The Fundamental Plane of AGN Host Galaxies

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Measuring the Diffuse Extragalactic Background
Light as a function of redshift Cosmic History
of Star Formation Holy Grail of Observational
Cosmology (a geological record of all energy
generated throughout history of Universe) GLAST
will be a BLAST!
Matt Malkan, UCLA
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Malkan and Stecker 1998 2001
DIRB Predictions of Backwards Evolution Models
Start with local IR Luminosity functions, and
local Spectral Energy Distributions, Extended
into optical/UV Then add the tricky part
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Dust-corrected Global SFR History

• Pure luminosity evolution still not bad
  approximation, with all Ls evolving with cosmic
  star formation history
• Eg MRR 1999, with extinction corrections included

MM Stecker 98,
Fast
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Model predictions of Diffuse Photon Spectra
Redshifts z0,1,2,3
Fancy surface plot, also SMS 05 Simple extension
down to Lyman limit
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Models for z0 D O/IRB are getting
Well-constrained by COBE and deep counts
Too late to get Direct measurements At any
higher zs
SMS 05
Either baseline or fast evolution is
currently consistent with observations
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Predicted total optical depths as fcn of received
energy (at least 2 wiggles in LAT spectra
expected)
O/NIR bump starlight cool dust reradiation
Z3, with CMWB separated / Summed optical depth
as fcn of Z
Stecker,MM,Scully 2005
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LAT well designed to do most redshifts from 0.1
up to peak of cosmic energy generation Differences
between some models (eg fast vs. baseline) are
subtle? Good SNR at highest energies becomes
crucial
Energy (received) at which total t 1
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A few test cases show that this works on nearby
TeV sources, such as PKS 2155-304 (z0.17)
SMS 05
With simultaneous wide energy coverage, fit
absorbed (intrinsically straight) power law This
could also work with GRB spectra, with z known
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What are potential ambiguities?
DIRB(z) is a convolution of LF, SFR history
over redshift, stellar population and dust
properties ?Expect an increasingly focused
search through model parameter space Role of
Air Shower Experiments is Crucial in filling in
lower zs

• We assume that Blazar AGN spectra are
• featureless power laws,
• but there could be intrinsic (variable)
  curvature,
• Or internal absorption (Elliptical galaxy, hot
  AGN dust?)
• Study statistical samples of
• Blazar spectra at each z

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What if the observed Gamma-ray absorption Is
shown to disagree with Independent DIRB Estimates?
Dont Worry! An explanation has already been
published. It has something to do with broken
symmetries.
If that turns out, theyll be looking for cheap
airfares to Stockholm (Floyd hasnt been yet)
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IR Luminosity functions of galaxies at z up to
2.5 Great improvement from Spitzer Herschel
will soon do the same For far-IR

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MS98 models
Huge SFR ultraluminous starburst, at 25-60um

• More luminous spirals have FIR peaks which are
  stronger and hotter (IRAS)
• Trend continues into sub-mm ISOPHOT
• (Spinoglio, Malkan, Andreani 2002)

Dust reradiation peak
Starlight peak
Very low SFR, hardly any young stars