The Nature of the OVI Absorbers at low z : their Connection with the Galaxies

The Nature of the OVI Absorbers at low z : their Connection with the Galaxies Bastien ARACIL University of Massachusetts, USA • Todd M. Tripp • Jason X. Prochaska • David V. Bowen • Brenda L. Frye

Why OVI Absorbers OVI tracer of hot gas ( T~105 - 106 K ) Hot gas in : IGM : the WHIM Predictions: Shock heated by gravitational infall into LSS (T~105 - 107 K), 30% to 40% of the baryonic mass (Fukugita et al. 1998; Stocke et al. 2005; Cen & Ostriker 1999; Davé et al. 1999,2001) FUSE & HST Observations: WHIM with OVI, 5% - 10% of the baryonic mass (Tripp et al. 2000; Savage et al. 2002; Danforth & Shull 2005) • Halos of Galaxies : the HVCs • Detected in OVI with FUSE around the Milky Way and Local Group. • OVI is an indicator of interface between between hot halos and cooler infalling gas • (Murphy et al. 2000; Sembach et al. 2000,2003, Collins et al. 2004) • Potential well of galaxy groups • OVI tracer of the intragroup gas in spiral-dominated group (Mulchaey et al. 1996) • Again, OVI indicator of the interface between infalling cool gas and hot intragroup medium. (Shull et al. 2004)

2 arcmin 8 OVI absorptions detected : z=0.04125 z=0.05895 0.05928 z=0.06244 z=0.13847 z=0.16548 z=0.17340 0.17360 PG1116+215 zem=0.1765 QSO

2 arcmin 8 OVI absorptions detected : z=0.04125 z=0.05895 0.05928 z=0.06244 z=0.13847 z=0.16548 z=0.17340 0.17360 PG1116+215 zem=0.1765

8 OVI absorptions detected : z=0.04125 z=0.06244 z=0.05895 0.05928 z=0.13847 z=0.16548 z=0.17340 0.17360 PG1116+215 zem=0.1765 820 330 90 130 Association: 130 310 • Closest galaxies at less than 500 km/s • Near Neighbor Method ~ Closest galaxies in velocity at less than 1Mpc 660 980 320 830

Associates OVI Absorbers – Galaxies Associations PG1116+215 : 8 OVI H1821+643 : 6 OVI PG0953+415 : 3 OVI No clear direct association  Include type or/and magnitude min(ρ) with |Δv| <500 km/s But correlation from MC simulation Near Neighbor method

Lyα absorptions Absorption Associated with a Spiral rich group LOS to the quasar HS0624+6907 (zem≈0.37) Lyα absorptions at zabs~0.0635, Δv ~ 1000 km/s

Absorption Associated with a Spiral rich group Absorber environment: - Several Abell Clusters - Clusters with similar redshift (0.07, 0.1) - A577 : no redshift, possibly @ z~0.064

Absorption Associated with a Spiral rich group Spectroscopic follow-up of the brightest galaxies : z [0.062;0.066] 10 galaxies within  < 2 Mpc Closest at  =140 kpc z [0.073;0.077] 7 galaxies z [0.100;0.114] 6 galaxies KPNO image (36’x36’)

Absorption Associated with a Spiral rich group Spectroscopic follow of the brightest galaxies : z  [0.062;0.066] 10 galaxies within  < 2 Mpc Closest at  =140 kpc z [0.073;0.077] 7 galaxies z [0.100;0.114] 6 galaxies KPNO image (36’x36’)

Absorption Associated with a Spiral rich group Filament at z~0.064 almost align with the line of sight

Absorption Associated with a Spiral rich group Metals - CIV, SiIII, SiIV detected - no OVI Modelisation • - Voigt profile fitting  N,b,z • CI model: (Sutherland & Dopita ,1993) • Narrow HI lines • Need T>104.9 K • But CIV widths give T~104 K

Absorption Associated with a Spiral rich group Metals - CIV, SiIII, SiIV detected - no OVI Modelisation • - Voigt profile fitting  N,b,z • CI model: (Sutherland & Dopita ,1993) • Narrow HI lines • Need T>104.9 K • But CIV widths give T~104 K • PI model: Cloudy • Z~Z , nH~10-3.9, log U=-2.5

Conclusions • Correlation between galaxies and OVI absorbers at low redshift + • Detection of a Filament at z~0.064 without OVI, photoionised and with T lower than 105 ?

2 arcmin 8 OVI absorptions detected : z=0.04125 z=0.05895 0.05928 z=0.06244 z=0.13847 z=0.16548 z=0.17340 0.17360 PG1116+215 zem=0.1765 • Select galaxies at less than 500 km/s

0.5 deg 2 arcmin 8 OVI absorptions detected : Z=0.04125 Z=0.05895 0.05928 Z=0.06244 Z=0.13847 Z=0.16548 Z=0.17340 0.17360 QSO PG1116+215 zem=0.1765

The Nature of the OVI Absorbers at low z : their Connection with the Galaxies