Science Impacts of High Resolution
X-Ray Spectroscopy
Chairs: David P. Huenemoerder & M. Nowak
Endorsers:
D. Dewey, N. S. Schulz, H. L. Marshall C. R. Canizares (MIT)
N. Brickhouse J. Lee, J. Nichols (CfA)
T. Ayres (CASA)
M. Corcoran, S. Drake (GSFC)
T. Yakoob (Johns Hopkins)
A. Pollock (ESA)
The High-Energy Transmission Gratings on Chandra and the Reflection Grating Spectrometers on XMM-Newton have brought high
spectral resolution with high signal-to-noise to X-ray studies in a wide variety of astrophysical fields. Such fields include coronae of
cool stars; winds of hot stars; white dwarf and neutron star atmospheres; winds from active galaxies; supernova remnants; and
plasma in interstellar, intracluster and intergalactic media. The goal of the session is to introduce the science being performed with
the unique capabilities of high-resolution X-ray spectroscopy satellites to a broad range of astrophysicists. We will describe
the scientific advances made possible by high resolution X-ray spectroscopy, and how these studies fit within the context of both
low-resolution, broad band X-ray studies (i.e., Chandra and XMM CCD spectroscopy, Suzaku, SWIFT, RXTE, and INTEGRAL) and highresolution spectroscopy at other wavelengths (e.g., IR with Spitzer, and UV with HST). Time will be available for discussion of how these
current missions are laying the groundwork for future scientific work with Constellation-X, which will be a high-resolution X-ray
spectroscopic mission. Ample time will be devoted to discussion of science issues. In addition, participants will receive a summary of
resources including at-meeting contacts for off-line demonstrations and in-depth discussions.
Cambridge, CfA, CUC Meeting Apr. 09 2008
Science Impacts of High Resolution
X-Ray Spectroscopy
Talks: X-Ray Spectroscopy of Photoionized Plasmas
T. Kallman (GSFC)
Shocked Plasmas at high Dispersion
M. Gagne (W. Chester)
Posters (as presented):
Comparison of Spectral Capabilities of Current X-ray Satellites (M. Nowak et al.)
A Catalog of Chandra Grating Spectra (D. Huenemoerder et al.)
The HotGAS AGN HETG Data Facility and Highlights Unique to X-ray Gratings (Yakoob et al.)
Probing AGN Unific. with High-Res. Spectroscopic and Imaging Obs. of NGC 2110 (Evans et al.)
Chandra Gratings Observations of the Focused Wind in Cygnus X-1/HDE 226868 (Wilms et al)
Modelling The X-Ray Spectra of the SS 433 Jets (Marshall et al.)
Chandra HETG Large Program on the Magnetic CV EX Hya (Luna et al.)
Chandra HETG Spectra Of SN 1987A At 20 Years (Dewey et al.)
Coronal Structures in the Active Binary System CC Eri (Osten et al.)
The HETG Orion Legacy Project (Schulz et al.)
Status of Coll. Ioniz. Equil. Calcs and a New Approach to EM Determinations (Bryans et al)
Speeding Up Calculations of The Non-equilibrium Ionization Model (Ji et al.)
Improved Wavelength Accuracy for Reprocessed Grating Data (Nichols et al.)
Cambridge, CfA, CUC Meeting Apr. 09 2008
X-ray Spectroscopy of Photoionized Plasmas
T. Kallman (NASA/GSFC)
“A Picture is worth a thousand words… “(Bonaparte?)
“..but a spectrum is worth a thousand pictures..” (Ferland)
What is high resolution spectroscopy?
“I shall not today
attempt further to
define the kinds of
material I understand
to be embraced . . .
[b]ut I know it when I
see it ..” Justice Potter
Stewart 1964
Con-x
RXTE
epic
RGS
HETG
=> R>500 allows discrimination of He-like triplets, measurements of widths < 600 km/s
Why study spectra at high resolution?
• Puts the ‘physics’ in astrophysics
• High resolution spectra <=> line and edge features due to atomic
transitions
• Spectroscopy allows study of sources on small spatial scales
• Chance to get detailed quantitative results on:
• Abundances
• temperature
• kinematics
• But what we really want to study are the Exotic effects:
• Relativity
• magnetic processes (Blandford-Znajek, Poynting flux)
• What’s really going on close to compact objects, (eg. M/R for neutron star,
a/m for black hole).
• We have to understand the atomic spectra first in order to get to these
topics
• AGN: warm absorbers
• Warm absorbers close to home
• High Mass X-ray binaries
• ISM/IGM
• CVs
• Apologies to the many topics not discussed
Chandra HETG
Spectrum:
NGC 3783
•900 ksec observation
•>100 absorption features
•blueshifted, v~600 km/s
•broadened, by~300 km/s
•fit to 2 photoionization
model components
(Kaspi et al 2002)
The reality of spectroscopy: it requires
long observations
•
•
•
•
•
Typical fluxes (eg. For an AGN) ~0.02
photons/cm2/s Fmcrab
Grating effective area 10-100 cm2
Need ~103 energy channels
~10 photons/channel
--> tobs~ 5 105 s Fmcrab-1 A10-1
CONCLUDING REMARKS
• Spectroscopy is where the physics is.
• Grating spectroscopy has boosted X-Ray Astronomy to level with other branches
of astronomy and contributed to all fields of astrophysics
• AGN outflows: clues to the global mass budget
• Measuring column densities in emission =>
unifying Seyfert 1 absorber with Seyfert 2 emitter
• Abundance studies: detecting trace iron-peak elements from compact binaries
• Kinematics: Discerning binary and non-thermal motion in binary systems,
detecting outflows
• Detecting cold material and reflection geometry near compact objects
• Searching for our galactic halo and intergalactic gas
• This is challenging, and time consuming, but the insights are unique
• We need to continue to obtain grating observations, and to improve models to aid
in their interpretation.
Shocked Plasmas at
High Dispersion
Marc Gagné
West Chester University
David Cohen
Swarthmore College
Stan Owocki, Rich Townsend, Asif ud Doula
University of Delaware
Leisa Townsley, Pat Broos, Eric Feigelson
Penn State University
Stellar X-ray shocks: summary
1.
2.
3.
4.
X-ray line diagnostics:
1. ℛ=f/i: He-like forbidden-to-intercombination line ratios
2. Line broadening, shifts, asymmetries
Accretion shocks on T Tauri stars: TW Hya (K8 Ve)
Wind shocks around massive stars:
1. Line driving, shocks: early-O supergiants: ζ Pup (O4 If)
2. Magnetically channeled wind shocks: θ1 Ori C (O5.5 V)
3. Colliding-wind binaries: WR 140 (WC7 + O4)
4. New: τ Sco (B0 V), β Cru (B0.5 IV), θ2 Ori A (O9.5 V),
CEN 1A and 1B (O4 visual binary in M17)
Continuum diagnostics, non-equilibrium effects
H-like/He-like ratio is temperature sensitive
He-like ratio ℛ=f/i is a density/dilution diagnostic
Si XIV
Si XIII
Mg XII
1 Ori C
Mg XI
Ne X
ζ Pup
Ne IX
Stellar X-ray shocks: Conclusions
1.
2.
3.
4.
5.
X-ray shocks in most O-type supergiants
appear to form in clumpy winds.
Magnetically channeled wind shocks tend to
occur in mid-O to early-B stars in very young
clusters.
Colliding wind shocks require very high massloss rates; the CEN 1 stars in M17 may be the
youngest known CWS binaries.
TW Hya and other T Tauri stars appear to have
accretion-driven X-ray shocks.
So far, we see no clear evidence of temperature
non-equilibration or non-ionization
equilibrium in the post-shock, X-ray emitting
plasmas of hot stars.