visual classifications from from Buta et al. (2013)

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6 7 8 9 10 11 12 log10 M* 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Fraction bd dbar d

  • 2
  • 1

1 2 3 mB -m3.6(AB) color 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Fraction bd dbar d

/home/heikki/P4_JUTTU_PRO/fathi_s4g_compare2_bulge_fraction_vs_mass heikki@pc091079 Wed Oct 16 13:23:51 2013

Strong function of galaxy mass Strong function of color

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  • 5

5 10 Hubble T 2 4 6 Bulge Sersic n

2-Component BD Final model L2007

  • 5

5 10 Hubble T 0.1 1.0 Re/hr

2-Component BD Final model L2007

/home/heikki/P4_JUTTU/P4_FIGURES.dir/p4fig_model_comparisons_talk_re_hr heikki@pc091079 Tue Mar 5 01:55:37 2013

Multi-component vs BD fits

’Bulge’+’Disk’ galaxies:

Inclusion of bar-component crucial in order to get correct ← bulge S´ ersic index ← Bulge effective radius/ disk scale length

Multi-component fits in agreement with our NIRS0S /OSUBSGS fits (Laurikainen et al. 2007)

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non-barred ( 320)

  • 5

5 10 Hubble T 2 4 6 8 n

BD Final

barred ( 213)

  • 5

5 10 Hubble T 2 4 6 8 n

BD Final

Final: bar/nonbar

  • 5

5 10 Hubble T 2 4 6 8 n

bar non-bar

non-barred

  • 5

5 10 Hubble T 0.1 1.0 10.0 Re (kpc)

BD Final

barred

  • 5

5 10 Hubble T 0.1 1.0 10.0 Re (kpc)

BD Final

Final: bar/nonbar

  • 5

5 10 Hubble T 0.1 1.0 10.0 Re (kpc)

bar non-bar

/home/heikki/P4_JUTTU_PRO/p4fig_finalsample_model_comparisons_bar_nobar heikki@pc091079 Mon Aug 5 12:05:42 2013

An other way of showing the effect of bars:

⇒ automatic BD-fitting: does not work for barred galaxies ⇒ final models: similar in barred/non-barred galaxies

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  • 5

5 10 T (Buta) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Fraction

Bar in decomposition SB IB SB + SAB IB + IAB

/home/heikki/P4_JUTTU_PRO/p4fig_finalsample_model_fractions_korea_bar_tbuta heikki@pc091079 Wed Oct 16 12:34:07 2013

Bars in decompositions/classifications

⇒ similar distributions among Hubble types ⇒ more bars in classification: very faint bars not fitted

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6 7 8 9 10 11 12 log10M* 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Fraction

Bar in decomposition SB IB SB + SAB IB + IAB

Barazza et al. OPT

/home/heikki/P4_JUTTU_PRO/p4fig_finalsample_model_fractions_korea_bar_mstar heikki@pc091079 Wed Oct 16 12:34:07 2013

Bar fractions and galaxy mass:

⇒ fbar strong function of galaxy mass ⇒ but fbar significant also in faint galaxies ⇒ consistent with Barrazza et al. (2008) for log10M>9.5

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IRSA

IMPORTANT MANY P4 MODELS DONE BEFORE FINAL P1 IMAGES

⇒ need to be sure to use correct mask-files etc.

All input data needed in decompositions: (“IDE” = galaxy designation)

IDE.phot.1_nonan.fits IDE.1.finmask_nonan.fits IDE.phot.1_sigma.fits_ns PSF-1.composite.fits

Output files from 3 different decompositions: “MODEL

”

IDE_MODEL.outgal IDE_MODEL.outgal_subcomps.fits IDE_MODEL.outgal_profile.pdf IDE_MODEL.outgal_residual.pdf 29

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Pictorial web-database

Main page List of 2331 S4G galaxies http://www.oulu.fi/astronomy/S4G P4/MAIN101112.dir/main101112.html

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Clicking on galaxy name (’NGC1415’) ⇒ opens a decomposition page INDEX-pages for 100 galaxies near NGC1415 Iconic view of available data

1 2.cm 2 3 4 5 6 7

1) P1 image 2) clipped mask image 3) clipped image 4) Deprojected image 5) Elliptical isophotes 6) Sky background 7) Decomposition

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Conclusions:

Suitable:

  • Properties of bulges and disks in a large galaxy mass range
  • Easy to do new decompositions

Limitations:

  • Pixel resolution (pix=0.75”, final FWHM ∼ 2”)

⇒ small bulges not always possible to separate from PSF ⇒ not very good for nuclear bars/rings/lenses

What kind of decompositions depends on the science goal! IRSA: now 200 gal., the rest Dec 2013

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