History of the problem (incomplete and perhaps biased) ... b. core/cusp problem
.... et al.1987. Palunas &. Williams 2000 better use HI, since it goes farther out ...
Dark Matter in Galaxies A. Bosma Observatoire de Marseille (actually LAM / OAMP) History of the problem (incomplete and perhaps biased) Focus on recent problems in the field a. dark matter in spirals b. core/cusp problem c. dark matter in ellipticals d. galaxy formation & the future
Dark Matter on various scales solar neighbourhood galaxy scale (rotation curve studies, etc.) group scale (Local Group ''timing'', etc.) clusters of galaxies large scale structure Universe as a whole historically seemingly unconnected, but nowadays profound connections
Zwicky 1933 : dunkle Materie
Coma = 7038 ± 1020
If this should prove to be true ...
Colless & Dunn 1996
History by romantics ...
Coma = 7038 ± 1020
The 18” was installed in 1935; Zwicky published his DM calculation in 1933
Hubble & Humason 1931
6657 ± 1060 km/s for 23 galaxies, 23 years after 1933 Humason, Mayall & Sandage (1956)
Schwarzschild 1954
Neumann et al. 2003
baryon problem White et al. 1993
Coma = 7038 ± 1020
Concordance model : Ostriker & Steinhardt 1995
Dark Matter 'proof ' lensing + Xray gas
Clowe et al. (2006) ApJ 648, L109
Supernovae : dark energy era
Coma = 7038 ± 1020
Dark energy ????
Coma = 7038 ± 1020
Mass budget
Fukugita & Peebles 2004
Coma = 7038 ± 1020
Spergel et al. 2003, 2006
Steigman astroph/0511534 Fields/Sarkar astroph/0601514
Zwicky : interesting person
Who the hell are you !? '' ... We are eager therefore to pursue achievements, which can be closed as a masterpiece, which can be done alone and which nobody will question. The climb of a new mountain or a new difficult path in the mountains is such an achievement. ... ''
Zwicky (1971) ''red book'' David Hilbert's admonition ''be brief in all writings'' ''try to present your life's work in ten minutes''
Knowledge, Methods, Clarity
Logic of scientific discovery (Popper) and/or/versus sociology of research (Kuhn)
Galactic dark matter ? Oort (1932) dynamics 0.092 visible 0.038
Galactic dark matter Holmberg & Flynn 2000
The strong outlyer is Bahcall, yet we were urged to believe him
Discussion in IAU 117
Schwarschild (1954)
(1959)
Grands instruments : ELT
Group dark matter
NGC 2300 group Mulchaey et al. 1993
It is possible to find ''fossil groups'', thought to be a group merged into an elliptical Ponman et al. (1994, 1996) Koshroshahi et al. (2004)
Burbidge, Burbidge & Prendergast (1960) long series of papers on rotation curves hampered by lack of sensitivity, and hence limited in radial range
Bosma (1978)
Rubin (2003)
WSRT mosaic Braun (2004)
A Matthew effect ?
Exponential Disk (Freeman 1970)
Expect peak at 2.2 scalelengths, discrepancy is seen out to > 10 15 scalelengths
“If you start computing, do not stop thinking...” Rogstad & Shostak (1972) Shostak (1973)
Roberts & Whitehurst (1975) Newton & Emerson (1977) redid M31, and confirmed the flat rotation curve
Effect of resolution M101
Bosma, Allen & Goss (1981)
Roberts & Rots (1973)
Disk stability argument
Hohl (1971)
Even though the stability argument is now disputed, (cf. Athanassoula), the idea of a dark halo slowly gained acceptance
Dark halo : proposed for spirals also Ostriker , Peebles & Yahil (1974)
IC 342
absent
counter Briggs rule
⊗
Crosthwaite et al. 2000, 2001
IAU Symp. 69, 341 (1975)
The warp in M33 Rogstad et al. (1976)
Ferguson et al. (2006)
Kalnajs (1983) Athanassoula et al. (1987)
Salucci & Corbelli 2004 ISO
NFW
Flat rotation curves beyond the optical image Bosma, 1978, 1981a,b
Flat rotation curves beyond the optical image Bosma 1978, 1981a,b also Bosma & Van der Kruit 1979
Oval distortions vs. warps Bosma 1991
Warps : kinematical axes stay ⊥ Ovals : kinematical axes not ⊥
The last point ...matters
Kalnajs 1983 Kent 1986/7 Athanassoula et al.1987 Palunas & Williams 2000
better use HI, since it goes farther out
A Matthew effect ?
Note that this galaxy is NGC 1365 ...
(Vera Rubin is NOT a radioastronomer) Jorsater & Van Moorsel (1996)
A Sicking 1997 Matthew effect ?
Expect peak at 2.2 scalelengths, discrepancy is seen out to > 10 15 scalelengths
Aaronson et al. (1983)
Dwarf spheroidal galaxies
Dwarf spheroidal galaxies Wilkinson et al. (2006)
Central densities : higher in dwarfs ??
Kormendy & Freeman 2004 : IAU Symp. 220
Large scale structure
Large scale structure Supercluster ? Virgocentric infall Voids and filaments Redshift surveys of whole sky Great attractor Bulk flows All this gives Ω ~ 0.2 0.3
Bahcall et al. (1995)
Nature of dark matter ? Dark matter seems here to stay, yet little is known about its nature baryonic components : faint stars in halo machos “missing” hot gas or undetectable cold gas weak interacting massive particle neutrinos cannot cl e tt
Dark Matter in Galaxies The dark matter hypothesis does not sit easy : it is not satisfying to blame everything on “things invisible” hence every now and then there is a “summer of discontent” e.g. MOND, or e.g. dark matter is baryonic after all, or e.g. self interacting dark matter solves the core/cusp problem compare to philosophical problems concerning “society”: “the invisible hand” provided by “market forces” “the solitary walker” in a city relies on “society” for his security, yet “there is no such thing as society” for some
Modified dynamics (MOND)
modify the acceleration at low levels Milgrom 1983
Modified dynamics (MOND)
modify the acceleration at low levels Milgrom 1983
Aguirre et al. (2001) Sanders & McGaugh (2002)
Dark Matter vs. Modified dynamics
Milgrom & Sanders 2006
NGC 3198
MOND : pb. with distance?
Bottema et al. 2002
Dark Matter vs. Modified dynamics Aguirre, 2004, in IAU Symp. 220 “dark matter in galaxies”
“proper” formulation of MOND : TeVeS – Bekenstein (2004)
Direct test for MOND Note the value for a_0 is different than for the nearby spirals !
Neutrinos as dark matter ?
Tremaine & Gunn (1979)
Galactic dark matter Microlensing towards LMC/SMC : no evidence for much baryonic DM Microlensing towards bulge : not much room for NFWlike profile
Tisserand et al. (2006) Bissantz & Gerhard (2002) Hamadache et al. (2006)
Dark matter is “undetectable” gas ? Bosma (2004)
Hoekstra et al.(2002) Bosma 1978
“DM is gas idea” pursued by Pfenniger & Combes (1994)
NGC 5907 halo or accretion ? Morrison et al. (1994) Zheng et al. (1999) NGC 4244 Fry et al. (1999)
Zepf et al. (2000) NICMOS
Found 1 star, should have seen many if IMF normal
NGC 4565 Wu et al. (2002)
Warp could also be due to accretion ?
Nature of the dark matter ??
Fit to EGRET data de Boer et al. 2005 Bergström et al. 2006
Shape of the dark halo Vcq
Elliptical disks ?
For these 2 galaxies, the faint outer structure was missed in the nearIR...
Rix & Zaritsky (1995) FdZ92 : scatter in the TF relation => (1b/a) small
Shape of the dark halo
Sackett et al. 1994
Polar ring A01360801 Schweizer et al. (1983) Initially thought to be round; not anymore...
Shape of the dark halo +0.3 c/a = 0.2 0.1
depends on the gas velocity dispersion, also on warp & projection effects
Merrifield (2004)
Case study : UGC 7321
Uson & Matthews (2003) Matthews & Wood (2003) Pohlen et al. (2004)
something wrong with the fit ...
More work on flaring O'Brien, Bosma & Freeman (in progress)
Axial ratio opt. 16:1 HI 4:1 if image redshifted to z = 1, then only see knots ?
Chain galaxies at higher z Cowie et al. 1995, Dalcanton & Schectman 1996, Elmegreen et al. 2004a,b
Peak at T=6 ?
Chain galaxies fatter by factor ~2 compared to types SdSdm ?
Sagittarius dwarf stream: a round MW halo ?
Ibata et al. (2001) : round halo ? Now much more data: Johnston et al. (2005) argue for oblate shape Helmi (2004) argues for prolate shape
Model degeneracy : maximum disk ?
Verheijen (1997) Athanassoula et al. 1987
Maximum disk in a barred spiral NGC 4123 Weiner et al. (2001)
Maximum disk in a barred spiral
Spiral arm “wiggles” When crossing spiral arms, the positionvelocity diagram from a longslit spectrum will show peculiar velocities. The presence of “wiggles” was taken by some as argument for a “maximum disk”
Buchhorn 1992, cf. Freeman 1991
Spiral arm “wiggles”
Kranz, Slyz & Rix (2001, 2003)
Edgeon galaxies Kregel et al. (2005) conclusion differs from previous study
Velocity dispersions Use locally isothermal disk, then
The disk scale height is known statistically for edgeon galaxies, and can be measured for faceon galaxies (Verheijen 2006)
Bell & De Jong 2001
Stellar mass from models (Kassin et al. 2006)
max. disk built in ? IMF universal ? adiabatic contraction in any case, NFW does not fit data well
Bell & De Jong 2001
Dark Matter in Galaxies A. Bosma Observatoire de Marseille (actually LAM / OAMP) History of the problem (incomplete and perhaps biased) Focus on recent problems in the field a. dark matter in spirals b. core/cusp problem c. dark matter in ellipticals d. galaxy formation & the future
