The SEDs of Interacting Galaxies

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The SEDs of Interacting Galaxies Lauranne Lanz Nicola Brassington, Andreas Zezas, Howard A. Smith, Matthew L. N. Ashby, Elisabete da Cunha, Christopher Klein, Patrik Jonsson, Chris Hayward Lars Hernquist, Giovanni Fazio Harvard-Smithsonian Center for Astrophysics [email protected] NGC 520: NUV, 3.6 µm, & 8.0 µm L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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The SEDs of Interacting Galaxies. NGC 520: NUV, 3.6 µ m , & 8.0 µ m. Lauranne Lanz Nicola Brassington , Andreas Zezas , Howard A. Smith, Matthew L. N. Ashby, Elisabete da Cunha, Christopher Klein, Patrik Jonsson , Chris Hayward Lars Hernquist , Giovanni Fazio - PowerPoint PPT Presentation

Transcript of The SEDs of Interacting Galaxies

Page 1: The  SEDs  of Interacting Galaxies

The SEDs of Interacting Galaxies

Lauranne LanzNicola Brassington, Andreas Zezas, Howard A. Smith, Matthew L. N. Ashby,

Elisabete da Cunha, Christopher Klein, Patrik Jonsson, Chris HaywardLars Hernquist, Giovanni Fazio

Harvard-Smithsonian Center for [email protected]

NGC 520:NUV, 3.6 µm, & 8.0 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Outline

• What is Spitzer Interacting Galaxy Survey (SIGS)?

• SED shapes• SED fitting• sSFR comparisons• Trends with interaction stage

N3226-N32273.6 µm, 4.5 µm, & 8 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Sample Selection• Keel-Kennicutt (Keel et al. 1985) “complete” and

“Arp” samples:– Selected based on association likelihood– Require |Δv|< 600 km s-1 to remove non-associated pairs

• Imposed distance constraint cz < 4000 km s-1

• Resulting sample: 111 galaxies in 50 systems

NGC 2976:NUV, 3.6 µm, & 8.0 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Observations

• Complete Spitzer coverage: – IRAC, MIPS, and nuclear IRS spectra

• Almost complete GALEX coverage• Some Herschel coverage• Ancillary data– WISE coverage– Some Chandra/XMM coverage– Hα fluxes

M51NUV, IRAC 3.6 µm, & SPIRE 250 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Sample Selection and Observation Set Benefits

• Not morphologically selected: large range of interaction parameters

• Not infrared selected: less active systems included• Not based on optical line diagnostics• UV and IR coverage gives complete SFR

NGC 470 & NGC 474:FUV, 3.6 and 4.5 µm, & 8.0 µm

NGC 520:NUV, 3.6 µm, & 8.0 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Example: M51 and NGC 3430/3424

SPIRE 250 µm

IRAC3.6 µm, 4.5 µm, 8 µm

GALEX FUV NUV

2MASSJ, H, Ks

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Photometry

• S-Extractor used to determine NUV and 3.6 µm apertures

SPIRE 250 µm

IRAC3.6 µm, 4.5 µm, 8 µm

GALEX FUV NUV

2MASSJ, H, Ks

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Photometry

• S-Extractor used to determine NUV and 3.6 µm apertures

• Fluxes determined in larger aperture in all bands• Uncertainty: Calibration and Poisson

SPIRE 250 µm

IRAC3.6 µm, 4.5 µm, 8 µm

GALEX FUV NUV

2MASSJ, H, Ks

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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SED shapes

Log(

νL ν /

L)

Log(

νL ν /

L)

Log(

νL ν /

L)

Log(

νL ν /

L)

M51 A

NGC 3424 NGC 3430

M51 B

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

Page 10: The  SEDs  of Interacting Galaxies

Two blackbodies + β=1.5 graybody

4367 K 356.2 K 28.6 K 4058 K 357.1 K 25.8 K

3572 K 303.5 K 29.2 K 3307 K 339.5 K 25.2 K

Log(

νL ν /

L)

Log(

νL ν /

L)

Log(

νL ν /

L)

Log(

νL ν /

L)

M51 A

NGC 3424 NGC 3430

M51 B

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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MagPhys SED-fitting Code

• Optical stellar from Bruzual & Charlot 2003 and infrared dust from da Cunha, Charlot, & Elbaz 2008 spectral libraries

• Energy absorbed in UV/optical is re-emitted in IR• No AGN contribution considered• Likelihood distributions constructed for model

parameters to determine best fit SED

Elisabete da Cunha’s talk this afternoon

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Fit SEDsLo

g( λ

L λ / L

)

Log(

λL λ

/ L)

sSFR

TwarmTcold

sSFR

TwarmTcold

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Fit SEDsLo

g( λ

L λ / L

)

Log(

λL λ

/ L)

sSFR

TwarmTcold

sSFR

TwarmTcold

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Fit comparisonsFIR β=1.5 gray-body temperature falls between SED-fitted warm and cold temperatures

The integrated 8-1000 µm 3-component fit agrees well with the dust luminosity determined from fitting the SED.

Log( LDust, SED / L) F

rac.

Diff

eren

ce

Log

( L8-

1000

µm, 3p

art /

L)

TWarm

TCold

TGraybody / K

T SED

/ K

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Log(sSFR/yr-1) SED Fitting

Log(

sSFR

/yr-1

) Pre

scrip

tion

Comparison of Specific Star Formation Rates

M51A

N 3430

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Trends with Interaction Stage

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Trends with Interaction Stage

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Trends with Interaction Stage

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Summary• SIGS will provide a sample of interacting

galaxies from first pass to coalescence with a range of interaction parameters.

IC 1801 and NGC 935NUV, 3.6 and 4.5 µm, & 8.0 µm

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Summary• With the first 10 groups with SPIRE data, we:– find a range of SED shapes, especially in the ratio

of MIR to optical/UV.– measured sSFR and temperatures using the

MagPhys (da Cunha et al. 2008) SED-fitting code.– find an increase in warm component temperature

with interaction stage, but no significant change in sSFR.

M81:NUV, 8.0 µm, & 250 µm

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011

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Thank you for the attention and stay tuned for more:• 40 more interacting groups

• Nuclear activity• Comparison with simulated systems

N3448 – U6016:FUV, 3.6 µm, 4.5 µm, & 8 µm

M101:NUV, 3.6 µm, & 8 µm

Cox et al. 2006

L. Lanz, Harvard-CFA, SED2011 Sept. 6, 2011