ithaca - 19 jun 2006 vc the irs gto ulirg program

Ithaca - 19 Jun 2006VC

The IRS GTO ULIRG ProgramThe IRS GTO ULIRG Program

0

5

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25

0.04 0.16 0.28 0.4 0.52 0.64 0.76 0.88 1

redshift

Current IRS ULIRG Sample

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26

58

93

60

3924

8 9 4 2 2 1 0 0 4 1 2 2 1 0 0 1 1 00

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0.04 0.16 0.28 0.4 0.52 0.64 0.76 0.88 1

redshift

all ULIRGs

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11.9 12.1 12.3 12.5 12.7 12.9 13.1 13.3

log LFIR

Current IRS ULIRG Sample

166

5540 30 22 10 9 4 2 0 4 0 0 1 10

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11.9 12.1 12.3 12.5 12.7 12.9 13.1 13.3

log LFIR

all ULIRGs


The IRS GTO ULIRG program - details The IRS GTO ULIRG program - details

Of the 110 sources Flux limited: 32 have S25 0.3 Jy and log LFIR 11.85 L.

We are observing all 32 in low and high-res modes. High redshift: 27 have z 0.3.

GTO1-: 12/27 are being observed in low and high-res. + GTO2 (all rest) High luminosity: 11 sources have log LFIR 12.5 L .

10/11 are being observed in low and high-res.. Mix of Far-IR colors: 68 are “cold” (S25/S60 < 0.2) and 21 are “warm”.

This is a higher fraction of warm sources than in a flux-limited survey (typically ≤ 10%).

GO Programs: Veilleux et al., Lutz et al., Imanishi et al., Verma et al. Sturtm et al.

Additional IRS spectroscopy of ~30 “Template” galaxies “usual suspects” Weedman et al. 2005, Brandl et al. 2006 (submitted), Devost et al.

2006 (in prep)


Diversity! in the mid-IR spectra

of ULIRGs

AGN

Starburst

Embedded


Rigopoulou et al. 1999

IRS Spectra of BGS Sources IRS Spectra of BGS Sources

Armus et al. 2006

ISO PHT-S spectra of BGS Sources ISO PHT-S spectra of BGS Sources


Spoon et al. 2004, A&A, 414,873

Arp220 Arp220


Normalized BGS spectra Normalized BGS spectra

Armus et al. 2006

Ithaca - 19 Jun 2006VC Armus et al. 2006

Quantifying the contributionQuantifying the contributionof of accretion to a SMBHaccretion to a SMBH - -and and a Stabursta Staburstto the total mid-IR fluxto the total mid-IR flux

AGN Tracer:AGN Tracer:•[NeV] at 14.3μm / 23.2μm (Ep~97eV)

Starburst Tracers:Starburst Tracers:•[NeII] at 12.83μm(Ep~21eV)

•Presence of PAHs6.2μm EQW


AGN

starburst

ULIRG

Armus et al. 2006

Quantifying the contributionQuantifying the contributionof the energy from the AGNof the energy from the AGNto the total IR luminosityto the total IR luminosity


starburst

ULIRG

AGN

[NeV] not detected in deeply obscured ULIRGs: Is the AGN NLR fully obscured?

[NeV] not detected in deeply obscured ULIRGs: Is the AGN NLR fully obscured?


• Rising slope of thermal emission from the AGN torus from 2-5μm due to grains radiating in near-equilibrium

• Excess over starlight at ~4-5μm“Laurent Diagram”

Alonso-Herrero et al. 2003

f(5μm)~10Jyz~0.004D~14Mpc

f(5μm)~7mJyz~0.9

D~5.8Gpc

FSC15307+3252

AGN thermal emission in mid-IR continuum AGN thermal emission in mid-IR continuum


Decomposition of the Infrared Spectrum

Core of the method Assume absorption cross sections from Li & Draine (2001) and an

MRN grain-size distribution Calculate the opacities of PAH, graphitic and smoothed

astronomical silicate grains.

Each dust component has a quasi-fixed temperature i.e.. the fitting process is really an expansion into several temperature basis components.

The number of dust components is fixed for the sample so that all galaxies are fit in a uniform manner.

In addition to a ~3500 K stellar blackbody and PAH component, we find that we need ~3 additional continuum dust components with T~400, ~150, and ~30 K to accurately fit the entire sample.

An AGN manifests its presence with the requirement of an additional hot dust component T~800K (Laurent et al. 2000)

Talk to Jason Marshall !Talk to Jason Marshall !


Decomposition of Arp220

TCold=31KTWarm=96KTHot=873K

LHot/LTotal=0.005L1-40/LTotal=0.19LPAH/LTotal=0.004


Decomposition of Mrk231

TCold=38KTWarm=151KTHot=486K

LHot/LTotal=0.13L1-40/LTotal=0.52LPAH/LTotal=0.006


Conclusions based on the BGS ULIRGs

AGN fraction estimates based on various methods


Quantifying the contributionQuantifying the contributionof the energy from the AGNof the energy from the AGNUsing the “Laurent Diagram”Using the “Laurent Diagram”

Armus et al. 2006

ithaca - 19 jun 2006 vc the irs gto ulirg program

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