Gamma ray nova v407 cyg and fermi lat galactic plane transients
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Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients. C.C. Teddy Cheung (NRC Research Associate*) on behalf of the Fermi-LAT Collaboration *resident at Naval Research Lab. Heidelberg Galactic Binaries – 2010 Dec 3. Fermi-LAT Galactic Plane Transients.

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Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients

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Gamma ray nova v407 cyg and fermi lat galactic plane transients

Gamma-ray Nova V407 Cyg and Fermi-LAT Galactic Plane Transients

C.C. Teddy Cheung

(NRC Research Associate*)

on behalf of the

Fermi-LAT Collaboration

*resident at Naval Research Lab

Heidelberg Galactic Binaries – 2010 Dec 3


Fermi lat galactic plane transients

Fermi-LAT Galactic Plane Transients

Low Galactic latitude blazars in 1st LAT AGN Catalog

LAT Galactic plane (|b|<10o) transients from daily search*

*Excludes flaring from known sources like Cyg X-3 and Crab

2010 Dec 3 - Cheung


Counterpart search fermi j0910 5041

Counterpart Search - Fermi J0910-5041

  • Fermi J0910-5041

  • (Cheung et al. ATel #1788)

  • Gal. latitude, b = -1.2o

  • October 15, 2008 (10σ), 2 day gamma-ray flare

  • Gamma-ray flare 10x larger than average flux

  • Swift TOO within 1 day

68%

68%

LAT 95% error circle contains Swift XRT source (Landi et al. ATel #1822)

coincident w/ flat-spectrum radio source in AT20G & SUMMS (Sadler ATel #1843)

  • Background blazar? Blazar gamma-ray activity typically more ‘long lived’

  • Galactic origin? More follow-up necessary

2010 Dec 3 - Cheung


Counterpart search 3eg j0903 3531

Counterpart Search - 3EG J0903-3531

  • 3EG J0903-3531

  • (Hays et al. ATel #1771)

  • Gal. latitude, b = +7.7o

  • October 5, 2008 (10σ), 3 day gamma-ray flare

  • 5x above 3EG flux

  • Swift TOO within 2 days

68%

68%

Updated LAT 95% error circle (8 months) contains a flat-spectrum radio source that is detected with Swift/XRT

  • Other bright Galactic plane transients

  • Fermi J1057-6027 (Yasuda et al. Atel #2081) – no ID

  • Fermi J0109+6134 (Vandenbroucke et al. 2010) - blazar

Preliminary

2010 Dec 3 - Cheung


Fermi lat discovery of a nova

Fermi-LAT Discovery of a Nova

  • Fermi J2102+4542 (6-8σ) March 13-14(Cheung et al. Atel #2487)

  • Excellent γ-ray localization (r=3.7’), consistent with symbiotic binary V407 Cyg

  • Subsequent analysis found initial LAT detection on March 10, same day as nova discovery

    • First g-ray detection of a nova

    • White dwarf in binary system

LAT 0.2-100 GeV

PSR J2021+4026

1FGL

J2111.3+4607

Nova 2010

V407 Cygni

Abdo et al. 2010 Science, 329, 817

(arXiv:1008.3912)

Corresponding authors: Cheung, A.B. Hill, P. Jean, S. Razzaque, K.S. Wood

2010 Dec 3 - Cheung


Gamma ray nova v407 cyg and fermi lat galactic plane transients

V407 Cygni: a variable star

Symbiotic binary:

small white dwarf (WD) star and large red giant (RG) star orbiting each other closely

Variability can come from the binary motion, pulsations of the red giant (IR/optical), accretion disk around the white dwarf (UV)

Nova thermonuclear runaway on WD surface

Nova discovery by Nishiyama & Kabashima IAUC 2199 (2010); H. Maehara (Kyoto)

2010 Dec 3 - Cheung


Panchromatic lightcurves

Panchromatic Lightcurves

  • Optical peaks first

  • First γ-ray detection day of nova optical discovery

    • peak 3-4 days later

    • duration ~15 days

  • X-rays peak at ~30 days; substantial rise after γ-rays below detectability

  • Bright evolving radio source (3-140 GHz): ATel #2506, 2511, 2514, 2529, 2536, 2741, 2905

  • Asymmetric distribution of Red giant and wind radiation as seen by nova shell

2010 Dec 3 - Cheung


V407 cyg binary system

V407 Cyg Binary System

  • Evolved Red Giant (M6 III) with:

    • Mira-like pulsations (745 day period)

    • SiO maser emission, D-type symbiotic (wind-accreting)

    • Anomalous Li abundance

  • Probable distance ~2.7 kpc

  • Fast rise and decline of nova indicate massive WD (>1 Msun)

.

  • Orbital period uncertain; binary separation ~4 dayγ-ray peak

  • RG wind & nova shell velocities inferred from optical spectral line-width measurements

2010 Dec 3 - Cheung


V407 cyg binary system1

V407 Cyg Binary System

.

Asymmetric distribution of material from Red Giant wind

2010 Dec 3 - Cheung


Nova ray and x ray evolution

Nova γ-ray and X-ray Evolution

  • Nova shell initially freely expands into asymmetric dense medium

  • Shell toward RG slows down quickly

    • Gamma rays peak early when efficiency for pion and inverse-Compton processes is favorable

  • Shell decelerates slowly away from RG

    • Later X-rays peak, flux increasing with volume of shock-heated gas

White dwarf at center

Credit: S. Razzaque

2010 Dec 3 - Cheung


Ray spectrum and energetics

γ-ray Spectrum and Energetics

15-day average

  • Gamma-ray emission process could be:

    • pion: acceleratedp’s collide with ambient material producing0with prompt decay

    • inverse Compton: accelerated electrons up-scattering infrared photons from the red giant

2010 Dec 3 - Cheung


Nova v407 cygni highlights thoughts

Nova V407 Cygni Highlights & Thoughts

  • Some Fermi-LAT Galactic plane γ-ray transients still unidentified

  • V407 Cyg first γ-ray nova (white dwarf in binary system)

  • Fermi acceleration in nova shell; interaction with massive red giant wind plays important role

  • Shell evolution recapitulates SNR evolution in miniature, and scaled down in timescale

  • Gamma-ray nova V407 Cyg 2010 not necessarily unique; symbiotic binaries relatively common, novae are numerous

  • Related binary systems? GX 1+4 = red giant (M6 III) + neutron star. GRS 1915+105 K-giant + black black.

2010 Dec 3 - Cheung


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