x-ray grating spectroscopy mike crenshaw georgia state university x-ray grating spectroscopy of agn...

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

X-ray Grating

SpectroscopyMike Crenshaw

Georgia State University

X-ray Grating Spectroscopy of AGN



• Broad-band view

• X-ray spectral components:

– Soft X-ray excess

– X-ray NLR

– X-ray warm absorber

– Fe K (broad and narrow)

• The need for higher spectral resolution/sensitivity

X-ray Grating

Spectroscopy



X-ray Grating

Spectroscopy

Schematic Continuum SED for AGN

(hot dust)



IR Bump

Big Blue Bump

Hard X-rayhump

Soft X-rayexcess



X-ray Grating

Spectroscopy

Components of X-ray Emission

(Fabian, 2006, AN, 327, 943)

Reflection of coronalX-rays by cold disk

Compton upscattering ofdisk photons by hot corona

Thermal component(or something else?)



X-ray Grating

Spectroscopy

Soft X-ray Excess

• Seyfert 1s and quasars show a soft X-ray excess below 1 keV after subtraction of = 1.7 2.2 power-law.

• Previously explained by a thermal component (e.g., low-temperature Comptonization of accretion disk photons).



(Crummy, et al. 2006, MNRAS, 365, 1067)

XMM PN+MOS



X-ray Grating

Spectroscopy• But the excess has a fixed “temperature” (~0.2 keV), suggesting an atomic

rather than continuum origin (Done & Nayakshin, 2007, MNRAS, 377, L59):1) Relativistically broadened (“blurred”) emission lines from accretion-disk

reflection (Crummy, et al. 2006).2) High-velocity outflows of ionized gas absorbing the 0.7 - 3 keV range (Done &

Nayakshin, 2007; Chevallier, et al. 2006, A&A, 449, 493).

(Fabian, 2006, AN, 327, 943)

1) Reflection

(Gierlinski & Done, 2004, MNRAS, 349, L7)



2) Absorption



X-ray Grating

Spectroscopy

Narrow X-ray Emission Lines

3) Another soft-excess contributor: narrow X-ray emission lines Need high-resolution grating spectra to see their effect:



NGC 1068

(Kinkhabwala, et al. 2002, ApJ, 575, 732)



X-ray Grating

Spectroscopy

• Narrow radiative recombination continua (RRC) give temperatures of 10 eV photoionization dominates over collisional ionization (Guainazzi & Bianchi, 2007, MNRAS, 374, 1290).

• In nearby Seyferts with obscured (NGC 1068) or temporarily faint (NGC 4151) central engines, the majority of the soft X-ray emission comes from an extended region roughly coincident with the NLR:



(Ogle, et al. 2003, A&A, 849, 864)

CXO/HST Image of NGC 1068



X-ray Grating

Spectroscopy• In addition to photoionization, photo-excitation (resonance scattering)

plays an important role in producing the observed emission lines.• Turbulence can enhance this effect and boost resonance (r) lines, relative

to intercombination (i) and forbidden lines in He-like triplets (Armentrout, et al. 2007, ApJ, astro/ph 0705.0628 - see his poster):

Size:

< 940 pc

< 0.9 pc

< 0.05

Three-Component photoionization model for NGC 4151:

• “Low” is the extended X-ray NLR.• “Medium” and “High” similar to the warm-absorber components in NGC 4151 ( Kraemer et al. 2005, ApJ, 633, 693). A significant fraction of the X-ray emission lines comes from warm absorbers.



X-ray Grating

Spectroscopy

X-ray “Warm Absorbers”QuickTime™ and aTIFF (LZW) decompressor


(George, et al. 1998, ApJS, 114, 73)

• ASCA detected O VII and O VIII absorption edges in ~50% of Seyferts• Seyferts with X-ray absorbers also have blueshifted UV absorption

(Crenshaw et al. 1999, ApJ, 516, 750).• Blueshifted absorption lines seen by Chandra and XMM confirm mass

outflow (Kaspi et al. 2002, ApJ, 574, 643).



X-ray Grating

Spectroscopy

• Similar velocity coverage for X-ray absorbers and multiple UV components.

• Mass outflow rates are comparable to accretion rates (~ 0.01 M/yr ).

• Do X-ray absorbers separate into multiple narrow components, or are they more like winds?

(Gabel, et al. 2003, ApJ, 583, 178)



X-ray Grating

Spectroscopy

Absorption Variability in X-rays

• X-ray absorption primarily from broad UV component at vr = -500 km s-1.

• Deeper absorption in 2000 due to lower ionizing flux and larger NH.

• From variability, UV constraints: absorber is at ~0.1pc with vT 2100 km s-

1 (for a specific kinematic model, see Crenshaw &Kraemer, 2007, ApJ, 659, 250).

(Kraemer et al. 2005, ApJ, 633, 693)



NGC 4151



X-ray Grating

Spectroscopy

Hot Absorbers?• Several studies find evidence for very highly-ionized absorbers, with

U = 10 - 100 (Risaliti et al. 2005, ApJ, 630, L129).

• These hot absorbers tend to have large columns (NH 1023 cm-2), and could dominate the mass outflow rates, depending on their locations.

NGC 1365:Fe XXV and FeXXVI K and K absorption at -5000 and -1000 km s-1

(Risaliti et al. 2005)QuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.



X-ray Grating

Spectroscopy

Relativistic Outflows?

• Two broad absorption-line (BAL) quasars show outflows of highly-ionized gas with vr up to ~0.4c (Chartas, et al. 2007, AJ, 133, 1349).

• Narrow-line outflows up to ~0.2c have been claimed for a few non-BAL quasars (e.g., Pounds et al. 2006, 372, 1275), although this is more controversial (see McKernan et al. 2004, ApJ, 617, 232; Kaspi & Behar, 2006, ApJ, 636, 674).

Most of the high velocity/high ionization results are from non-grating observations.



Fe XXV or XXVI K absorption at ~0.2, ~0.4c.

(Chartas, et al. 2002, AJ, 579, 169)

APM 08279+5255QuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.

(Pounds, et al. 2006, MNRAS, 372, 1275)

L and He absorption at 0.13 - 0.15c

PG1211+143



X-ray Grating

Spectroscopy

Fe K Emission

(Fabian, 2006, The X-ray Universe 2005, p. 463)

• “Narrow” component seen in many AGN - “reflection” from BLR, NLR, or torus

• Broad component: fit with relativistic accretion disk model, velocity up to ~0.4c

• Rest-frame line center at 6.4 keV - consistent with emission from “cold” disk.



X-ray Grating

Spectroscopy

Broad Fe K - Accretion Disk Models

--- Schwarzschild BH, inner radius = 6 rg

--- Kerr BH, inner radius = 1.24 rg

(Fabian, 2006, AN, 327, 943)

Ultimate goal: fit profile to get the black hole spin (a) and accretion disk inclination Ultimate goal: fit profile to get the black hole spin (a) and accretion disk inclination



X-ray Grating

Spectroscopy

Complications

• Strong narrow Fe K contaminates the broad component.

– Grating observations are important for deconvolution.• Broad Fe K is often weak or absent (Reeves, 2003, ASP, 290, 35).

– A systematic XMM study indicates broad Fe K likely present in 75% of the Seyfert 1s studied (Nandra et al. 2006, 327, 1039).

• However, highly ionized absorption can mimic broad Fe K:– Fe L-shell absorption on the left, Fe K edge/absorption lines on the right

(Reeves et al. 2004, ApJ, 602, 648; Turner et al. 2005, ApJ, 618, 155).

– Once again, grating observations at high S/N would be helpful.

• Limited coverage at high energies makes it difficult to define the reflection component and therefore the “continuum”

– Suzaku observations are helpful.



X-ray Grating

Spectroscopy

Suzaku Observations

• Broad Fe KBroad Fe K claimed in 6 of 7 Compton-thin Seyfert galaxies (Reeves et al. 2006, AN, 327, 1097)

MCG-6-30-15MCG-6-30-15

XIS HXD



X-ray Grating

Spectroscopy

Transient, Narrow, and Moving



• NGC 3516 shows transient, narrow Fe K emission (Turner et al. 2002).

• Fe K periodically moves in energy between 5.7 and 6.5 keV over ~25 ks.

– Co-rotating flare model: r = 6 17 rg, M = 1 5 x 107 M (Iwasawa et al. 2004)

• Mrk 766 also shows moving narrow lines with a period of ~165 ks (Turner et al. 2006, A&A,445, 59).

– Fe K and continuum flux are correlated, indicating reflection from accretion disk at several AU from the SMBH (Miller et al. 2006, A&A, 453, L13).



(Turner et al. 2002, ApJ, 574, L123) (Iwasawa et al. 2004, MNRAS, 355, 1073)

NGC 3516



X-ray Grating

Spectroscopy

The End

OR, REALLY, JUST THE BEGINNING

x-ray grating spectroscopy mike crenshaw georgia state university x-ray grating spectroscopy of agn...

Documents

xray absorbers

soft xray emission

extended xray nlr

absorption slide

blurred emission lines

observed emission lines

blueshifted absorption

forbidden lines