Simulating the spectra of Quasars: A simple disk-wind model for BALQSOs

School of Physics & Astronomy

Simulating the spectra of Quasars:A simple disk-wind model for BALQSOs

Nick Higginbottom (Southampton University)Christian Knigge (Southampton University)Knox Long (STScI) Stuart Sim (Queens University - Belfast)James Matthews (Southampton University)

Naples 21st May 2013

School of Physics & AstronomyOverview

• The problem – BALQSOs, outflows and QSO unification

• A benchmark disk-wind model• Physical state and synthetic spectra for

benchmark model• X-ray results and sensitivity• Summary and the future

Nick Higginbottom Modelling the spectra of (BAL)QSOs


Elvis (2000) Gibson+ (2009)

BALQSOs• Blue shifted absorption features imply outflows at

velocities of ≥ 0.1c (Weymann+ 1981)

• Continuum / emission features similar to other QSO types• Common underlying structure? • Disk-winds?

• BALQSO clearest indicator

Reichard+ (2003)


School of Physics & AstronomyBALQSOs – Evolution vs Orientation

• About 20% of the population of QSOs exhibit BAL properties (e.g. Knigge+ [2008] and Hewett & Foltz [2003])

• Evolution:• All QSOs spend 20% of the time as BALs

• Orientation• BAL Outflows cover 20% of viewing angles

• Our Aims: • Turn qualitative models into quantitative predictions using Monte Carlo

radiative transfer code - PYTHON (Long & Knigge [2003], Higginbottom et al. [2013 in prep])

• Produce something that looks like a BALQSO from some directions• Can such models look like other types of QSO from other directions?• Can the X-ray properties of such models be made to agree with

observations?Nick Higginbottom Modelling the spectra of (BAL)QSOs

School of Physics & AstronomyPYTHON – a 3D ionization and radiative

transfer code.• Arbitrary 3D wind geometry• Kinematic models• Hydrodynamic simulations

• Monte Carlo radiative transfer• Fast ionization calculations

• Modified Saha approximation• Thermal / Radiative equilibrium

• heating/cooling: free free, line, Comptonphotoionzation, recombination


Validation of PYTHON (dots) vs CLOUDY (lines)

School of Physics & AstronomyA benchmark wind model

Geometry based on Shlosman and Vitello (1993)Nick Higginbottom Modelling the spectra of (BAL)QSOs

• INPUT SPECTRUMMBH = 109MMacc = 5Myr-1 Lx = 1043ergs s-1

• WIND PARAMETERSRmin = 300RGRmax = 600RGθmin = 70°θmax = 82°Mwind= 5Myr-1

V∞ = Vescape



Properties of benchmark model

School of Physics & AstronomyProperties of benchmark model

School of Physics & AstronomyPredicted Spectra – 40°


• (Weak) thermal / scattering emission lines• Slight continuum enhancement due to electron

scattering Continuum without windDisk-wind spectrum



• Sightline into wind cone• Strong BAL features

Continuum without windDisk-wind spectrumAttenuated continuum



• Sightline through base of wind• Emission lines appear brighter due to attenuated

continuum Continuum without windDisk-wind spectrumAttenuated continuum

School of Physics & AstronomyX-ray properties of benchmark

model

Benchmark model

Figure from Saez+ 2011


40

75

85

School of Physics & AstronomyIncreasing LX

1. Increasing X-ray luminosity destroys the BAL

Mass loss rate through wind

X-ray luminosity


Subplot scales

-3x109 velocity (cms-1) +3x109

flux



2. Increasing the mass loss rate gets it back!


X-ray luminosity


Subplot scales


flux

Increasing LX and Mwind



2. Increasing the mass loss rate gets it back!

3. For Lx = 2x1044ergs s-1 need Mwind=20Myr -1

4. Mwind=4Macc OK??


X-ray luminosity


Subplot scales


flux

Increasing LX and Mwind

.

..

School of Physics & AstronomyX-ray properties of high Lx Mwind

model Figure from Saez+ 2011


Benchmark modelObservable values for L2-10keV=2e44ergs s-1, 25 solar mass per year mass loss

40

75

85

8540

75

School of Physics & AstronomySummary and plans for the

future• We have produced a simple disk-wind BAL model

Higginbottom et al. (2013 in prep)

• Correct ionization state• Strong BAL features• X-ray weak• Weak line emission

• The next steps• Explore parameter space• Uniqueness? X-rays? Emission?

• Investigate hydro-models - Higginbottom, Proga et al. (2013 in prep)


Data from Proga & Kallman 04

School of Physics & AstronomyThanks!


School of Physics & AstronomyMaking CIV in the wind – lessons

learntPhotoionization absorption in the root of the wind

attenuates UV

School of Physics & AstronomyMaking CIV in the wind – lessons

learntEasier to make CIV with a larger BH:

School of Physics & AstronomyVarying X-rays

Fiducial model is X-ray weakInput αOX varies from -2.4 (pole on) to -1.8 (edge

on)Emergent αOX much lower due to X-ray absorption

in the wind for BAL sightlines

Simulating the spectra of Quasars: A simple disk-wind model for BALQSOs

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