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Gamma-Rays and BlazarsGamma-Rays and BlazarsMore Work for Variable Star ObserversMore Work for Variable Star Observers
Gordon G. SpearGordon G. Spear
Sonoma State UniversitySonoma State University
What are Gamma-rays?What are Gamma-rays?
Just photons, but with very high Just photons, but with very high energiesenergies
Photons with energies billions of times Photons with energies billions of times greater than visible light photonsgreater than visible light photons
Natural sources of Gamma-raysNatural sources of Gamma-rays Man made sources of Gamma-raysMan made sources of Gamma-rays Gamma-rays from spaceGamma-rays from space
How are Gamma-rays How are Gamma-rays characterized?characterized?
Gamma-rays are characterized by the Gamma-rays are characterized by the energy of individual photons.energy of individual photons.
Energies generally measured in MeV and Energies generally measured in MeV and GeV (millions and billions of eV).GeV (millions and billions of eV).
Infrared photons have energies on the Infrared photons have energies on the order of eV.order of eV.
One erg is about 600 billion eV.One erg is about 600 billion eV. The erg and the mosquito?The erg and the mosquito?
Different Types of EMRDifferent Types of EMRTYPE(TYPICAL)
WAVEL ENGTH
(CM)
FREQUENCY
(HZ)
ENERGY
(MEV)
Radio(21 cm, 1.4 GHz)
21 1.42E+09 5.90E-12
Visible(5500 A, green)
5.50E-05 5.45E+14 2.25E-06
X-ray(1 KeV)
1.24E-07 2.42E+17 1.00E-03
Gamma-ray(100 MeV)
1.24E-12 2.42E+22 100
(1 GeV) 1.24E-13 2.42E+23 1.00E+03
(1 TeV) 1.24E-16 2.42E+26 1.00E+06
Compton GRO and EGRETCompton GRO and EGRET
Compton Gamma Ray Observatory Compton Gamma Ray Observatory (CGRO)(CGRO)
Launched in 1991Launched in 1991 Re-entered Earth atmosphere in 2000Re-entered Earth atmosphere in 2000 Energetic Gamma Ray Experiment Energetic Gamma Ray Experiment
Telescope (EGRET)Telescope (EGRET) First all-sky survey in energy range 30 First all-sky survey in energy range 30
MeV to 10 GeVMeV to 10 GeV
Deployment of CGRO from the Deployment of CGRO from the Space ShuttleSpace Shuttle
The Objects in the Gamma-Ray SkyThe Objects in the Gamma-Ray Sky
Milky Way glow from cosmic ray Milky Way glow from cosmic ray interactions with dustinteractions with dust
Point sources in the Milky Way are Point sources in the Milky Way are Gamma-ray pulsars (SNRs)Gamma-ray pulsars (SNRs)
Point sources outside the Milky Way are Point sources outside the Milky Way are AGNsAGNs
Some point sources remain unidentifiedSome point sources remain unidentified
The EGRET Gamma-Ray SourcesThe EGRET Gamma-Ray Sources
GLAST and the LATGLAST and the LAT Gamma-ray Large Area Space Telescope (GLAST)Gamma-ray Large Area Space Telescope (GLAST) Substantial increases in sensitivity, energy range, Substantial increases in sensitivity, energy range,
and resolution over GROand resolution over GRO GLAST Burst Monitor (GBM)GLAST Burst Monitor (GBM) Large Area Telescope (LAT)Large Area Telescope (LAT) Scheduled for launch in 2006Scheduled for launch in 2006 5 year mission design, expected5 year mission design, expected 10 year useful 10 year useful
lifetimelifetime One year all-sky survey followed by pointed One year all-sky survey followed by pointed
observationsobservations
GLAST Specifications ComparisonGLAST Specifications Comparison
Representation of GLAST in OrbitRepresentation of GLAST in Orbit
AGNsAGNs
Active Galactic NucleiActive Galactic Nuclei Extragalactic objects that are more Extragalactic objects that are more
luminous than normal galaxiesluminous than normal galaxies The nucleus can be 10 to 100 times The nucleus can be 10 to 100 times
brighter than an entire normal galaxybrighter than an entire normal galaxy The underlying galaxy can appear The underlying galaxy can appear
relatively normal (when it can be seen)relatively normal (when it can be seen) Many different types or sub-classesMany different types or sub-classes
Some Categories of AGNsSome Categories of AGNs
Seyfert GalaxiesSeyfert Galaxies– Sy 1, Sy2Sy 1, Sy2
Radio GalaxiesRadio Galaxies– Narrow Line Radio Narrow Line Radio
Galaxies (NLRG... Galaxies (NLRG... FR I, FR II)FR I, FR II)
– Broad Line Radio Broad Line Radio Galaxies (BLRG)Galaxies (BLRG)
QuasarsQuasars– Broad Absorption Line Broad Absorption Line
Quasars (BALQ)Quasars (BALQ)– Steep Spectrum Radio Steep Spectrum Radio
Quasars (SSRQ)Quasars (SSRQ)– Flat Spectrum Radio Flat Spectrum Radio
Quasars (FSRQ)Quasars (FSRQ) BlazarsBlazars Optically Violent Optically Violent
Variables (OVV)Variables (OVV)
A Typical QuasarA Typical QuasarPKS 1117-248PKS 1117-248
General Characteristics of General Characteristics of AGNsAGNs
ExtragalacticExtragalactic More luminous than normal galaxiesMore luminous than normal galaxies Generally point sources (stellar Generally point sources (stellar
appearance)appearance) Some exhibit jetsSome exhibit jets Bright in X-rays and Gamma-raysBright in X-rays and Gamma-rays All exhibit variability at some level!All exhibit variability at some level!
AGN UnificationAGN Unification
All AGN are manifestations of the same All AGN are manifestations of the same physical phenomenonphysical phenomenon
This phenomenon is the accretion disk This phenomenon is the accretion disk and jets associated with a and jets associated with a supermassive black holesupermassive black hole
The different appearances are simply The different appearances are simply due to the orientation of the jets and due to the orientation of the jets and disk to our line of sightdisk to our line of sight
Artistic Impression of an AGNArtistic Impression of an AGN
Voyage into an AGNVoyage into an AGNA SimulationA Simulation
Starts 100s of Mpc Starts 100s of Mpc away from AGNaway from AGN
Underlying galaxy is a Underlying galaxy is a spiral (20000 stars)spiral (20000 stars)
The AGN engine has The AGN engine has been switched offbeen switched off
Size scale changes by Size scale changes by 10 orders of magnitude10 orders of magnitude
QuickTime™ and aGIF decompressor
are needed to see this picture.
AGN Unification TaxonomyAGN Unification Taxonomy
Some Typical Optical SpectraSome Typical Optical Spectra
The BlazarsThe Blazars The blazars appear to be AGN for which the The blazars appear to be AGN for which the
jets are pointing directly at us.jets are pointing directly at us. We are looking directly down the throat of the We are looking directly down the throat of the
dragon!dragon! Spectra (SEDs) have bright compton peak in Spectra (SEDs) have bright compton peak in
addition to the typical AGN synchrotron peak.addition to the typical AGN synchrotron peak. These are the only prominent point sources in These are the only prominent point sources in
the Gamma-ray sky. (Gamma loud)the Gamma-ray sky. (Gamma loud) Beams of particles moving at relativistic Beams of particles moving at relativistic
speeds produce intense beams of Gamma-speeds produce intense beams of Gamma-rays.rays.
These are the most variable of the AGNs.These are the most variable of the AGNs.
AGN Variability?AGN Variability?
All AGNs appear to be variable at some All AGNs appear to be variable at some levellevel
The emission lines vary in strengthThe emission lines vary in strength The continuum levels vary in brightnessThe continuum levels vary in brightness Variability has been documented over Variability has been documented over
decades, years, months, weeks, days, decades, years, months, weeks, days, and even hoursand even hours
Characteristics of AGN VariabilityCharacteristics of AGN Variability
Periodicity has NOT been convincingly Periodicity has NOT been convincingly demonstrated!demonstrated!
Slow, longterm irregular changesSlow, longterm irregular changes Outbursts (flares) and declinesOutbursts (flares) and declines General increase in variability for shorter General increase in variability for shorter
wavelengths (higher energy photons)wavelengths (higher energy photons) General increase in variability for longer time General increase in variability for longer time
scalesscales Apparent increase in variability with luminosityApparent increase in variability with luminosity Apparent increase in variability with redshiftApparent increase in variability with redshift
AGN Variability DataAGN Variability Data
Available observationsAvailable observations– Longterm (few per year)Longterm (few per year)– Intraday (few per week)Intraday (few per week)– Microvariability (many Microvariability (many
per hour)per hour)
Lightcurve classificationLightcurve classification– OutburstsOutbursts– DeclinesDeclines– Outbursts and declinesOutbursts and declines
The blazarsThe blazars– Most variable of the Most variable of the
AGNsAGNs– Amplitudes to 4 Amplitudes to 4
magnitudes or moremagnitudes or more– Can exhibit detectable Can exhibit detectable
variations from night-to-variations from night-to-night and within a nightnight and within a night
A Blazar with a Long History of Observation
B2 1308+326outbursts
B2 1215+303declines
B2 1215+303outbursts and
declines
PG 0804+762non-blazar AGN
Intraday Variability
Mrk 5010.1 mag miniflare
BL Lac0.4 mag in 30 minutes
The AAVSO has blazar data!The AAVSO has blazar data!
SSUO data for 3C 66ASSUO data for 3C 66A(2002-2002)(2002-2002)
Observing Techniques for Observing Techniques for AGNsAGNs
Just like variable stars!Just like variable stars! Visual observations can detect outbursts Visual observations can detect outbursts
and declines.and declines. CCD images which include a photometric CCD images which include a photometric
sequence can be measured. (BVRI filters sequence can be measured. (BVRI filters preferred)preferred)
Robotic telescope systems can be Robotic telescope systems can be extremely efficient, consistent, and extremely efficient, consistent, and productive.productive.
Opportunities Provided by Opportunities Provided by GLASTGLAST
Detect the Gamma-rays that are directly Detect the Gamma-rays that are directly produced by the supermassive black hole produced by the supermassive black hole engine.engine.
Provide data to evaluate various theories of Provide data to evaluate various theories of jet production.jet production.
Detect and measure several thousand new Detect and measure several thousand new Gamma-loud blazars.Gamma-loud blazars.
Provide for true multi-wavelength blazar and Provide for true multi-wavelength blazar and AGN surveillance.AGN surveillance.
Enter the GTNEnter the GTN GLAST Telescope Network (GTN)GLAST Telescope Network (GTN) Collaboration of observatories and observers Collaboration of observatories and observers
to obtain observations of AGNsto obtain observations of AGNs Professional astronomers, amateur Professional astronomers, amateur
astronomers, studentsastronomers, students Establish base line variability and coordinate Establish base line variability and coordinate
multi-wavelength campaignsmulti-wavelength campaigns Provide fundamental scientific data that will Provide fundamental scientific data that will
support and complement the GLAST missionsupport and complement the GLAST mission
The Goals for the GTNThe Goals for the GTN
Establish base-line activity levels and behavior for Establish base-line activity levels and behavior for gamma-loud blazarsgamma-loud blazars
Coordinate multi-wavelength campaigns (eventually Coordinate multi-wavelength campaigns (eventually include GLAST)include GLAST)
Establish and maintain data archive of blazar imagesEstablish and maintain data archive of blazar images Establish and maintain database of brightness data Establish and maintain database of brightness data
(like the AAVSO database?)(like the AAVSO database?) Distribute announcements about blazar activity (a Distribute announcements about blazar activity (a
GCN for blazars?)GCN for blazars?) Encourage participation by professionals, amateurs, Encourage participation by professionals, amateurs,
and students; establish mentoring relationshipsand students; establish mentoring relationships
Participants in the GTN will...Participants in the GTN will...
Contribute a minimum of 1-2 observations each Contribute a minimum of 1-2 observations each monthmonth
Participate in coordinated campaigns 1-2 times each Participate in coordinated campaigns 1-2 times each yearyear– intraday campaignsintraday campaigns– microvariability campaignsmicrovariability campaigns
Have access to data in the GTN archivesHave access to data in the GTN archives Contribute to improved understanding of blazar Contribute to improved understanding of blazar
energy production (supermassive black holes, energy production (supermassive black holes, relativistic jets)relativistic jets)
Contribute to the success of the GLAST missionContribute to the success of the GLAST mission
http://glast.sonoma.edu/gtnhttp://glast.sonoma.edu/gtn
AAVSO ContributionsAAVSO Contributions GTN partnerGTN partner Add bright Gamma-loud AGNs (blazars) to Add bright Gamma-loud AGNs (blazars) to
AAVSO object listAAVSO object list Monitor program AGNs for outbursts and Monitor program AGNs for outbursts and
other activity and provide notification to other activity and provide notification to interested partiesinterested parties
Introduce and mentor new observers to the Introduce and mentor new observers to the process of variable star observationprocess of variable star observation
Establish robotic observatories for use by Establish robotic observatories for use by AAVSO members, students, and schoolsAAVSO members, students, and schools
http://glast.sonoma.edu/gtnhttp://glast.sonoma.edu/gtn