Gamma-ray Nova V407 Gamma-ray Nova V407 Cyg and Fermi-LAT Cyg and Fermi-LAT
Galactic Plane TransientsGalactic 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 TransientsFermi-LAT Galactic Plane Transients
LAT Galactic plane (|b|<10o) transients from daily search*
Low Galactic latitude blazars in 1st LAT AGN Catalog
2010 Dec 3 - Cheung
*Excludes flaring from known sources like Cyg X-3 and Crab
Counterpart Search - Fermi J0910-5041Counterpart 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)
2010 Dec 3 - Cheung
- Background blazar? Blazar gamma-ray activity typically more ‘long lived’
- Galactic origin? More follow-up necessary
Counterpart Search - 3EG J0903-3531Counterpart Search - 3EG J0903-3531
68% 68%
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
Updated LAT 95% error circle (8 months) contains a flat-spectrum radio source that is detected with Swift/XRT
Preliminary2010 Dec 3 - Cheung
Other bright Galactic plane transients
- Fermi J1057-6027 (Yasuda et al. Atel #2081) – no ID
- Fermi J0109+6134 (Vandenbroucke et al. 2010) - blazar
Fermi-LAT Discovery of a NovaFermi-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 First ray detection of a novaray detection of a nova White dwarf in binary systemWhite dwarf in binary system
1FGL J2111.3+4607
Nova 2010V407 Cygni
PSR J2021+4026
LAT 0.2-100 GeV
2010 Dec 3 - Cheung
Abdo et al. 2010 Science, 329, 817
(arXiv:1008.3912)
Corresponding authors: Cheung, A.B. Hill, P. Jean, S. Razzaque, K.S. Wood
V407 Cygni: a variable starV407 Cygni: a variable star
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
Symbiotic binary: small white dwarf (WD) star and large red giant (RG) star orbiting each other closely
2010 Dec 3 - Cheung
Nova discovery by Nishiyama & Kabashima IAUC 2199 (2010); H. Maehara (Kyoto)
Panchromatic LightcurvesPanchromatic Lightcurves
Asymmetric distribution of Red giant and wind radiation as seen by nova shell
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
★
2010 Dec 3 - Cheung
V407 Cyg Binary SystemV407 Cyg Binary System
.
2010 Dec 3 - Cheung
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 day γ-ray peak
RG wind & nova shell velocities inferred from optical spectral line-width measurements
V407 Cyg Binary SystemV407 Cyg Binary System
.
2010 Dec 3 - Cheung
Asymmetric distribution of material from Red Giant wind
Nova γ-ray and X-ray Evolution Nova γ-ray and X-ray Evolution
White dwarf at center
Credit: S. Razzaque
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
2010 Dec 3 - Cheung
γ-ray Spectrum and Energeticsγ-ray Spectrum and Energetics
15-day average
Gamma-ray emission process could be:
pion:pion: accelerated accelerated pp’s ’s collide with ambient collide with ambient material producingmaterial producing 00 with with prompt decayprompt decay• inverse Compton:inverse Compton: accelerated electrons up-accelerated electrons up-scattering infrared photons scattering infrared photons from the red giantfrom the red giant
2010 Dec 3 - Cheung
Nova V407 Cygni Highlights & ThoughtsNova 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