the extended hi environment of m31 robert braun (astron)
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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 ~10-4-10-5 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
DLALy-forest
(Ly-limit)
Modeling the Cosmic Web ~30% baryons in galaxies~30% baryons in galaxies ( @ z = 0 )
•association with QSO absorbers with NHI =
1018 – 1022 cm-2
~30% baryons in warm-hot inter-galactic ~30% baryons in warm-hot inter-galactic
medium (WHIM)medium (WHIM)
•condensed, shock-heated phase: T ~ 105 –
107 K
•association with QSO absorbers with NHI =
1014 – 1018 cm-2
•ties in with evidence from FUSE OVI
absorption (Sembach et al. 2003) for Galactic
corona, R > 70 kpc, n ~10-4-10-5 cm-3
~30% baryons in diffuse inter-galactic medium~30% baryons in diffuse inter-galactic medium
•diffuse, photo-ionized phase: T ~ 104 K
•association with QSO absorbers with NHI =
1012 – 1014 cm-2
decreasing (micro- not macro-) neutral fraction decreasing (micro- not macro-) neutral fraction
with Nwith NHIHI
•~1% at NHI = 1017 cm-2, < 0.1% at NHI = 1013
cm-2
Hierarchical Galaxy Formation and the
“Missing Low Mass Companions”
high resolution numerical simulations predict an an
order of magnitudeorder of magnitude moremore low mass satellites than
observed with vc < 30 km/s: n(M) ~ M-2
Klypin et al. 1999, ApJ 522, 82Moore 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
Kep
ner
et
al.
19
99
, A
J 1
17
, 2
06
3
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 (<MHI> ~103 MSun)
high pressure (30 cm-3 K) => higher neutral fraction (<MHI> ~105 MSun)
expected numbers depend on host mass and search volume:
N(>Vmax,<d) = 1.06x103 (Mvir/1012 MSun) (Vmax/8 km/s)-2.75 (d/1 Mpc)
predicted population has steep power law in Vmax and therefore MHI!!
low Mvir 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 SurveyBraun, Thilker & Walterbos 2003, A&A, 406, 829 and 2004, 417, 421
• Auto-corr. drift-scan survey of 1800 deg2 centered on
M31
• ~380 hours observing Aug. 2002 – Oct. 2002
• 48 arcmin x 17 km/s res. over 60 x 30 deg., -1000 < V
< 6500 km/s
• 17 mJy/Beam (at V = 17 km/s), cf. HIPASS =14
mJy/Beam
• NNHIHI = 4 x 10 = 4 x 101616 cm cm-2-2 for emission filling the beam (10
kpc at 700 kpc)
(cf. HIPASS NHI ~ 4 x 1017 cm-2 in 15 arcmin
beam)
Galactic CHVCs Magellanic Stream and Wright’s HVC complex circum-galactic HI clouds and streamscircum-galactic HI clouds and streams of M31
and M33 M31/M33 filament near systemic velocityM31/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 faint, compact pop. centered on M31 systemic velocityvelocity•M31/M33 filament near systemic velocityM31/M33 filament near systemic velocity, NHI ~ 4x1017cm-2 (peak)
WSRT Wide-field HI Survey
Inte
gra
ted
neg
ati
ve v
elo
cit
y H
I, log
(NH
I) =
1
7,
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 faint, compact pop. centered on M31 systemic velocityvelocity•M31/M33 filament near systemic velocityM31/M33 filament near systemic velocity, NHI ~ 4x1017cm-2 (peak)
WSRT Wide-field HI Survey
Velo
cit
y o
f p
eak H
I in
LG
SR
fra
me
Braun & Thilker 2004, A&A, 417, 421
Dirty Channel Map
WSRT Wide-field HI Survey
Dir
ty B
eam
The M31 – M33 filament
•connects VSYS of
M31 and M33 (170
kpc projected)
•continues in anti-
M33 direction
•filamentary
structure within 30
kpc (GBT data)
•connects to
ongoing fueling of ongoing fueling of
both M31 and M33both M31 and M33
(from GBT imaging)
Braun & Thilker 2004, A&A, 417, 421
Cleaned Channel Map
WSRT Wide-field HI Survey
Dir
ty B
eam
The M31 – M33 filament
•connects VSYS of
M31 and M33 (170
kpc projected)
•continues in anti-
M33 direction
•filamentary
structure within 30
kpc (GBT data)
•connects to
ongoing fueling of ongoing fueling of
both M31 and M33both M31 and M33
(from GBT imaging)
Green Bank Telescope wide-field HI imaging of
M31Thilker, 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. 2002
• 2 kpc x 1 km/s res. over 95 x 95 kpc
• 6.6 mJy/Beam (at V = 18 km/s)
• NHI = 1.5 x 1017 cm-2 at 3 kpc resolution
extended rotation curve/warping outer HI edge, UV rad. field HI clouds and streamsHI 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
GBT wide-field HI imaging of M31Thilker et al. 2004, ApJL, 601, L39
Detection of three distinct HVC populations
1.1. tidal streamstidal 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)
2.2. diffuse filamentsdiffuse filaments and halo centered on M31
systemic velocity, possible interface to the cosmic
web
3.3. concentration of faint, compact HVCsconcentration 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 M31Braun, Corbelli, Thilker & Walterbos 2002 & 2004, in prep
• 163 pointings on 15 arcmin Nyquist-
sampled grid
• ~350 hours observing Aug. 2001 – Jan.
2002
• 50 pc x 2 km/s res. over the 80 kpc disk
• 1.4 mJy/Beam (at V = 2 km/s)
• NHI = 1.0, 3.5, 11 and 24 x 1018cm-2
@ 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 streamscircum-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
Bra
un
et
al.
20
03
, in
pre
p
From WSRT Mosaic
•current spatial coverage includes ~10 examples of near-in CHVCs (< 40 kpc)•multi-phase CNM/WNM structure •peak NHI ~ 1019 -1020 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, MHI ~ 106 MSun , 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 extensive tidal stream, halo and discrete HVC populationspopulations •combined low NHI 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): = 150-200 kpc
Th
ilker
et
al.
20
04
, A
pJL
, 6
01
, L3
9
Bra
un
& T
hilker
20
04
, A
&A
, 4
17
, 4
21
wide-field GBT data wide-field WSRT data
M33
Braun & Thilker 2003, in prep.
The M31 discrete HVC Population (within 40 kpc radius)
•mass distribution:
MHI = 105 – 107
MSun
• linewidth-mass
roughly consistent
with:
MDM ~ 100 MHI
• expect N ~ 20
within 40 kpc radius
of M31 and detect
22
Here are the Here are the
missing low mass missing low mass
companions !!companions !!
wide-field GBT data
“Missing Low Mass Companions”
The M31 – M33 filament
•connects VSYS of
M31 and M33 (170 kpc projected)
•continues in anti-M33 direction
•connects to ongoing fueling of ongoing fueling of both M31 and M33both M31 and M33 (from GBT imaging)
•relative distance and radial velocity imply M33 is likely approachingapproaching M31: makes tidal origin unlikely
Bra
un
& T
hilker
20
04
, A
&A
, 4
17
, 4
21
wide-field WSRT data
Imaging the low-z Cosmic Web
the first detection of the “cosmic web”/ WHIM in the first detection of the “cosmic web”/ WHIM in HI emissionHI emission
The M31 – M33 filament•extremely diffuse in bridge region
(same low NHI in GBT and WSRT TP beams)
Bra
un
& T
hilker
20
04
, A
&A
, 4
17
, 4
21
wide-field WSRT data GBT confirmation (30 min ON/OFF)
Imaging the low-z Cosmic Web
Cosmic Web and QSO absorption linesBraun & Thilker 2004, A&A, 417, 421
•composite NHI 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 datagood agreement with QSO absorption line data
the first image of a Lyman Limit absorption Systemthe first image of a Lyman Limit absorption System
WSRT mosaic: disk + cores
wide-field GBT: streams + CHVCs
wide-field WSRT: M31-M33 filamentQSO 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 (MDM ~ 100
MHI)
total HI mass is modest, about 2% of M31 HI
mass: ~108 MSun
total HII mass is more substantial; ~ 109 MSun 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 ~150-
200 kpc)
composite NHI 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!