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Front. X-ray Studies of Galaxies and Galaxy Systems Jesper Rasmussen Ph.D. Defence Astronomical Observatory, Univ. of Copenhagen 17th March 2004. Outline. Background: X-rays from galaxy systems XMM-Newton observations of two galaxy groups X-ray haloes of simulated disk galaxies

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  1. Front X-ray Studies of Galaxies and Galaxy Systems Jesper Rasmussen Ph.D. Defence Astronomical Observatory, Univ. of Copenhagen 17th March 2004

  2. Outline • Background: X-rays from galaxy systems • XMM-Newton observations of two galaxy groups • X-ray haloes of simulated disk galaxies • Chandra observations of a dwarf starburst galaxy • Summary

  3. Collaborators, papers Main collaborators: Kristian Pedersen, Sune Toft (AO, Copenhagen) Jesper Sommer-Larsen, Martin Götz (TAC, Copenhagen) Trevor Ponman (Univ. of Birmingham, UK) Papers (1) Groups: Rasmussen & Ponman (2004), MNRAS, in press (2+3) Disk galaxies: Rasmussen, Sommer-Larsen, Toft, Pedersen (2004), MNRAS, 349, 255 + Toft et al., 2002, MNRAS, 335, 799 (4) XMM simulations: Rasmussen, Pedersen, Götz (2004), astro-ph/0202022 (5) Dwarf starburst: Rasmussen, Stevens, Ponman (2004), in preparation

  4. X-rays from galaxy systems X-ray emission: Thermal emission from hot (~107 K) gas.  Formation of structure: Gas infall in dark matter halo, compression and (shock) heating of gas. Evolution of structure: Processes affecting hot gas properties (galaxy winds, nuclear outflows, cooling, …) Galaxies: Violent processes in the interstellar medium, interactions with environment… Cosmology: Detection of distant systems; gas (baryon) content  constraints on Ωm

  5. Outline • XMM-Newton observations of two galaxy groups • X-ray haloes of simulated disk galaxies • Chandra observations of a dwarf starburst galaxy

  6. X-rays from two galaxy groups • Goal: Study large-radius properties of groups for the first time. 1 • Two groups, atz = 0.18andz = 0.256, selected from ROSAT pointed observations. 2 • XMM-Newton 22 ks exposure (single pointing)  15 arcmin  Smoothed 0.4-2.5 keV image (all 3 XMM/EPIC cameras).

  7. Groups: X-ray + optical Dig. Sky Survey 1 2 WARPS, R-band WARPS, I-band

  8. Groups: Results Surface brightness fit using -model: 1 2 β= 0.49 rc = 75 kpc (h=0.75) Extent = 570 kpc β= 0.62 rc=170 kpc Extent = 650 kpc Fitting of thermal plasma models to spectra: T-1 kT = 1.7 +/- 0.1 keV Z = 0.3 +/-0.1 Zsun kT = 2.4 +/- 0.4 keV Z = 0.3 +/- 0.2 Zsun

  9. { 1. M = (5.1+/- 0.5) x 1013 Msun, rdet/r200 = 0.74 2. M = (1.0+/- 0.2) x 1014 MSun, rdet/r200 = 0.66  Groups: Implications Gas mass fraction Entropy, S = T/Ne2/3 2 ~0.14 & ~0.17 (h=0.75) 1

  10. Groups: Summary • X-rays detected to ~ 0.7 r200 in two X-ray bright groups. • Gas mass fraction rises with radius, global value similar to clusters •  • Groups could contain many more baryons than is often supposed (could help solve the ”missing baryon” problem) • Entropy distribution: • (1) confirms: groups are not ”downscaled clusters” • (2) rules out simple formation scenarios that assume pre-heating and smooth accretion of gas.

  11. Outline • XMM-Newton observations of two galaxy groups • X-ray haloes of simulated disk galaxies • Chandra observations of a dwarf starburst galaxy

  12. Disk galaxy halos (1) z = 0 (Toft et al. 2002) agreement with observations. (2) Here predict evolution with redshiftfor MW-like galaxies. Idea: Use cosmological simulations to compute X-ray properties of hot halos of disk galaxies. Cosmological simulations: Sommer-Larsen et al (2003). Include star formation, feedback, radiative cooling, UV radiation.

  13. LX <1/T> Simulations Disk galaxy halos: Lxvs z Accretion rate of cold (T< 3 x 104 K) gas onto disk :

  14. Chandra Deep Field North: 1 Ms(covers Hubble Deep Field-N) Disk galaxy halos: High-z constraints Hornschemeier et al. 2002: ________ CDF-N spectroscopic sample - - - - - CDF-N photometric sample

  15. > 10 halos per deg2(to z = 0.3 in 1 Ms) Halos: Detection prospects XEUS 10% of MW-like galaxies to z=0.3 Surface brightness vs vertical disk distance |z|

  16. Halos: Summary • Halo Lx increases 5-10 times from z = 0 to z = 1. Reflects the evolution of accretion rate of cold gas onto the galactic disk. • Evolution in agreement with deep X-ray data. • Detection of halos of Milky Way-like galaxies at cosmological distances must await the next generation of X-ray instrumentation.

  17. Outline • XMM-Newton observations of two galaxy groups • X-ray haloes of simulated disk galaxies • Chandra observations of a dwarf starburst galaxy

  18. NGC1800: An embedded starburst • Goal: Study interactions between galactic wind and ambient gas – is wind confined? • NGC1800: Dwarf starburst galaxy, D ~ 7 Mpc. • Galaxy group: 6 members, σ = 260 km/s. • Chandra/ACIS 45 ks exposure D25(25 mag/arcsec2) NGC1800, B-band, 6 x 6 arcmin

  19. NGC1800 observations - or ”how X-ray data can also appear” 0.3-2 keV raw image

  20. NGC1800 – diffuse X-rays X-ray/optical overlay 0.3-5 keV, adaptively smoothed D25 Dspec ~ 2kpc Results from thermal model fit: kT = 0.25 +0.05/-0.03 keV (1σ) Z = 0.05 +0.22/-0.04 Zsun (1σ) Extent ≈ 2 kpc Lx = 1.3 +/- 0.3 x 1038 erg/s

  21. NGC1800 group LX - σ relation (ROSAT)+ σ - T relation  Expectation:kT ~ 0.7 keV LX ~ 1.5 x 1042 erg/s ~ 1500 counts/CCD But ”no” detection (~100 counts/CCD)  LX < 1041 erg/s

  22. VLA HI map (Hunter et al. 1994) NH: 0.511 x 1020 cm-2 1'≈ 2 kpc Blow-out criterion: > 1 (Mac Low & McCray 1988 – blast wave dynamics in stratified atmosphere) NGC1800: Wind blow-out?

  23. Conical geometry: Sr-1.3 α  1.2. But M82 & NGC253: α  0.9 & 1.3 …so no clear evidence of wind confinement. NGC1800: Wind  IGM Galactic starburst wind confined by the IntraGroup Medium (IGM)? (PIGM< Pwind )  Freely expanding wind: ner-α, α = 2(Chevalier & Clegg 1985)

  24. X-rays from dwarf starbursts X-ray activity vs ”mass” X-ray activity vs star formation activity Gas temperature vs ”mass”

  25. NGC1800: Summary • NGC1800: Most distant dwarf starburst with detection of diffuse X-ray emission. • X-ray gas can probably leave the galaxy - but no clear evidence for wind-IGM interaction (and no detection of hot gas in the group). • X-ray emission from dwarf starbursts governed by starburst activity rather than mass of host galaxy.

  26. Groups • X-rays detected to ~ 0.7 r200. Gas mass fraction rises with radius, global value similar to clusters. Entropy distribution rules out certain formation scenarios. Disk galaxy halos • Halo Lx increases 5-10 times from z = 0 to z = 1. Evolution in agreement with deep X-ray data. Dwarf starburst • Most distant dwarf with diffuse X-rays. No clear evidence for wind-IGM interaction. X-rays from dwarf starbursts governed by starburst activity. XMM sim’s • Versatile tool for a variety of applications. Small clusters detectable to z > 1 in 10 ks. Summary: Results

  27. Circular velocity Vc: ”generalized” Schechter function:  > 10 halos per deg2(to z = 0.3 in 1 Ms) Halos: Detection prospects XEUS 10% of MW-like galaxies to z=0.3 + Surface brightness vs vertical disk distance |z|

  28. Summary: Comparison of sources Bolometric LX , Ωm = 1, ΩΛ = 0, h = 0.5

  29. Outline • XMM-Newton observations of two galaxy groups • X-ray haloes of simulated disk galaxies • Chandra observations of a dwarf starburst galaxy • Simulating XMM-Newton observations

  30. XMM simulations: Setup Motivation: Distant clusters in XMM ”blank-sky” pointings?(but many other possible applications) Source field setup: Clusters from Press-Schechter and N-body sim’s, point sources, backgrounds. Method: Input to SciSim (ray-tracing software), construct data sets from output.

  31. XMM simulations: Example (test) 20 ks exposure of T ~ 5 keV cluster at z = 0.6

  32. XMM simulations: Blank-sky Wavelet detections, > 6σ Input source field, 30 x 30 arcmin 0.5-2 keV output image (all EPIC)

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