1 / 20

Ron Remillard Kavli Center for Astrophysics and Space Research

INPE Advanced Course on Compact Objects Course IV: Accretion Processes in Neutron Stars & Black Holes. Ron Remillard Kavli Center for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/INPE_IV.3.ppt. IV.3 X-ray States of Accreting NSs.

finna
Download Presentation

Ron Remillard Kavli Center for Astrophysics and Space Research

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. INPE Advanced Course on Compact ObjectsCourse IV: Accretion Processes in Neutron Stars & Black Holes Ron Remillard Kavli Center for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/INPE_IV.3.ppt

  2. IV.3 X-ray States of Accreting NSs • Classifying Atolls, Z-sources, and X-ray Pulsars • Spectral Shapes and X-ray Colors • Color-color and color-intensity diagrams • X-ray spectra and power-density spectra • Soft and Hard States of Atoll Sources • X-ray Spectra and the Model Ambiguity Problem • The L vs. T4question for NSs • Hard State and Jets • Z Sources • Identifications and the two Groups • X-ray Power Density Spectra • X-ray Spectral Models • XTE J1701-462: the first Z-type transient

  3. Accreting NS Subclasses Cackett et al. (2006) • HMXB/pulsar (o) • Hard spectra: e.g., power-law photon index < 1.0 at 1-20 keV; •  easiest distinguished via gross spectral shape • weakly magnetized, accreting NS (D) • BH Binaries and • candidates (squares) • filled symbol: persistent • open symbol: transient

  4. Energy Spectra & Power Spectra of Accreting NS

  5. Accreting NS Subclasses • Atolls and Z-sources: X-ray spectra steeper than HMXB pulsars; • distinguished with color-color and color-intensity diagrams. • choose 4 energy bands {A, B, C, D} in order of increasing energy • soft color = B/A hard color = D/C • atoll transient bright atoll source Z source extreme island, island, banana branch horizontal, normal, and and banana branches (upper and lower) flaring (here curled) braches Top to bottom:

  6. Atoll-type Transients: Aql X-1, 4U1608-52 RXTE ASM: 10 outbursts per source

  7. Atoll-type Transients: combine all outbursts hard color: 8.6-18 / 5.0-8.6 keV ; soft color 3.6-5.0 / 2.0-3.6 keV  soft (banana), intermediate (island), hard (extreme island) states (Lin, Remillard, & Homan 2007)

  8. Atoll Spectra: Model Ambiguity (25 year debate) Eastern Model: A multi-color disk (MCD) + Comptonized blackbody (BB) Western model: BB + Comptonized MCD For each, Comptonization can be a simple slab model (Tseed, Tcorona), or an uncoupled, broken power law (BPL). All fits are good! Hard state: hot corona; moderate opt. depth; cool BB or MCD; Compt. dominates Lx Soft state: 3 keV corona; high opt. depth; thermal and Compt. share Lx

  9. Performance Test: L(BB or MCD) vs. T Eastern Model: MCD behavior unacceptable in soft state Western model: BB Lx is not T4, in soft state, but physics of boundary layer evolution is a complex topic. hard state: Lx growth is closer to T4 line (i.e., constant radius). LMCD (1038 erg/s at 10 kpc) -------------- LBB (1038 erg/s at 10 kpc)

  10. Solution to problem with atoll soft state? soft state: BB + MCD +weak BPL (constrainedG < 2.5 ; Ebreak = 20) hard state: Western (BB + BPL) top line: R = Rburst lower line: R = 0.2 Rburst LMCD (i=60o) and LBB (1038 erg/s at 10 kpc)  Rns< RISCO?

  11. Power Continuum vs. Comptonization 2 Atoll transients rms power in power density spectrum vs. fraction of energy (2-20 keV) for Comptonization Black Holes: Double-themal model: atolls and BH very similar In rms power vs. Comptonization fraction

  12. Double-thermal Model: View of the Hard State LBB may track the accretion rate at NS surface If dm/dt (disk) = dm/dt (BL), then the hard state has too much rad. efficiency (e.g. line at 0.01 LEDD). Alternatively, along lines of constant L(BPL+MCD), the hard state shows 6X less dm/dt reaching the NS surface, compared to the soft state.

  13. ASM Light Curves of Z Sources GX5-1 GX340+0 Cyg X-2 Sco X-1 GX349+2 GX17+2

  14. Long-term color-color diagrams of Zs GX5-1 GX340+0 Cyg X-2

  15. Long-term color-color diagrams of Zs Sco X-1 GX349+2 gx17+2

  16. Properties of Z-branches Flaring Branch Normal Branch Horizontal Branch

  17. Hard X-ray Components of Z Sources RXTE Obs. of Sco X-1 (D’Amico et al. 2001) Transient hard tail ; not fixed in color-color branches ; but spectral shape does vary with color-color position

  18. Spectral Fits for Z Sources BeppoSAX Obs. of GX17+2 (Di Salvo et al. 2000) Horizontal Branch: 8% power law (1-200 keV). ; Normal branch: no hard tail upper HB lower NB

  19. Spectral Fits for Z Sources BeppoSAX Obs. of GX349+2 (Di Salvo et al. 2001) Normal Branch vertex has hard tail ; Flaring branch is very soft

  20. First Transient Z-Source: XTEJ1701-462 Homan et al. 2006 + Atels by Homan et al. in 2006 and 2007 t1: Zs like GX5-1 t2: Zs like Sco X-1 t3: X-ray bursts t4: Atoll behavior --t1 --t2 --t3 --t4 + efforts to model the X-ray spectra, for physical insights about Z-branches: HB, NB, FB

More Related