10/21/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

10/21/03 Prof. Lynn Cominsky 1

Class web site: Class web site: http://glast.sonoma.edu/~lynnc/courses/ahttp://glast.sonoma.edu/~lynnc/courses/a305305

Office: Darwin 329A and NASA E/POOffice: Darwin 329A and NASA E/PO

(707) 664-2655(707) 664-2655

Best way to reach me: Best way to reach me: [email protected]@charmian.sonoma.edu

Astronomy 305/Frontiers in Astronomy 305/Frontiers in AstronomyAstronomy


Group 8Group 8


Stellar evolution made simple – a Stellar evolution made simple – a reviewreview

Stars like the Sun go gentle into that good night

More massive stars rage, rage against the dying of the light

Puff!

Bang!

BANG!


Exploding StarsExploding Stars

At the end of a star’s life, if it is large enough, At the end of a star’s life, if it is large enough, it will end with a bang (and not a whimper!)it will end with a bang (and not a whimper!)

Supernova 1987A in

Large Magellanic Cloud

HST/WFPC2


Supernova RemnantsSupernova Remnants

Radioactive decay of chemical elements Radioactive decay of chemical elements created by the supernova explosioncreated by the supernova explosion

Vela Region

CGRO/Comptel


Neutron Stars: Dense cindersNeutron Stars: Dense cinders

Mass: ~1.4 solar massesRadius: ~10 kilometersDensity: 1014-15 g/cm3

Magnetic field: 108-14 gauss Spin rate: from 1000Hz to 0.08 Hz


Making a Neutron StarMaking a Neutron Star


Black holesBlack holes

Mass: > 3 to a few x 109 solar masses

Defined: an object where the escape velocityIs greater than the speed of light

Ve = (2 G m / r)1/2

Schwarzschild radius = 2 G m/c2

Rs = 3 km for the Sun


AccretionAccretion

• Powered by gravity, heated by friction• Black holes, neutron stars and white dwarfs in binaries• Accretion is 10% efficient

1 marshmallow= atomic bomb(about 10 kilotons)


AccretionAccretion Matter transfers Matter transfers

through inner through inner Lagrange point Lagrange point from normal star from normal star onto compact onto compact companioncompanion

Swirls around in Swirls around in accretion disk accretion disk

Blondin 1998

movie


Accretion moviesAccretion movies

Roche lobe overflowRoche lobe overflow

3D Simulations by John Blondin

Stellar wind captureStellar wind capture


Classifying BurstsClassifying Bursts In this activity, you will be given twenty In this activity, you will be given twenty

cards showing different types of burstscards showing different types of bursts Pay attention to the lightcurves, optical Pay attention to the lightcurves, optical

counterparts and other properties of the counterparts and other properties of the bursts given on the reverse of the cardsbursts given on the reverse of the cards

How many different types of bursts are How many different types of bursts are there? Sort the bursts into different there? Sort the bursts into different classesclasses

Fill out the accompanying worksheet to Fill out the accompanying worksheet to explain the reasoningexplain the reasoning behind yourbehind your classification schemeclassification scheme


Aitoff Projection & Galactic Aitoff Projection & Galactic Coordinates (1)Coordinates (1)


Aitoff Projection & Galactic Aitoff Projection & Galactic Coordinates (2)Coordinates (2)


Answers (1)Answers (1)

X-ray Bursters Soft Gamma-Ray Repeaters

Gamma ray bursts

0748-67 0526-66 0501+11

1636-53 1627-41 0656+79

1659-29 1806-20 1156+65

1728-34 1900+14 1338-80

1735-44 1525+44

1820-30 1935-52

1837+05 2232-73

1850-08 2359+08


Answers (2)Answers (2)

X = Gamma Ray Bursts= Soft Gamma Ray Repeaters

= X-ray Bursters


Distributions Distributions If sources are If sources are

located randomly located randomly in space, the in space, the distribution is distribution is called isotropiccalled isotropic

If the sources are If the sources are concentrated in a concentrated in a certain region or certain region or along the galactic along the galactic plane, the plane, the distribution is distribution is anisotropicanisotropic


What makes Gamma-ray Bursts?What makes Gamma-ray Bursts? X-ray BurstsX-ray Bursts

PropertiesProperties Thermonuclear Flash ModelThermonuclear Flash Model

Soft Gamma Repeaters Soft Gamma Repeaters PropertiesProperties Magnetar modelMagnetar model

Gamma-ray BurstsGamma-ray Bursts PropertiesProperties ModelsModels AfterglowsAfterglows Future Mission StudiesFuture Mission Studies


X-ray BurstsX-ray Bursts

Thermonuclear flashes on Neutron Star Thermonuclear flashes on Neutron Star surface – hydrogen or helium fusionsurface – hydrogen or helium fusion

Accreting material burns in shells, Accreting material burns in shells, unstable burning leads to thermonuclear unstable burning leads to thermonuclear runawayrunaway

Bursts repeat every few hours to daysBursts repeat every few hours to days Bursts are never seen from black hole Bursts are never seen from black hole

binaries (no surface for unstable nuclear binaries (no surface for unstable nuclear burning) or from (almost all) pulsars burning) or from (almost all) pulsars (magnetic field quenches thermonuclear (magnetic field quenches thermonuclear runaway)runaway)


X-ray Burst SourcesX-ray Burst Sources

Locations in Galactic CoordinatesLocations in Galactic Coordinatesbursters non-bursters Globular Clusters

• Most bursters arelocated in globularclusters or near theGalactic center• They are therefore relatively older systems


X-ray Burst Source PropertiesX-ray Burst Source Properties

Weaker magnetic dipole: B~10Weaker magnetic dipole: B~108 8 GG NS spin period seen in bursts NS spin period seen in bursts

~0.003 sec. ~0.003 sec. Orbital periods : 0.19 - 398 h from Orbital periods : 0.19 - 398 h from

X-ray dips & eclipses and/or optical X-ray dips & eclipses and/or optical modulationmodulation

> 15 well known bursting systems> 15 well known bursting systems Low mass companionsLow mass companions LLx x = 10= 103636 - 10 - 103838 erg/s erg/s

Neutron Stars in binary systemsNeutron Stars in binary systems


X-ray EmissionX-ray Emission

X-ray emission from accretion can be modulated by magnetic fields, unstable burning and spin

Modulation due to spin of neutron star can sometimes be seen within the burst


Thermonuclear Flash Model movieThermonuclear Flash Model movie


X-ray Burst SourcesX-ray Burst Sources

Burst spectra are thermal black-bodyBurst spectra are thermal black-body

Cominsky PhD 1981

L(t) = 4 R2 T(t)4

Radius Expansion

Temperature

2


Soft Gamma RepeatersSoft Gamma Repeaters

There are four of these objects known to There are four of these objects known to datedate

One is in the LMC, the other 3 are in the One is in the LMC, the other 3 are in the Milky WayMilky Way

LMC

SGR 1627-41


Making a magnetarMaking a magnetar


SGR EmissionSGR Emission

Emission from accretion can be modulated by magnetic fields

Modulation due to spin of neutron star can be seen within the burst

movie


Soft Gamma Repeater PropertiesSoft Gamma Repeater Properties

Superstrong magnetic dipole: B~10Superstrong magnetic dipole: B~1014-15 14-15 GG NS spin period seen in bursts ~5-10 sec, NS spin period seen in bursts ~5-10 sec,

shows evidence of rapid spin downshows evidence of rapid spin down No orbital periods – not in binaries!No orbital periods – not in binaries! 4 well studied systems + several other 4 well studied systems + several other

candidate systemscandidate systems Several SGRs are located in or near SNRsSeveral SGRs are located in or near SNRs Soft gamma ray bursts are from magnetic Soft gamma ray bursts are from magnetic

reconnection/flaring like giant solar flaresreconnection/flaring like giant solar flares LLx x = 10= 104242 - 10 - 104343 erg/s at peak of bursts erg/s at peak of bursts

Young Neutron Stars near SNRsYoung Neutron Stars near SNRs


SGR 1900+14SGR 1900+14

Strong burst Strong burst showing ~5 showing ~5 sec pulsessec pulses

Change in 5 s Change in 5 s spin rate spin rate leads to leads to measure of measure of magnetic fieldmagnetic field

Source is a Source is a magnetar!magnetar!


SGR burst affects EarthSGR burst affects Earth On the night of August 27, 1998 Earth's On the night of August 27, 1998 Earth's

upper atmosphere was bathed briefly by upper atmosphere was bathed briefly by an invisible burst of gamma- and X-ray an invisible burst of gamma- and X-ray radiation. This pulse - the most powerful radiation. This pulse - the most powerful to strike Earth from beyond the solar to strike Earth from beyond the solar system ever detected - had a significant system ever detected - had a significant effect on Earth's upper atmosphere, effect on Earth's upper atmosphere, report Stanford researchers. It is the report Stanford researchers. It is the first time that a significant change in first time that a significant change in Earth's environment has been traced to Earth's environment has been traced to energy from a distant star. (from the energy from a distant star. (from the NASA press release)NASA press release)


Gamma Ray Burst PropertiesGamma Ray Burst Properties

Unknown magnetic fieldUnknown magnetic field No repeatable periods seen in burstsNo repeatable periods seen in bursts No orbital periods seen – not in binariesNo orbital periods seen – not in binaries Thousands of bursts seen to date – no Thousands of bursts seen to date – no

repetitions from same locationrepetitions from same location Isotropic distributionIsotropic distribution Afterglows have detectable redshifts Afterglows have detectable redshifts

which indicate GRBs are at cosmological which indicate GRBs are at cosmological distances (i.e., far outside our galaxy)distances (i.e., far outside our galaxy)

LL = 10= 105252 - 10 - 105353 erg/s at peak of bursts erg/s at peak of bursts

A cataclysmic event of unknown originA cataclysmic event of unknown origin


The first Gamma-ray BurstThe first Gamma-ray Burst

Discovered in 1967 while looking for nuclear test explosions - a 30+ year old Discovered in 1967 while looking for nuclear test explosions - a 30+ year old mystery!mystery!

Vela satellite


Compton Gamma Ray Compton Gamma Ray ObservatoryObservatory

• Eight instruments on corners of spacecraft• NaI scintillators

BATSE


CGRO/BATSE Gamma-ray Burst CGRO/BATSE Gamma-ray Burst SkySky

Once a day, somewhere in the UniverseOnce a day, somewhere in the Universe


The GRB GalleryThe GRB Gallery

When you’ve seen one gamma-ray burst, you’ve seen….one gamma-ray burst!!


Near or Far?Near or Far?

Isotropic distribution implications:

Silly or not, the only way to be sure was to findthe afterglow.

Very close: within a few parsecs of the Sun

Very far: huge, cosmological distances

Sort of close: out in the halo of the Milky Way

Why no faint bursts?

What could produce such a vast amount of energy?

A comet hitting a neutron star fits the bill


Breakthrough!Breakthrough!

In 1997, BeppoSAX detects X-rays from a GRBafterglow for the first time, 8 hours after burst


The View From Hubble/STIS The View From Hubble/STIS

7 months 7 months laterlater


On a clear day, you really On a clear day, you really cancan see forever see forever

990123 reached 9th magnitude for a few moments!

First optical GRB afterglow detected simultaneously


The Supernova ConnectionThe Supernova Connection

GRB011121Afterglow faded like supernova

Data showed presence of gas like a stellar wind

Indicates some sort of supernova and not a NS/NS merger


HypernovaHypernova

A billion trillion times the power from the SunA billion trillion times the power from the Sun The end of the life of a star that had 100 times the mass of our Sun

movie


Iron lines in GRB 991216Iron lines in GRB 991216

Chandra observations show link to Chandra observations show link to hypernova model when hot iron-filled hypernova model when hot iron-filled gas is detected from GRB 991216gas is detected from GRB 991216

Iron is a signature of a supernova, as it is made in the cores of stars, and released in supernova explosions


Catastrophic MergersCatastrophic Mergers

Death spiral of 2 neutron stars or black holesDeath spiral of 2 neutron stars or black holes


Which model is right?Which model is right?

The data seem to indicate two kinds of GRBs

• Those with burst durations less than 2 seconds• Those with burst durations more than 2 seconds

Short bursts have no detectable afterglows so far as predicted by the NS/NS merger model

Long bursts are sometimes associated with supernovae, and all the afterglows seen so faras predicted by the hypernova merger model


Gamma-ray BurstsGamma-ray Bursts

Either way you Either way you look at it – look at it – hypernova or hypernova or merger modelmerger model

GRBs signal the GRBs signal the birth of a black birth of a black hole!hole!


Gamma-ray BurstsGamma-ray Bursts

Or maybe Or maybe the death the death of life on of life on Earth?Earth?

No, gamma-ray bursts did not kill the dinosaurs!


How to study Gamma rays?How to study Gamma rays?

Absorbed by the Earth’s Absorbed by the Earth’s atmosphereatmosphere

Use rockets, balloons or Use rockets, balloons or satellites satellites

Can’t image or focus gamma Can’t image or focus gamma rays rays

Special detectors: crystals, Special detectors: crystals, silicon-stripssilicon-strips

GLAST balloon

test


HETE-2HETE-2

Launched on 10/9/2000Launched on 10/9/2000 Operational and finding about 2 Operational and finding about 2

bursts per monthbursts per month


Swift MissionSwift Mission

Burst Alert Burst Alert Telescope (BAT)Telescope (BAT)

Ultraviolet/Ultraviolet/Optical Optical Telescope Telescope (UVOT)(UVOT)

X-ray Telescope X-ray Telescope (XRT)(XRT)

To be launched in 2004


Swift MissionSwift Mission

Will study GRBs with “swift” responseWill study GRBs with “swift” response Survey of “hard” X-ray skySurvey of “hard” X-ray sky To be launched in 2003To be launched in 2003 Nominal 3-year lifetimeNominal 3-year lifetime Will see ~150 GRBs per yearWill see ~150 GRBs per year


Gamma-ray Large Area Space Gamma-ray Large Area Space TelescopeTelescope

GLAST Burst Monitor (GBM)

Large Area Telescope (LAT)


GLAST MissionGLAST Mission

First space-based collaboration between First space-based collaboration between astrophysics and particle physics astrophysics and particle physics communitiescommunities

Launch expected in 2006Launch expected in 2006 Expected duration 5-10 yearsExpected duration 5-10 years Over 3000 gamma-ray sources will be Over 3000 gamma-ray sources will be

seenseen


GLAST Burst Monitor (GBM)GLAST Burst Monitor (GBM)

PI Charles Meegan (NASA/MSFC)PI Charles Meegan (NASA/MSFC) US-German secondary instrumentUS-German secondary instrument 12 Sodium Iodide scintillators12 Sodium Iodide scintillators

Few keV to 1 MeVFew keV to 1 MeV Burst triggers and locationsBurst triggers and locations

2 bismuth germanate detectors2 bismuth germanate detectors 150 keV to 30 MeV150 keV to 30 MeV Overlap with LATOverlap with LAT

http://gammaray.msfc.nasa.gov/gbm/http://gammaray.msfc.nasa.gov/gbm/


Large Area Telescope (LAT)Large Area Telescope (LAT)

PI Peter Michelson (Stanford)PI Peter Michelson (Stanford) International Collaboration: USA NASA International Collaboration: USA NASA

and DoE, France, Italy, Japan, Sweden and DoE, France, Italy, Japan, Sweden

• LAT is a 4 x 4 array of towers

• Each tower is a pair conversion telescope with calorimeter

http://www-glast.stanford.edu


Pair Conversion TelescopePair Conversion Telescope


LAT SchematicLAT Schematic

Tiled Tiled AnticoincidenAnticoincidence Shieldce Shield

Silicon strip Silicon strip detectors detectors interleaved interleaved with Tungsten with Tungsten converterconverter

Cesium Iodide Cesium Iodide hodoscopic hodoscopic calorimetercalorimeter


GLAST videoGLAST video A public outreach product from the A public outreach product from the

GLAST Education and Public GLAST Education and Public Outreach groupOutreach group


Web Resources :Web Resources :

GLAST E/PO web site GLAST E/PO web site http://glast.sonoma.eduhttp://glast.sonoma.edu Swift E/PO web site Swift E/PO web site http://swift.sonoma.eduhttp://swift.sonoma.edu Imagine the Universe! Imagine the Universe! http://imagine.gsfc.nasa.govhttp://imagine.gsfc.nasa.gov Science at NASA’s Marshall Space Flight Center Science at NASA’s Marshall Space Flight Center http://science.nasa.govhttp://science.nasa.gov John Blondin’s accretion simulations John Blondin’s accretion simulations http://www.physics.ncsu

.edu/people/faculty

http://science.msfc.nasa.govhttp://science.msfc.nasa.gov


Web ResourcesWeb Resources

Robert Duncan’s magnetar page http://solomon.as.utexas.edu/~duncan/magnetar.html Chandra observatory http://chandra.harvard.edu

Jochen Greiner’s Gamma-ray bursts and SGR Summaries http://www.mpe.mpg.de/~jcg

HETE-2 mission http://space.mit.edu/HETE/

Compton Gamma Ray Observatory http://cossc.gsfc.nasa.gov/

10/21/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

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Transcript of 10/21/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...