The Extended HI Environment of M31 Robert Braun (ASTRON)

Outline Origins of Environmental HI tidal debris modeling the cosmic web modeling low-mass companions M31 HI Surveys from 50 pc to 200 kpc wide-field WSRT: 60x30 deg wide-field GBT: 7x7 deg WSRT mosaic: 6x3 deg The M31 HI Environment

Origins of Environmental HI Tidal Debris Mag. Stream is obvious Galactic example for HI growing number of (long-lived) stellar stream discoveries Condensations in Coronal Gas / Cosmic Web / WHIM evidence from FUSE OVI absorption (Sembach et al. 2003) for Galactic corona, R > 70 kpc, n ~ cm -3 kinematic association with HVCs Gaseous Counterparts of Low-Mass Dark-Matter Halos “missing” satellites (Blitz et al. 1999, Braun & Burton 1999)

Modeling the Cosmic Web high res. num. sim. predict cosmic web of filaments between galaxies apparent correspondence with QSO absorbers Dave et al. 1999, ApJ 511, 521, 2001, ApJ 552, 473

Modeling the Cosmic Web strong (density-dependent) evolution with cosmic epoch collapse of over-dense regions yields greater proportion of WHIM (z=0) Dave et al. 1999, ApJ 511, 521 WHIM DLA Ly-forest (Ly-limit)

Modeling the Cosmic Web ~30% baryons in galaxies ~30% baryons in galaxies z = 0 ) association with QSO absorbers with N HI = – cm -2 ~30% baryons in warm-hot inter-galactic medium (WHIM) condensed, shock-heated phase: T ~ 10 5 – 10 7 K association with QSO absorbers with N HI = – cm -2 ties in with evidence from FUSE OVI absorption (Sembach et al. 2003) for Galactic corona, R > 70 kpc, n ~ cm -3 ~30% baryons in diffuse inter-galactic medium diffuse, photo-ionized phase: T ~ 10 4 K association with QSO absorbers with N HI = – cm -2 decreasing (micro- not macro-) neutral fraction with N HI ~1% at N HI = cm -2, < 0.1% at N HI = cm -2

Hierarchical Galaxy Formation and the “Missing Low Mass Companions” an order of magnitude more high resolution numerical simulations predict an order of magnitude more low mass satellites than observed with v c < 30 km/s: n(M) ~ M -2 Klypin et al. 1999, ApJ 522, 82 Moore et al. 1999, ApJ 524, L19

Mini-halo Modeling calculations in isolated, inter-galactic environment as function of z early ionization and baryon evaporation recent recombination/condensation, HI phase is likely dominant little chance of internal star formation Kepner et al.1999, AJ 117, 2063 Kepner et al. 1997, ApJ 487, 61 “Missing Low Mass Companions” evolutionary and mass sequence

HI content strongly dependant on local IGM pressure: low pressure (1 cm -3 K) => low neutral fraction ( ~10 3 M Sun ) high pressure (30 cm -3 K) => higher neutral fraction ( ~10 5 M Sun ) expected numbers depend on host mass and search volume: N(>V max,<d) = 1.06x10 3 (M vir /10 12 M Sun ) (V max /8 km/s) (d/1 Mpc) predicted population has steep power law in V max and therefore M HI !! low M vir galaxies will NOT have detectable populations for two reasons: (1) IGM pressure and (2) small potential Sternberg, McKee & Wolfire 2002, ApJS 143, 419 “Missing Low Mass Companions” Mini-halo Modeling

WSRT Wide-field HI Survey Braun, Thilker & Walterbos 2003, A&A, 406, 829 and 2004, 417, 421 Auto-corr. drift-scan survey of 1800 deg 2 centered on M31 ~380 hours observing Aug – Oct arcmin x 17 km/s res. over 60 x 30 deg., < V < 6500 km/s  17 mJy/Beam (at  V = 17 km/s), cf. HIPASS  =14 mJy/Beam  N HI = 4 x cm -2  N HI = 4 x cm -2 for emission filling the beam (10 kpc at 700 kpc) (cf. HIPASS  N HI ~ 4 x cm -2 in 15 arcmin beam)  Galactic CHVCs  Magellanic Stream and Wright’s HVC complex circum-galactic HI clouds and streams  circum-galactic HI clouds and streams of M31 and M33  M31/M33 filament near systemic velocity

Dirty Channel Maps WSRT Wide-field HI Survey

Cleaned Channel maps WSRT Wide-field HI Survey

Braun & Thilker 2004, A&A, 417, 421 > 100 newly detected compact features Mag. Stream apo-galacticon tail, Wright’s Cloud faint, compact pop. centered on M31 systemic velocity faint, compact pop. centered on M31 systemic velocity M31/M33 filament near systemic velocity M31/M33 filament near systemic velocity, N HI ~ 4x10 17 cm -2 (peak) WSRT Wide-field HI Survey Integrated negative velocity HI, log(N HI ) = 17, 17.5, 18,...

Braun & Thilker 2004, A&A, 417, 421 > 100 newly detected compact features Mag. Stream apo-galacticon tail, Wright’s Cloud faint, compact pop. centered on M31 systemic velocity faint, compact pop. centered on M31 systemic velocity M31/M33 filament near systemic velocity M31/M33 filament near systemic velocity, N HI ~ 4x10 17 cm -2 (peak) WSRT Wide-field HI Survey Velocity of peak HI in LGSR frame

Braun & Thilker 2004, A&A, 417, 421 Dirty Channel Map WSRT Wide-field HI Survey Dirty Beam The M31 – M33 filament connects V SYS of M31 and M33 (170 kpc projected) continues in anti-M33 direction filamentary structure within 30 kpc (GBT data) ongoing fueling of both M31 and M33 connects to ongoing fueling of both M31 and M33 (from GBT imaging)

Braun & Thilker 2004, A&A, 417, 421 Cleaned Channel Map WSRT Wide-field HI Survey Dirty Beam The M31 – M33 filament connects V SYS of M31 and M33 (170 kpc projected) continues in anti-M33 direction filamentary structure within 30 kpc (GBT data) ongoing fueling of both M31 and M33 connects to ongoing fueling of both M31 and M33 (from GBT imaging)

Green Bank Telescope wide-field HI imaging of M31 Thilker, Braun, Lockman, Corbelli, Walterbos & Murphy 2004, ApJ 601, L39 6 OTF passes of 7 x 7 deg. on M31 (6 of 5 x 5 deg. on M33, & cross-cuts) ~70 hours observing July - Sept kpc x 1 km/s res. over 95 x 95 kpc  6.6 mJy/Beam (at  V = 18 km/s)  N HI = 1.5 x cm -2 at 3 kpc resolution  extended rotation curve/warping  outer HI edge, UV rad. field HI clouds and streams !!!  HI clouds and streams !!!

 V = 36 km/s GBT wide-field HI imaging of M31

 V = 72 km/s GBT wide-field HI imaging of M31

Thilker et al. 2004, ApJL, 601, L39 Detection of three distinct HVC populations 1.tidal streams 1.tidal streams: partial coincidence with the giant M31 stellar stream of Ibata et al. 2001, Ferguson et al. 2002, McConnachie et al. 2003, some apparent interactions with M31 disk (eg. NGC 205 stream) 2.diffuse filaments 2.diffuse filaments and halo centered on M31 systemic velocity, possible interface to the cosmic web 3.concentration of faint, compact HVCs 3.concentration of faint, compact HVCs centered on M31 systemic velocity which follow kinematic pattern of outer disk rotation confirmation (with very clean GBT beam) of faint WSRT auto- corr. detections

WSRT HI mosiac of M31 Braun, Corbelli, Thilker & Walterbos 2002 & 2004, in prep 163 pointings on 15 arcmin Nyquist-sampled grid ~350 hours observing Aug – Jan pc x 2 km/s res. over the 80 kpc disk  1.4 mJy/Beam (at  V = 2 km/s)  N HI = 1.0, 3.5, 11 and 24 x cm 120, 60, 30 and 20” (  V=20 km/s)  extended rotation curve / warping  outer HI edge / UV radiation field  CNM / WNM in disk circum-galactic HI clouds and streams  circum-galactic HI clouds and streams

WSRT HI mosiac of M31 50 pc x 2 km/s res. over the 80 kpc disk  most detailed ISM cube yet made Braun et al. 2003, in prep

From WSRT Mosaic current spatial coverage includes ~10 examples of near-in CHVCs (< 40 kpc) multi-phase CNM/WNM structure peak N HI ~ cm -2 complex internal kinematics Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

New Pointed Observations (Dec. 2003) deep pointed obs. of 10 sub- structures (9 around M31, plus 1 around M33) compact cores detected in all fields except M31/M33 filament fields Westmeier, Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

complex sub-structure adjacent to “giant stellar stream” several “intersecting” filaments with smoothly varying velocity bright isolated clumps, M HI ~ 10 6 M Sun, internal  V ~ 30 km/s kinematic analysis now underway Westmeier, Braun & Thilker 2004, in prep. High resolution imaging of M31 CHVC Cores

The M31 HVC Populations extensive tidal stream, halo and discrete HVC populations extensive tidal stream, halo and discrete HVC populations combined low N HI distribution has 25 kpc projected exp. scale- length  the discrete population of M31 is less extensive than predicted by the Galaxy model of De Heij, Braun and Burton (2002):  = kpc Thilker et al. 2004, ApJL, 601, L39 Braun & Thilker 2004, A&A, 417, 421 wide-field GBT datawide-field WSRT data M33

Braun & Thilker 2003, in prep. The M31 discrete HVC Population (within 40 kpc radius) mass distribution: M HI = 10 5 – 10 7 M Sun linewidth-mass roughly consistent with: M DM ~ 100 M HI expect N ~ 20 within 40 kpc radius of M31 and detect 22  Here are the missing low mass companions !! wide-field GBT data “Missing Low Mass Companions”

The M31 – M33 filament connects V SYS of M31 and M33 (170 kpc projected) continues in anti-M33 direction ongoing fueling of both M31 and M33 connects to ongoing fueling of both M31 and M33 (from GBT imaging) approaching relative distance and radial velocity imply M33 is likely approaching M31: makes tidal origin unlikely Braun & Thilker 2004, A&A, 417, 421 wide-field WSRT data Imaging the low-z Cosmic Web

the first detection of the “cosmic web”/ WHIM in HI emission  the first detection of the “cosmic web”/ WHIM in HI emission The M31 – M33 filament extremely diffuse in bridge region (same low N HI in GBT and WSRT TP beams) Braun & Thilker 2004, A&A, 417, 421 wide-field WSRT data GBT confirmation (30 min ON/OFF) Imaging the low-z Cosmic Web

Cosmic Web and QSO absorption lines Braun & Thilker 2004, A&A, 417, 421 composite N HI distribution from WSRT mosaic, GBT, wide-field WSRT normalization from HIPASS BGC ( Zwaan et al. 2003, AJ, 125, 2842 ) good agreement with QSO absorption line data  good agreement with QSO absorption line data  the first image of a Lyman Limit absorption System WSRT mosaic: disk + cores wide-field GBT: streams + CHVCs wide-field WSRT: M31-M33 filament QSO Abs. line data Imaging the low-z Cosmic Web

Conclusions M31 has rich HI environment of: tidal debris, halo components and a discrete cloud population linewidth-mass relationship for discrete pop. suggests very strong DM dominance (M DM ~ 100 M HI ) total HI mass is modest, about 2% of M31 HI mass: ~10 8 M Sun total HII mass is more substantial; ~ 10 9 M Sun if x = 0.9 and possibly much more in the halo component (x > 0.99 !) total detected extent, R ~ 150 kpc, but centrally concentrated with h  ~ 25 kpc (and not  ~ kpc) composite N HI consistent with QSO abs. line data at z=0; here are images of the absorbers! kinematic study of the cosmic web is now in reach!