Gamma-Ray Probes of
the Star-Forming Universeand Cosmic-Ray History

Collaborators
Vasiliki Pavlidou
Tijana Prodanovic
Amy Lien 連雅琳
Brian Fields Fermi Symposium Nov 4, 2009

Gamma-Ray Probes ofthe Star-Forming Universeand Cosmic-Ray History

Collaborators
Vasiliki Pavlidou
Tijana Prodanovic
Amy Lien 連雅琳
Brian Fields Fermi Symposium Nov 4, 2009

Cosmic Rays
and theGauranteed Gamma-Ray Background
diffuse Fermi sky: Porter, Digel, Ackermann talks
Galactic plane dominates
due to cosmic-ray propagation
pcr pism → π 0 → γγ
working hypothesis: supernovae areengines of cosmic-ray acceleration
star formation

supernovae

cosmic rays

Brian Fields Fermi Symposium Nov 4, 2009

Cosmic Rays
and theGauranteed Gamma-Ray Background
diffuse Fermi sky: Porter, Digel, Ackermann talks
Galactic plane dominates
due to cosmic-ray propagation
pcr pism → π 0 → γγ
working hypothesis: supernovae areengines of cosmic-ray acceleration
star formation

supernovae

cosmic rays

★ resolved star-forming galaxies:

new cosmic-ray laboratory Pavlidou & BDF 01;
Knodlseder, Bechtol, Karlsson talks

Brian Fields Fermi Symposium Nov 4, 2009

Cosmic Rays
and theGauranteed Gamma-Ray Background
diffuse Fermi sky: Porter, Digel, Ackermann talks
Galactic plane dominates
due to cosmic-ray propagation
pcr pism → π 0 → γγ
working hypothesis: supernovae areengines of cosmic-ray acceleration
star formation

supernovae

cosmic rays

★ resolved star-forming galaxies:

new cosmic-ray laboratory Pavlidou & BDF 01;
Knodlseder, Bechtol, Karlsson talks★ but most galaxies unresolved:

guaranteed contribution to diffuse
background Pavlidou & BDF 02; Prodanovic & BDF 06
Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History

Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History
galaxy:• eachgamma spectrum: pionic (Galactic)

Abdo et al 2009

Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History
galaxy:• eachgamma spectrum: pionic (Galactic)

feature! pion bump
Abdo et al 2009

Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History
galaxy:• eachgamma spectrum: pionic (Galactic)
gamma luminosity: scaling law

Lγ ∼ Φcr Ntargets ∼ (SN rate) × Mgas

feature! pion bump
Abdo et al 2009

Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History
galaxy:• eachgamma spectrum: pionic (Galactic)
Lγ ∼ Φcr Ntargets ∼ (SN rate) × Mgas

• cosmic star-forming emissivity

Lγ ∼ (cosmic SN rate) "Mgas #cosmic supernova rate
today: from cosmic star-formation rate
future: directly count SNe to z~1
Lien & BDF 09

cosmic star-form rate

gamma luminosity: scaling law

redshift z
Hopkins & Beacom 2006
Brian Fields Fermi Symposium Nov 4, 2009

Fermi Star-Forming Signal:
Cosmic-Ray Source History
galaxy:• eachgamma spectrum: pionic (Galactic)
Lγ ∼ Φcr Ntargets ∼ (SN rate) × Mgas

• cosmic star-forming emissivity

Lγ ∼ (cosmic SN rate) "Mgas #cosmic supernova rate
today: from cosmic star-formation rate
future: directly count SNe to z~1
Lien & BDF 09! intensity• total diffusecIγ ∼4π

cosmic star-form rate

gamma luminosity: scaling law

dt Lγ

redshift zHopkins & Beacom 2006

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted✓amplitude: substantial

part of preliminary Fermi
signalCurves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep
Points: Ackerman talk,url http://www-conf.slac.stanford.edu/tevpa09Ackermann090714v2.ppt

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted✓amplitude: substantial

part of preliminary Fermi
signal✓physics: probes cosmic
star formation: source
luminosity vs density
evolution

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep
Points: Ackerman talk,url http://www-conf.slac.stanford.edu/tevpa09Ackermann090714v2.ppt

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted✓amplitude: substantial

part of preliminary Fermi
signal✓physics: probes cosmic
star formation: source
luminosity vs density
evolution

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep
Points: Ackerman talk,url http://www-conf.slac.stanford.edu/tevpa09Ackermann090714v2.ppt

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted✓amplitude: substantial

part of preliminary Fermi
signal✓physics: probes cosmic
star formation: source
luminosity vs density
evolution

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep
Points: Ackerman talk,url http://www-conf.slac.stanford.edu/tevpa09Ackermann090714v2.ppt

Brian Fields Fermi Symposium Nov 4, 2009

Theory vs Observation
Preliminary Status✓shape: Galactic/pionicfeature redshifted✓amplitude: substantial

part of preliminary Fermi
signal✓physics: probes cosmic
star formation: source
luminosity vs density
evolution✓angular dist: ~isotropic,
but should cluster likegalaxies Ando & Pavlidou 09

Curves: Pavlidou & BDF 02; Pavlidou, Prodanovic, & BDF in prep
Points: Ackerman talk,url http://www-conf.slac.stanford.edu/tevpa09Ackermann090714v2.ppt

Brian Fields Fermi Symposium Nov 4, 2009

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SNcosmic rays

Brian Fields Fermi Symposium Nov 4, 2009

gamma rays

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SN

cosmic rays

gamma rays

• Guaranteed and important diffuse Fermi signal!
spectral feature: redshifted Galactic (pionic) peaksignal amplitude: probes of cosmic star formation

Brian Fields Fermi Symposium Nov 4, 2009

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SNcosmic rays

gamma rays

• Guaranteed and important diffuse Fermi signal!
spectral feature: redshifted Galactic (pionic) peaksignal amplitude: probes of cosmic star formation• Fermi resolved star-forming galaxies will calibrate
Milky Way diffuse, LMC, starbursts, M31?

Brian Fields Fermi Symposium Nov 4, 2009

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SNcosmic rays

gamma rays

• Guaranteed and important diffuse Fermi signal!
spectral feature: redshifted Galactic (pionic) peaksignal amplitude: probes of cosmic star formation• Fermi resolved star-forming galaxies will calibrate
Milky Way diffuse, LMC, starbursts, M31?

• star-forming gammas are “foreground” for other sources
guaranteed: AGN; hoped-for: dark matter, structure-formation cosmic rays

Brian Fields Fermi Symposium Nov 4, 2009

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SNcosmic rays

gamma rays

• Guaranteed and important diffuse Fermi signal!
spectral feature: redshifted Galactic (pionic) peaksignal amplitude: probes of cosmic star formation• Fermi resolved star-forming galaxies will calibrate
Milky Way diffuse, LMC, starbursts, M31?

• star-forming gammas are “foreground” for other sources
guaranteed: AGN; hoped-for: dark matter, structure-formation cosmic rays

• cosmic-ray feedback on cosmology
energy/pressure/ionization source, primordial lithium problem

Brian Fields Fermi Symposium Nov 4, 2009

Gamma Probes of Cosmic Star-Formation& Cosmic-Ray History
star-forming galaxies

SNcosmic rays

gamma rays

• Guaranteed and important diffuse Fermi signal!
spectral feature: redshifted Galactic (pionic) peaksignal amplitude: probes of cosmic star formation• Fermi resolved star-forming galaxies will calibrate
Milky Way diffuse, LMC, starbursts, M31?

• star-forming gammas are “foreground” for other sources
guaranteed: AGN; hoped-for: dark matter, structure-formation cosmic rays

• cosmic-ray feedback on cosmology
energy/pressure/ionization source, primordial lithium problem• stay tuned!
Brian Fields Fermi Symposium Nov 4, 2009