Recent Highlights from the High Resolution

Transmission Grating X-ray Spectrometer on the

Chandra X-ray Observatory Michael A. Nowak (MIT-CXC)

on behalf ofClaude Canizares and the Chandra-HETG

Group*(* Anything intelligent that I say, full credit to the group; idiotic statements wholly my

own!)

The Chandra X-ray Observatory:

Chandra History and Specs:

Third of NASA’s “Great Observatories”. Launched July 1999

High Altitude Orbit (132,000 km); 63.5 hour orbit

Up to 160 ksec viewing windows

Superb Spatial Resolution; 0.5”

ACIS-I (0.8-10 keV), ACIS-S (0.3-10 keV), HRC

Superb Spectral Resolution; E/ΔE = 2300-150 (0.1-6.4 keV)

HETG (HEG, MEG): 3 cm2@23 Å, 40 cm Å; LETG

Imaging Improvement:

Cas A Supernova Remnant

ROSAT

Spectral Improvement:

Protostar,TW Hydrae

Wavelength (Å)2 6 10 14 18 22 26

10

20

30

Cou

nts

/B

in

Wavelength (Å)

ASCA

Chandra HETG: The Most Sensitive 0.9-7 keV Instrument for Line Studies

Why We Want High Resolution:Spectroscopy Tells us the Composition of the

Universe

Abundances (see J. Drake’s talk); Phases, e.g., Warm, Hot, Cold, Solid (see J. Lee’s talk)

Spectroscopy is the Best Means to Study the Kinematics of Astrophysical Plasmas

Capella, SS 433, MCG--6-30-15, GRO J1655-40, SN1987A

Line Ratios can yield Temperatures, Densities, & Heating Mechanisms, e.g., Photo- or Collisional Ionization?

M81*, is it Advection Dominated?

Stellar Physics: Capella

42.2 lightyears from Earth, 6th Brightest “Star” in the Sky

Actually, 4 stars, with a Spectroscopic Binary - Capella Aa/Ab

Capella Aa 2.7 Msun, variable, beginning ascent to Red Giant Phase

Capella Ab 2.6 Msun, faster rotating, 104 day orbit

System is used to Study Stellar Physics and Chandra Calibration

Excellent Example of the Accuracy and Power of HETG!

Stellar Physics: Capella

MEG -1st OrderSpectra can be fit with

a 3 TemperaturePlasma Model

Stellar Physics: Capella

Capella Shows 10’s of km/sec velocity residuals

Real Effect! Barycenter & Space-craft Corrections need to be applied!

(Ishibashi et al. 2006)

Stellar Physics: Capella

Remaining Velocity Shifts Indicate X-ray Dominated by Capella Aa

Orbital Variability Also Seen in Line Fluxes

(Ishibashi et al. 2006)

Stellar Physics: Capella

Some lines indicate emission from both stars. Mg XII Doublet fitted velocity indicates 2:1 Aa:Ab ratio

Statistics and instrument resolution/stability allow us to carefully model other blends

(Ishibashi et al. 2006)

Higher Orders Allow Line Separation:

MEG 1stHEG 1stMEG 3rd

Ne X Lyα Doublet

Fe XVII

Fe XXIIINi XX

(Huenemoerder et al., in prep.)

More Extreme Kinematics - SS 433:

Two sided, relativistic jet with velocity 0.25 c

Orbital period of 13 days

Jet/disk precessing with 162 day period

Baryonic jet, as evidenced by emission

(Migliari et al., 2002)

QuickTime™ and aGIF decompressor

are needed to see this picture.

(Animation by L. Boroson, MIT)

Blue/Redshift Velocities Accurately Measured

(Lopez et al. 2006)

Recent Observation, Exiting Eclipse, fit with 5 Temperature APED Model

Stacking Lines to Perform Detailed Kinematic Modeling

Aug. 18

Aug. 16

Aug. 12

Velocity(km/s)

50,000

-30,000

Time (ks)

25 ks

Aug. 8

0

(Marshall et al., in prep.)

The Interstellar Medium:

Sd

Just as Quasars + Optical/UV Spectroscopy Probed the Structure of the Intergalactic Medium (IGM), X-ray Spectroscopy + X-ray Binaries Probes the Interstellar Medium (ISM)

Probes the Cold, Warm, and Hot Phases of the ISM

Driving Models of the ISM Distribution

Driving us to Improve Modeling of Edge/Resonance Line Structure

Testing/Calibrating Theoretical Models of Edge & Lines

Various Sight Lines Probed

4U 1636-53

Oxygen & Neon Edges Require 20 mÅ Shifts from Theoretical Values

Ne IX is Detection of the Hot Phase of ISM

O/Ne = 5.4 ± 1.6, Fe/Ne = 0.20 ± 0.03, Ne II/Ne I ≈ 0.3, Ne III/Ne I ≈ 0.07

The Interstellar Medium:

(Juett et al., 2004, 2006)

Model of Disk Distribution:

z (kpc)

log

(NH

sin(b

))

0.1 1.0 10 100

18

19

20

21

22

(Yao & Wang 2005, 2006)

The gas (∼108 Msun) is primarily concentrated around the Galactic disk within several kpc.nH = 5.0 x 10-3 cm-3 exp[-|z|/1.1kpc]

Total NH ∼1.6 x1019 cm-2

The Active Galactic Nuclei: MCG--6-30-15

Image: CXO

≈≈100 R100 RGG

Seyfert 1 Active Galactic Nucleus (AGN), offering an unobscured view of nucleus

Powered by efficient accretion through a “cold”, dense accretion disk

Powerful, compact central source of X-rays

Reflection Spectrum:

Broad Iron Line:

Heavily binned 522 ksec Chandra HEG (red)

XMM-Newton EPIC-pn (black)

(Young et al., in prep.)

MCG-6-30-15 : O I - O VIII (O0+ -

O7+), FeI - Fe XXVI (Fe0+ - Fe25+) !

Potential of tying our X-ray observations to a large body of work in UV, IR ...

Ability to probe sources with high extinction in the X-rays

Kinematic associations between UV and X-ray absorbers

More options for probing the ISM? Both in AGN & our own Galaxy

Inner Shell Resonance Lines: Probing Low Ionization (UV, IR) Processes in the X-rays(J. Lee et al., in prep.)

MCG−6-30-15

Galactic

O VO VIO VII He αO IV

O III

O II or FenOm

Atomic O I 1s-2p

O VI

The KLL (1s2s2p) Resonance of Li-like O VI (1s2 2s)

1s2

2s

Continuum

Augerprocess

130 eV

~ 560 eV2s

1s

2p

● Atomic Calculation : Pradhan 2000● Discovered in MCG-6-30-15 : J. Lee et al. 2001

O VI in MCG--6-30-15 : NOVI

~ 3 x

1017

cm-2

; EW ~ 32 mÅ

Inner Shell Resonance Lines: Probing Low Ionization (UV, IR) Processes in the X-rays

O VO VIO VII He αO IV

O VI

540 ksec MEG Spectra: Ne IX at High τ

(J. Lee et al., in prep.)

Winds Seen in X-ray Binaries:

(Miller et al., 2006)

GRO J1655-40: Binary in Outburst

(Miller et al., 2006)

Typical Blueshifts of 500 km s-1. Modeled as a constant ρ slab, with T=0.2-1 x 106 K, log ξ = 4.2-4.7

Argued that low velocity, high ionization mean magnetic driving

Note that a fair number of lines remain unidentified

M81*: Low Luminosity AGN

M81*ULX

Imaging Allows us to Separate Faint Source from Its Surroundings; Spectra

Allows us to Study the Accretion Flow onto the Nucleus

Closest extra-Galactic AGN with observable nucleus: 3.6 Mpc

Bolometric luminosity: L ≈ 1041 erg s-1

HST STIS spectroscopy MBH = 7.0 x 107 Msun

Low-luminosity AGN: L ≈ 10-5 LEdd

Has jet, similar to Sgr A*, but brighter

M81*: Low Luminosity AGN

Portion of the MEG Spectra:

Si XIVSi Kα

Mg XII Ne X Si XIII

(Young et al., in prep.)

Si XIII G = (f+i)/r = 0.8

Hybrid collisionally- and photo-ionized plasma [?]

Advection Dominated Accretion Flow?

ADAF outer radius, disk inner radius

Difficult to get strong Fe Kα

Even harder to get strong Si KαExpect Line Emission from

Transition Regions &Hot Plasma

Weak Fluorescenc

eFeatures

Close-up of the Fe Region:

Fe Kβ?

Fe XXV

Fe XXVI

Fe Kα

Fe XXVI redshifted by 3000 km s-1

Fe Kα, Fe XXVI consistent with 2000 km s-1 widths

Si Kα consistent with 600 ± 300 km s-1 widths

(Young et al., in prep.)

Supernova 1987A

Existing LETG Spectra

(Zhekov et al. 2005)

SN1987A: Getting Brighter & Bigger!

SNR 1987A - Expected HETG/MEG Observation

O VIII

Ne XMg XISi XIII

Co

un

ts/b

in~

0.5

" p

ixe

ls

Fe XVIINe XI

MEG minus-first order simulation; similar no. of counts in plus order.

O VII

MEG -1st Order Simulation Shown

270 ksec Observation with HETG (Canizares, PI), and 300 ksec with LETG (McCray, PI)

Spatial Information Available, both Via Image and Via Line Widths

Summary:The Imaging Improvement by Chandra is Incredibly

Impressive!

Spectral Resolution Improvement is Equally Impressive!

HETG is the Best Instrument for Studying Narrow Absorption & Emission Features in the 0.9-7 keV range

HETG is Used to Study a Wide Array of Astrophysics

Stars, X-ray Binaries, AGN, ISM, Supernovae ...

Data Leading us More Sophisticated Models, with Better Atomic Physics

Data can Help to Calibrate & Test Atomic Physics Models

We are Embarking Upon More Ambitious Observations that Combine Chandra’s Unique Spectroscopy and Imaging