Optical Astronomy: Towards the HST, VLT and Keck Era

Introduction & OverviewIntroduction & Overview

Chris O’DeaChris O’Dea

Acknowledgements: Marc Postman, Jeff Valenti, & Bernard Rauscher

Aims for this lecture

Historical overview Historical overview

A brief history of optical astronomyA brief history of optical astronomy trends in aperture and detector sizetrends in aperture and detector size

CCD Detection CCD Detection Observing IssuesObserving Issues

Effect of the AtmosphereEffect of the Atmosphere Effect of the Space EnvironmentEffect of the Space Environment

Aims for this lecture II.

Optical Science Optical Science Pretty Pictures Pretty Pictures

– HSTHST

– VLTVLT The synergy between optical and radio (real astrophysics)The synergy between optical and radio (real astrophysics)

– The radio loud/quiet quasar transitionThe radio loud/quiet quasar transition

– Time scales for fueling and activity in radio galaxiesTime scales for fueling and activity in radio galaxies

Current `big’ issues in optical astronomyCurrent `big’ issues in optical astronomy

Atmospheric Transmission (300-1100 nm)

History

Pre-history: mismatch between solar and lunar cycles required Pre-history: mismatch between solar and lunar cycles required astronomical observations to calibrate calendars and predict astronomical observations to calibrate calendars and predict times for natural and agricultural eventstimes for natural and agricultural events

Newgrange, Ireland 3500 BCNewgrange, Ireland 3500 BC Stonehenge, England 3000 BCStonehenge, England 3000 BC

First millenium BC – Greeks search forFirst millenium BC – Greeks search for Systematics of planetary motionSystematics of planetary motion Geometric model for planetary motion Geometric model for planetary motion

Ptolemy’s Almagest (AD 145) presented robust geometric Ptolemy’s Almagest (AD 145) presented robust geometric model of planetary motionmodel of planetary motion

1212thth century Islam- Need for more accurate measurements of century Islam- Need for more accurate measurements of positions led to first “observatories” – dedicated structures positions led to first “observatories” – dedicated structures housing large, fixed instruments.housing large, fixed instruments.

History

1575 Tycho Brahe’s Uraniborg – prototype of modern observatory1575 Tycho Brahe’s Uraniborg – prototype of modern observatory 1609 Galileo uses telescope for astronomy1609 Galileo uses telescope for astronomy

Features on the moonFeatures on the moon Sattelites of JupiterSattelites of Jupiter Stars remained unresolvedStars remained unresolved

Development of reflecting telescopes (enables larger collecting Development of reflecting telescopes (enables larger collecting areas)areas)

Gregory 1663, Newton 1668, Cassegrain 1672Gregory 1663, Newton 1668, Cassegrain 1672 Spectroscopy Spectroscopy

1817 Fraunhofer combines narrow slit, prism and telescope to make first 1817 Fraunhofer combines narrow slit, prism and telescope to make first spectrograph and discovers spectrum of the sunspectrograph and discovers spectrum of the sun

1859 Kirchoff shows that the solar spectrum reveals the chemical 1859 Kirchoff shows that the solar spectrum reveals the chemical compositioncomposition

History

PhotographyPhotography 1845 daguerreotype of sun – Focault & Fizeau1845 daguerreotype of sun – Focault & Fizeau 1870’s - Improvements led to photography of faint 1870’s - Improvements led to photography of faint

stars and nebulaestars and nebulae 1872 – Draper obtained photographic spectrum of 1872 – Draper obtained photographic spectrum of

VegaVega

1875-1900 Combination of Photography and 1875-1900 Combination of Photography and Spectroscopy led to a shift of astronomy from Spectroscopy led to a shift of astronomy from positional measurements to astrophysicspositional measurements to astrophysics

History

1970’s 4-m class telescopes become common1970’s 4-m class telescopes become common 1980’s CCDs are developed1980’s CCDs are developed 1990 HST launched1990 HST launched 1990’s 10-m class telescopes become available1990’s 10-m class telescopes become available

Newgrange Megalithic Passage Tomb

Built ~3500 BC in County Meath, Ireland

On winter solstice sun shines down roof box and illuminates central 62-ft passage.

Passage is illuminated for 17 min after dawn Dec 19-23

Tycho Brahe’s Uraniborg

Built 1576-1580

Prototype of “modern” observatory

First “Big Science” – required 1% of Danish national budget!

Dedicated to precision positional measurements (one arcmin) – made possible advances by Copernicus and Kepler

Telescopes in TimeTelescopes in Time

1609Galileo 1.75”

1609Galileo 1.75”

1672Newton 1.5”

1672Newton 1.5”

1859: Clark 18.5”1859: Clark 18.5”1858: Lassell 48”

First “Large” Reflector1858: Lassell 48”

First “Large” Reflector

1917 Hooker 100””1917 Hooker 100”” 1948 Hale 200”1948 Hale 200”

1897 Yerkes 40”Largest Refractor

1897 Yerkes 40”Largest Refractor

Edwin Hubble

Hubble & Humason 1931, ApJ, 74, 43

H~560 km/sec/Mpc

0

50

100

150

200

250

300

350

400

450

1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

Year

Pri

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GalileoGalileo NewtonNewton

KeckKeck

Aperture vs Time

0

2

4

6

8

10Te

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Ape

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The Biggest Telescopes TodayThe Biggest Telescopes Today

HST

Size Distribution of the 46 largest optical telescopes

Size Distribution of the 46 largest optical telescopes

Luppino, 1998

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

# P

ixel

s

UH4k2

Macho8k2

NOAO4k2

MOCAM4k2

UH8K2

BTC4k2

EROS8k2 NOAO8k2

DEIMOS8k2

QUEST8k2

MDM8k2

MAGNUM8k2

CTIO8k2

ESO8k2

DMT38k2

WFHRI36k2

CFH_MEGA18k2

MMT_MEGA18k2

OMEGA16k2

SDSS10kx12k UW12kx16kCFH8kx12k

2kx2k4kx4k8kx8k

18k x 18k

2k2

CCD Camera Development for Ground Applications:

8k x 8k

4k x 4k

2k x 2k

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1990 1995 2000 2005 2010

Year

# P

ixel

s

WFPC14x0.8k2

WFPC24x0.8k2

STIS 1kx1k

ACS 4kx4k WF3 4kx4k

Fame 24 2kx4k

Kepler 21x2k2

GAIA136x2k2

SNAP 250x2k2

GEST 60 3kx6k

CCD Camera Development for Space Applications:

18k x 18k

8k x 8k

4k x 4k

2k x 2k

Astronomy at the end of the 20th Century

Questions about the universe have become progressively more Questions about the universe have become progressively more sophisticatedsophisticated From From “Are there other galaxies? (ca. 1920)”“Are there other galaxies? (ca. 1920)” to to “What is the origin of “What is the origin of

structure in the universe?”structure in the universe?” From From “How many planets in our solar system?“How many planets in our solar system? (Pluto discovered 1930)” (Pluto discovered 1930)”

to to “How many extra-solar planetary systems lie within 100 light years of “How many extra-solar planetary systems lie within 100 light years of the sun?”the sun?” … and are any inhabited? … and are any inhabited?

The basics of cosmology (age & density of universe), detailed maps of The basics of cosmology (age & density of universe), detailed maps of the nearby galaxy dist’n, a basic theory of stellar evolution, and a the nearby galaxy dist’n, a basic theory of stellar evolution, and a census of the stars in the solar neighborhood exist (or will exist within census of the stars in the solar neighborhood exist (or will exist within 5 years).5 years).

Astronomers today rely heavily on joint observations from ground & Astronomers today rely heavily on joint observations from ground & space and data spanning large regions of the electromagnetic space and data spanning large regions of the electromagnetic spectrum.spectrum.

Questions about the universe have become progressively more Questions about the universe have become progressively more sophisticatedsophisticated From From “Are there other galaxies? (ca. 1920)”“Are there other galaxies? (ca. 1920)” to to “What is the origin of “What is the origin of

structure in the universe?”structure in the universe?” From From “How many planets in our solar system?“How many planets in our solar system? (Pluto discovered 1930)” (Pluto discovered 1930)”

to to “How many extra-solar planetary systems lie within 100 light years of “How many extra-solar planetary systems lie within 100 light years of the sun?”the sun?” … and are any inhabited? … and are any inhabited?

The basics of cosmology (age & density of universe), detailed maps of The basics of cosmology (age & density of universe), detailed maps of the nearby galaxy dist’n, a basic theory of stellar evolution, and a the nearby galaxy dist’n, a basic theory of stellar evolution, and a census of the stars in the solar neighborhood exist (or will exist within census of the stars in the solar neighborhood exist (or will exist within 5 years).5 years).

Astronomers today rely heavily on joint observations from ground & Astronomers today rely heavily on joint observations from ground & space and data spanning large regions of the electromagnetic space and data spanning large regions of the electromagnetic spectrum.spectrum.

CCD Detection

• CCDs are arrays of Metal Oxide Semiconductor (MOS) capacitors CCDs are arrays of Metal Oxide Semiconductor (MOS) capacitors separated by channel stops (implanted potential barriers).separated by channel stops (implanted potential barriers).

• Application of positive voltage repels majority carriers (holes) from Application of positive voltage repels majority carriers (holes) from region underneath oxide layer, forming a potential well for electrons.region underneath oxide layer, forming a potential well for electrons.

• A photon produces an electron-hole pair: the hole is swept out of A photon produces an electron-hole pair: the hole is swept out of depletion region and electron is attracted to the positive electrode.depletion region and electron is attracted to the positive electrode.

• Photoexcited charge collects in “depletion region” at PN junction.Photoexcited charge collects in “depletion region” at PN junction.• Collected charge is shifted to amplifier (CCD) or sensed in situ (IR).Collected charge is shifted to amplifier (CCD) or sensed in situ (IR).

Metal Electrode

Depletion Region

Silicon Dioxide

Silicon Substrate

+

MOS Capacitor:

Structure of a 3-Phase CCD

Consider a 3-phase CCD.

•Columns are separated by non-conducting channel stops.

•Rows are defined by electrostatic potential.

•Charge is physically moved within the detector during readout.

CCD Vertical Structure

In the vertical direction, one sees a PN junction and In the vertical direction, one sees a PN junction and control electrodes. control electrodes.

Depletion regions form under both the metal gate and at Depletion regions form under both the metal gate and at the PN junction.the PN junction.

Charge is collected where these depletion regions overlap.Charge is collected where these depletion regions overlap.

Charge moves in a CCD

By changing electrode voltages, charge can be moved to By changing electrode voltages, charge can be moved to the output amplifier.the output amplifier.

This process is called charge transfer.This process is called charge transfer. In an IR array, this does not happen. Charge is sensed in In an IR array, this does not happen. Charge is sensed in

place.place.

Packet of Q electrons is transferred through the outputPacket of Q electrons is transferred through the output

gate onto a storage capacitor, producing a voltage V=Q/C.gate onto a storage capacitor, producing a voltage V=Q/C.

CCDReadoutAmplifier

CCD Readout Amplifier:

The Atmosphere

Atmospheric absorption versus airmass

The amount of absorbed radiation depends upon The amount of absorbed radiation depends upon the number of absorbers along the line of sightthe number of absorbers along the line of sight

Atmosphere

..

,,10 5.2/,0

tcoefficienextinctionatmiswhere

AMmagII mag

AM=1AM=2

Particle number densities (n) for most absorbers fall off Particle number densities (n) for most absorbers fall off rapidly with increasing altitude.rapidly with increasing altitude.

xx0,H0,H2200 km, km, xx0,CO0,CO22 km, km, xx0,O0,O33

kmkm

So, 95% of atmospheric water vapor is below the altitude So, 95% of atmospheric water vapor is below the altitude of Mauna Kea.of Mauna Kea.

Atmospheric absorption versus altitude

II0,e ,where is optical depth,

ndx e x / x 0 dx

Atmospheric Turbulence A diffraction-limited point spread function (PSF) has a full-width A diffraction-limited point spread function (PSF) has a full-width

at half-maximum (FWHM) of:at half-maximum (FWHM) of:

In reality, atmospheric turbulence smears the image:In reality, atmospheric turbulence smears the image:

At Mauna Kea, rAt Mauna Kea, r00=0.2 m at 0.5 =0.2 m at 0.5 m.m. ““Isoplanatic patch” is area on sky over which phase is relatively Isoplanatic patch” is area on sky over which phase is relatively

constant.constant.

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Atmospheric Turbulence

Lick 3-m Figer 1995PhD Thesis

Keck I 10-m Serabyn, Shupe, & FigerNature 1998, 394, 448

HST/NICMOS 2.4-m Figer et al. 1999ApJ. 525, 750

1.4seeing 0.5seeing noseeing!

Adaptive Optics: “Eye Glasses” for Ground-based TelescopesAdaptive Optics: “Eye Glasses” for Ground-based Telescopes

Laser Guide StarLaser Guide Star

WaveFront

Sensor

WaveFront

SensorAdjustMirrorShape

AdjustMirrorShape

Adaptive Optics: “Eye Glasses” for Ground-based Telescopes

Where does NGST win?Where does NGST win?

NGST should perform better than current NGST should perform better than current 10m class ground-based telescopes.10m class ground-based telescopes.

In the mid-IR range (wavelengths In the mid-IR range (wavelengths 3 3 ), ), NGST will produce better quality (higher NGST will produce better quality (higher S/N) images and spectra than a 50m AO S/N) images and spectra than a 50m AO corrected ground-based telescope. corrected ground-based telescope.

For surveying large fields of view – AO For surveying large fields of view – AO only works over a small field of view.only works over a small field of view.

Sky is much darker in space in NGST’s Sky is much darker in space in NGST’s wavelength range – better faint object wavelength range – better faint object detection.detection.

NGST should perform better than current NGST should perform better than current 10m class ground-based telescopes.10m class ground-based telescopes.

In the mid-IR range (wavelengths In the mid-IR range (wavelengths 3 3 ), ), NGST will produce better quality (higher NGST will produce better quality (higher S/N) images and spectra than a 50m AO S/N) images and spectra than a 50m AO corrected ground-based telescope. corrected ground-based telescope.

For surveying large fields of view – AO For surveying large fields of view – AO only works over a small field of view.only works over a small field of view.

Sky is much darker in space in NGST’s Sky is much darker in space in NGST’s wavelength range – better faint object wavelength range – better faint object detection.detection.

Observing in Space

Deployed 25 Apr 1990Deployed 25 Apr 1990 Mass: 11600 kgMass: 11600 kg Length: 13.1 mLength: 13.1 m Primary diameter: 2.4 mPrimary diameter: 2.4 m Secondary: 0.34 mSecondary: 0.34 m f/24 Ritchey-Chrétienf/24 Ritchey-Chrétien 28 arcmin field-of-view28 arcmin field-of-view 0.11 0.11 m < m < < 3 < 3 mm 0.043 arcsec FWHM at 5000 0.043 arcsec FWHM at 5000

ÅÅ

HST Facts

Height = 590 kmHeight = 590 km Orbital period = 96.6 minutesOrbital period = 96.6 minutes Precessional period = 56 daysPrecessional period = 56 days Inclination = 28.5Inclination = 28.5°° Continuous viewing zones (CVZ) at Continuous viewing zones (CVZ) at ±61.5°±61.5°

HST Orbit:

Space Environment:

Magnetic Flux Tubes:

Radiation damageRadiation damage limits the science lifetime of a CCD limits the science lifetime of a CCD Ionization damage - flat band shiftsIonization damage - flat band shifts Bulk damageBulk damage

– Displacement of Si atoms in lattice produces trapsDisplacement of Si atoms in lattice produces traps– Hot pixels created by electrons from silicon Hot pixels created by electrons from silicon

valence band jump to trapping centers and valence band jump to trapping centers and generate high dark currentgenerate high dark current

AnnealingAnnealing once a month to mitigate hot pixel accumulation. once a month to mitigate hot pixel accumulation. WFPC2 is warmed to +20WFPC2 is warmed to +20o o CC STIS CCD is warmed -15STIS CCD is warmed -15o o CC 80% of new hot pixels (>0.1 electron sec 80% of new hot pixels (>0.1 electron sec –1–1 pix pix –1–1 ) fixed ) fixed

ACS CCD10 year

dose

CCD Radiation Damage:

Courtesy R. Gilliland (STScI)

NGC 6752, 8 20s, ‘D’ amp at the top

SITe 1024 1024 CCD thinned backside

Losses Transferring Charge

Degradation of Charge Transfer Efficiency

Paral

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Optical Science

Pretty Pictures

Astrophysics

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Hubble Deep Field

There is a Synergy between High Resolution Optical and Radio ObservationsThere is a Synergy between High Resolution Optical and Radio Observations

The Radio Loud/Quiet Transition

Sanders & Mirabel 1996, ARAA, 34, 749

Overall SED is similar for RL and RQ quasars.

Why the difference in radio power?

Smooth Distribution in Radio Loudness

FIRST quasars. Solid line = all quasars, hatched region = newly discovered quasars . Traditionally, radio loud objects have log R ~3-4. Brinkmann etal 2000, A&A, 356, 445

Unimodal Distribution of Quasar Radio Luminosity

5 GHz luminosity of FIRST Bright Quasar Survey II. White etal. 2000, ApJS, 126, 133

Radio Luminosity – Optical Line Correlation.

There is a strong correlation between radio luminosity and optical emission line luminosity for both RL and RQ objects. (see also Baum & Heckman 1989)

Xu etal 1999, AJ, 118, 1169

Emission Lines are Powered by Accretion Disk Luminosity.

There is a strong correlation between X-ray luminosity and optical emission line luminosity for both RL and RQ objects.

Xu etal 1999, AJ, 118, 1169

The AGN Paradigm

Annotated by M. Voit Annotated by M. Voit

What Causes the RL – RQ Transition?

Earlier data indicated a Bi-modal distribution of radio Earlier data indicated a Bi-modal distribution of radio

loudness suggesting that the transition was very abrupt. loudness suggesting that the transition was very abrupt. New data suggests a continuous distribution of radio New data suggests a continuous distribution of radio loudness. Thus, there is a more gradual transition. loudness. Thus, there is a more gradual transition.

Previously it was thought that there was a correlation with Previously it was thought that there was a correlation with host galaxy type – I.e., RQs are in Spirals and RLs in host galaxy type – I.e., RQs are in Spirals and RLs in Elliptical hosts. New data suggests that Ellipticals host Elliptical hosts. New data suggests that Ellipticals host both RQ and RL quasars but only those with optically both RQ and RL quasars but only those with optically luminous nuclei. luminous nuclei.

Quasar Host Galaxy Observations

Sample rest frame optical avoiding bright emission lines.Sample rest frame optical avoiding bright emission lines. Match samples in optical luminosity at different z. Match samples in optical luminosity at different z. Kukula et al. Kukula et al.

2001, MNRAS, 326 15332001, MNRAS, 326 1533

Properties of the Host Galaxies

The surface The surface brightness profiles are brightness profiles are well fit by a rwell fit by a r¼ ¼ law; law; I.e. the host galaxies I.e. the host galaxies are bulge dominated.are bulge dominated.

Dunlop etal 2001, astroph

Properties of the Host Galaxies

The more luminous nuclei The more luminous nuclei live in galaxies which are live in galaxies which are more bulge dominated.more bulge dominated.

Disk-dominated hosts Disk-dominated hosts become increasingly rare become increasingly rare with increasing nuclear with increasing nuclear power.power.

Relative contribution of the bulge to the total luminosity of the host galaxy. RLQs are open, RQQs are filled circles, * are X-ray selected AGN from Schade etal (2000). Dunlop etal 2001, astroph

BH Mass vs. Galaxy Bulge Mass

There is a relationship between BH mass and bulge luminosity. And an even tighter relationship with the bulge velocity dispersion. M(BH) ~ 10-3 M(Bulge). Ferrarese & Merritt 2000, ApJ, 539, L9

Consistency Between Different Methods BH Mass vs bulge magnitude relation is similar for both active and quiescent galaxies.

BH Mass vs bulge magnitude for quiescent galaxies, Seyferts and nearby quasars. Size of symbol for AGN is proportional to the Hβ FWHM. Merritt & Ferrarese 2001, astro-ph/0107134

BH Masses BH Masses tend to be BH Masses tend to be

high in these luminous high in these luminous quasars.quasars.

Estimates of BH mass from Estimates of BH mass from HHββ line widths and host line widths and host spheroid luminosity are in spheroid luminosity are in rough agreement. rough agreement.

RLQs tend to have higher RLQs tend to have higher BH mass than RQQs.BH mass than RQQs.

Assumes MAssumes Mbhbh = 0.0025 M = 0.0025 Msphsph

Comparison between BH masses estimated from the host galaxy spheriod luminosity and the Hβ line-width by McLure & Dunlop (2001). The shaded area marks BH masses greater then 109 solar masses. RLQs are open, RQQs are filled circles. Dunlop etal 2001, astroph

What Fraction of Eddington Luminosity?

RQQ and RLQs are RQQ and RLQs are radiating at 1-10% of radiating at 1-10% of their Eddington their Eddington luminosity. luminosity.

Observed nuclear absolute magnitude vs that expected if the BH is emitting at the Eddington luminosity. RLQs are open, RQQs are filled circles. Solid, dashed, and dot-dashed are 100%, 10% and 1% of Eddington luminosity. Dunlop etal 2001, astroph

The Paradigm Shift

Earlier data indicated a Bi-modal distribution of radio Earlier data indicated a Bi-modal distribution of radio loudness suggesting that the transition was very abrupt. loudness suggesting that the transition was very abrupt. New data suggests a continuous distribution of radio New data suggests a continuous distribution of radio loudness. Thus, there is a more gradual transition. loudness. Thus, there is a more gradual transition.

Previously it was thought that there was a correlation with Previously it was thought that there was a correlation with host galaxy type – I.e., RQs are in Spirals and RLs in host galaxy type – I.e., RQs are in Spirals and RLs in Elliptical hosts. New data suggests that Ellipticals host Elliptical hosts. New data suggests that Ellipticals host both RQ and RL quasars but only those with optically both RQ and RL quasars but only those with optically luminous nuclei. luminous nuclei.

This is consistent with a correlation between optically This is consistent with a correlation between optically luminous nuclei and massive BHs and between BH mass luminous nuclei and massive BHs and between BH mass and host galaxy bulge mass. and host galaxy bulge mass.

Is it BH Spin ?

Possibilities includePossibilities include BH Mass (but both RQs and RLs live in big bulges BH Mass (but both RQs and RLs live in big bulges

and thus have high BH Mass)and thus have high BH Mass) Mass accretion rate (but RQs and RLs have similar Mass accretion rate (but RQs and RLs have similar

optical luminosities)optical luminosities) BH SpinBH Spin

Time Scales for Gas Transport, Fueling, and AGN Activity

Double-Doubles -- “Born-again” Radio Sources

5-10% of > 1 Mpc radio 5-10% of > 1 Mpc radio sources show double-sources show double-double structure.double structure.

Working hypothesis: the Working hypothesis: the radio galaxy turned off radio galaxy turned off and then turned back on --and then turned back on --creating a new double creating a new double propagating outwards propagating outwards amidst the relic of the amidst the relic of the previous activity.previous activity.

Schoenmakers etal (2000)Schoenmakers etal (2000)

Schematic of Supersonic Jet Model

Concept from Scheuer 1974, Blandford & Rees 1974. Illustration from Carvalho & O’Dea 2001. Concept from Scheuer 1974, Blandford & Rees 1974. Illustration from Carvalho & O’Dea 2001.

Probing Time Scales of Activity

The double-doubles allow us to probe the timescale of recurrent activity and the nature of the fuelling/triggering of the activity.

Selection effects will limit the time scales which can be detected in the double-doubles

If the source tuns off for < 106 yr the effects on the larger source may not be noticable, and the younger source may not be resolved from the core.

If the source turns off for > 108 yr, the larger source will fade.

3C236 - 4 Mpc Radio Source

The largest The largest radio galaxy radio galaxy known. known.

WSRT 92 cm image WSRT 92 cm image (55”x96”) Mack etal. (55”x96”) Mack etal. 1997) overlayed on 1997) overlayed on

DSS imageDSS image..

The Inner 2 Kpc Double

Global VLBI 1.66 GHz image (Schilizzi etal 2001)

superposed on HST WFPC2 V band image

At z=0.1, and Ho=75,

1 arcsec = 1.7 kpc

O’Dea etal. 2001, AJ, 121, 1915

Inner 2 kpc double is well aligned with outer 4 Mpc double

The Host Galaxy (in color)

NoteNote• dust lane along major axisdust lane along major axis• tilted inner disktilted inner disk• blue knots along innerblue knots along inner

edge of dust laneedge of dust lane

3-color image. 3-color image.

STIS Near-UV MAMA STIS Near-UV MAMA (F25SRF2 2300(F25SRF2 2300Å) 1440sÅ) 1440s

WFPC2 F555W (V) 600sWFPC2 F555W (V) 600s

WFPC2 F702W (R) 560s WFPC2 F702W (R) 560s

O’Dea etal. 2001, AJ, 121, 1915O’Dea etal. 2001, AJ, 121, 1915

STIS Near-UV Image

Note the 4 very blue regions in an arc along Note the 4 very blue regions in an arc along the inner edge of the dust lane ~0.5” the inner edge of the dust lane ~0.5” (800 pc) from the nucleus, and (800 pc) from the nucleus, and perpendicular to the radio source axis.perpendicular to the radio source axis.

Regions are resolved with sizes ~0.3” (500 Regions are resolved with sizes ~0.3” (500 pc)pc)

No strong emission lines in the F25SRF2 No strong emission lines in the F25SRF2 filterfilter

Most likely to be due to relatively young Most likely to be due to relatively young star formationstar formation

Bruzual-Charlot population synthesis Bruzual-Charlot population synthesis models are consistent with ages models are consistent with ages 5-10 5-10 Myr for knots 1,3 and ~100 Myr for Myr for knots 1,3 and ~100 Myr for knots 2,4knots 2,4

STIS NUV image with global VLBI image STIS NUV image with global VLBI image (Schilizzi etal 2001) superposed. (Schilizzi etal 2001) superposed.

O’Dea etal. 2001, AJ, 121, 1915O’Dea etal. 2001, AJ, 121, 1915

Ages Estimated via Comparison with Stellar Population Models

(Top) UV-V color as a function (Top) UV-V color as a function of time for Bruzual-Charlot of time for Bruzual-Charlot models with both constant models with both constant star formation and an star formation and an instantaneous burst.instantaneous burst.

(Bottom) Evolution in color-(Bottom) Evolution in color-color space of 3 models. color space of 3 models. Plotted are the colors of the 4 Plotted are the colors of the 4 knots, the nucleus, and the knots, the nucleus, and the older population in the host older population in the host galaxy.galaxy.

Knots 1, 3 are consistent with 5-Knots 1, 3 are consistent with 5-10 Myr, and knots 2, 4 with 10 Myr, and knots 2, 4 with ~100 Myr.~100 Myr.

O’Dea etal. 2001, AJ, 121, 1915O’Dea etal. 2001, AJ, 121, 1915

Star Formation Properties

Time Scales

Dynamical Ages:

Large radio source: t~7.8x108 (v/0.01c) yr (comparable to the age of the oldest blue knots)

Small radio source: t~3.2x105 (v/0.01c) yr (much younger than the youngest blue knots)

Dynamical time scale of the disk on the few hundred pc scale t~107 yr

Alignments and the Bardeen-Petterson effect

The small and large scale radio source are aligned to within about 10 deg.

The radio sources are aligned to within a few degrees of perpendicular to the “inner" (1 kpc) dust disk but are poorly aligned with the perpendicular to the larger dust lane.

The Bardeen-Petterson effect will cause the black hole to swing its rotation axis into alignment with the rotation axis of the disk of gas (on scales of hundreds to thousands of Schwarzschild radii) which is feeding it; and conversely will keep the spin axis of the inner disk aligned with the BH spin (e.g., Bardeen & Petterson 1975; Rees 1978)

The combination of the long term stability of the jet ejection axis and the alignment of the jets with the inferred rotation axis of the inner kpc-scale dust disk suggests that the orientation of the inner dust disk has also been stable over the lifetime of the radio source.

This also implies that the outer misaligned dust lane (which presumably feeds the disk) settles into the same preferred plane as the disk.

The Scenario

The small and large radio sources are due to two different events of mass infall.

Spectral aging estimates in the hot spotes of the large source imply the radio source may have turned off for ~ 107 yr in between the two events.

The difference in the ages of the young and old star formation regions also implies two different triggers.

Implications

The two episodes of radio activity and the two The two episodes of radio activity and the two episodes of star formation are due to non-steady episodes of star formation are due to non-steady transport of gas in the disk. transport of gas in the disk.

If the young radio source and the young starburst If the young radio source and the young starburst (knots 1,3) are related by the same mass transport (knots 1,3) are related by the same mass transport event, the gas must be transported from the event, the gas must be transported from the hundreds of pc scale to the sub-pc scale on the hundreds of pc scale to the sub-pc scale on the dynamical time scale.dynamical time scale.

The Current Big Issues

Current `Big’ Issues for Optical Astronomy

Planet Formation & EvolutionPlanet Formation & Evolution When, where, & how frequently do planets form?When, where, & how frequently do planets form? How important is dynamical evolution in planet How important is dynamical evolution in planet

formation and consequent habitability?formation and consequent habitability? Answers will require powerful (high S/N, high res.) Answers will require powerful (high S/N, high res.)

spectroscopic observations as 1 AU spectroscopic observations as 1 AU 0.002” at Orion 0.002” at Orion

Planet Formation & EvolutionPlanet Formation & Evolution When, where, & how frequently do planets form?When, where, & how frequently do planets form? How important is dynamical evolution in planet How important is dynamical evolution in planet

formation and consequent habitability?formation and consequent habitability? Answers will require powerful (high S/N, high res.) Answers will require powerful (high S/N, high res.)

spectroscopic observations as 1 AU spectroscopic observations as 1 AU 0.002” at Orion 0.002” at Orion

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Current ‘Big’ Issues for Optical Astronomy

Star Formation & EvolutionStar Formation & Evolution Must have a more predictive and comprehensive theory Must have a more predictive and comprehensive theory

for star formation & evolutionfor star formation & evolution Will require studies of stellar systems in hundreds of Will require studies of stellar systems in hundreds of

other galaxies at (angular & spectral) resolutions other galaxies at (angular & spectral) resolutions comparable with the work done in our own Galaxycomparable with the work done in our own Galaxy

Star Formation & EvolutionStar Formation & Evolution Must have a more predictive and comprehensive theory Must have a more predictive and comprehensive theory

for star formation & evolutionfor star formation & evolution Will require studies of stellar systems in hundreds of Will require studies of stellar systems in hundreds of

other galaxies at (angular & spectral) resolutions other galaxies at (angular & spectral) resolutions comparable with the work done in our own Galaxycomparable with the work done in our own Galaxy

Current ‘Big’ Issues in Optical Astronomy

Galaxy Formation & EvolutionGalaxy Formation & Evolution When do the first stars and galaxies form?When do the first stars and galaxies form? What processes trigger this formation and how do they What processes trigger this formation and how do they

affect a galaxy’s evolution?affect a galaxy’s evolution? Develop a predictive theory of galaxy formation and evolutionDevelop a predictive theory of galaxy formation and evolution

Galaxy Formation & EvolutionGalaxy Formation & Evolution When do the first stars and galaxies form?When do the first stars and galaxies form? What processes trigger this formation and how do they What processes trigger this formation and how do they

affect a galaxy’s evolution?affect a galaxy’s evolution? Develop a predictive theory of galaxy formation and evolutionDevelop a predictive theory of galaxy formation and evolution

HST Deep FieldHST Deep Field TheoryTheory

Current ‘Big’ Issues for Optical Astronomy

Large-scale StructureLarge-scale Structure How are (proto) galaxies & clusters How are (proto) galaxies & clusters

distributed at when universe was only 25% of distributed at when universe was only 25% of it’s current age (z > 2)?it’s current age (z > 2)?

How do the distributions depend on the How do the distributions depend on the galaxy’s mass, morphology, or star formation galaxy’s mass, morphology, or star formation rate in these early epochs?rate in these early epochs?

How does structure evolve from the very How does structure evolve from the very smooth pattern when universe was only a few smooth pattern when universe was only a few 100,000 years old (z ~ 1000) to the highly 100,000 years old (z ~ 1000) to the highly clumped and coherent pattern seen since last clumped and coherent pattern seen since last 6 billion years or so (z < 1)?6 billion years or so (z < 1)?

Answers will require large area telescope(s) Answers will require large area telescope(s) with large FOV and (moderate resolution) with large FOV and (moderate resolution) spectrographspectrograph

Large-scale StructureLarge-scale Structure How are (proto) galaxies & clusters How are (proto) galaxies & clusters

distributed at when universe was only 25% of distributed at when universe was only 25% of it’s current age (z > 2)?it’s current age (z > 2)?

How do the distributions depend on the How do the distributions depend on the galaxy’s mass, morphology, or star formation galaxy’s mass, morphology, or star formation rate in these early epochs?rate in these early epochs?

How does structure evolve from the very How does structure evolve from the very smooth pattern when universe was only a few smooth pattern when universe was only a few 100,000 years old (z ~ 1000) to the highly 100,000 years old (z ~ 1000) to the highly clumped and coherent pattern seen since last clumped and coherent pattern seen since last 6 billion years or so (z < 1)?6 billion years or so (z < 1)?

Answers will require large area telescope(s) Answers will require large area telescope(s) with large FOV and (moderate resolution) with large FOV and (moderate resolution) spectrographspectrograph

The End