high-resolution rotation curves & mass models of little …

Lowell Observatory Workshop 20/June/2012

Se-Heon Oh

High-resolution rotation curves &High-resolution rotation curves &mass models of LITTLE THINGSmass models of LITTLE THINGS

Se-Heon OhSe-Heon Oh1,21,2

1. International Centre for Radio Astronomy Research (ICRAR) The University of Western Australia

2. ARC Centre for All-sky Astrophysics (CAASTRO)(CAASTRO)

with LITTLE THINGS team


Se-Heon Oh

● HI kinematics of galaxiesHI kinematics of galaxies● Dark matter distribution in dwarf galaxiesDark matter distribution in dwarf galaxies● High-resolution mass models of LITTLE THINGSHigh-resolution mass models of LITTLE THINGS● Dark matter distribution in LITTLE THINGSDark matter distribution in LITTLE THINGS● Summary & Future worksSummary & Future works

ContentsContents


Se-Heon Oh

● Dynamical structure : (dark) matter distribution in galaxiesDynamical structure : (dark) matter distribution in galaxies● Interplay between ISM and star formation in galaxies on small Interplay between ISM and star formation in galaxies on small (sub-kpc) scales(sub-kpc) scales● Dynamical information about galaxy evolution : warps, bars Dynamical information about galaxy evolution : warps, bars spiral arms, tidal interaction, high-velocity clouds etc.spiral arms, tidal interaction, high-velocity clouds etc.

HI kinematics of resolved galaxiesHI kinematics of resolved galaxies


Se-Heon Oh

““cusp/core” problem in cusp/core” problem in ΛCDM cosmologyΛCDM cosmology

ObservationsObservationsΛCDM dark-matter-only ΛCDM dark-matter-only simulationssimulations

Moore (1994)Moore (1994)Flores & Primack (1994)Flores & Primack (1994)Navarro, Frenk & White Navarro, Frenk & White (1995)(1995)Navarro, Frenk & White Navarro, Frenk & White (1996)(1996)Moore et al. (1998)Moore et al. (1998)Ghigna et al. (2000)Ghigna et al. (2000)Klypin et al. (2001)Klypin et al. (2001)Power et al. (2002)Power et al. (2002)Navarro et al. (2004)Navarro et al. (2004)Diemand et al. (2008)Diemand et al. (2008)Stadel et al. (2009)Stadel et al. (2009)Navarro et al. (2010)Navarro et al. (2010)etc.etc.

Flores & Primack (1994)Flores & Primack (1994)Moore (1994)Moore (1994)de Blok et al. (2001)de Blok et al. (2001)de Blok & Bosma (2002)de Blok & Bosma (2002)Bolatto et al. (2002)Bolatto et al. (2002)Weldrake et al. (2003)Weldrake et al. (2003)Simon et al. (2003)Simon et al. (2003)Swaters et al. (2003)Swaters et al. (2003)Kuzio de Naray et al. (2006)Kuzio de Naray et al. (2006)Gentile et al. (2007)Gentile et al. (2007)Oh et al. (2008)Oh et al. (2008)Trachternach et al. (2008)Trachternach et al. (2008)de Blok et al. (2008)de Blok et al. (2008)Oh et al. (2011a, b)Oh et al. (2011a, b)etc.etc.

cuspcusp corecore


Se-Heon Oh

● Dynamical structure : (dark) matter distribution in galaxiesDynamical structure : (dark) matter distribution in galaxies● Interplay between ISM and star formation in galaxies on Interplay between ISM and star formation in galaxies on small (sub-kpc) scalessmall (sub-kpc) scales● Dynamical information about galaxy evolution : warps, bars Dynamical information about galaxy evolution : warps, bars spiral arms, tidal interaction, high-velocity clouds etc.spiral arms, tidal interaction, high-velocity clouds etc.

HI kinematics of resolved galaxiesHI kinematics of resolved galaxies


Se-Heon Oh

● N-body+SPH tree-code GASOLINE● Flat Λ-dominated cosmology● Baryonic processes are included, such as - gas cooling - cosmic UV field heating - star formation - SN-driven gas outflows● ~3.3 million particles within the virial radius at z = 0● DM ~ 1.6×104 M ⦿ ; gas particle ~ 3.3×103 M

⦿

● The force resolution (gravitational softening) ~ 86 pc

HI 21cm 3.6 micron

High-resolution SPH+High-resolution SPH+ΛCDM simulations of ΛCDM simulations of dwarf galaxies dwarf galaxies (Governato et al. 2010; 2012)(Governato et al. 2010; 2012)


Se-Heon Oh

Simulations vs. ObservationsSimulations vs. Observations

Rotation curve shape DM density profiles

Radius

Radius

Rotation velocityDM

density

Radius

Oh et al. (2011)

cusps α ~ -1.0

● scaled at R0.3 where dlogV/dlogR = 0.3.


Se-Heon Oh

LITTLE THINGSLITTLE THINGS((LLocal ocal IIrregulars rregulars TThat hat TTrace race LLuminosity uminosity EExtremes xtremes

TThe he HIHI NNearby earby GGalaxy alaxy SSurvey)urvey)

- THINGS-like (~6”; < 5.2 km/s) high-resolution VLA HI 21cm survey (B+C+D; 376 hours) for 41 nearby (< 10 Mpc) dwarf (dIm, BCD) galaxies

- Commensality with Spitzer (+ Herschel) optical, GALEX uv, CO data etc.)- VLA observations ended in 2008- Further observations with EVLA, CARMA, APEX etc.

LITTLE THINGSLITTLE THINGS


Se-Heon Oh

- What regulates star formation in dwarf galaxies?- What is the relative importance of sequential triggering for star formation in dwarf galaxies?- How (dark) matter is distributed in dwarf galaxies?- What is the relative importance of triggering by random turbulence compression in dwarf galaxies?- What is happening in the far outer parts of dwarf galaxies?- What happens to the star formation process at breaks in the exponential light profiles?- What happens in Blue Compact Dwarf (BCD) galaxies?

LITTLE THINGS scienceLITTLE THINGS science


Se-Heon Oh

LITTLE THINGS sampleLITTLE THINGS sample

CVnIdwA DDO 43 DDO 46 DDO 47 DDO 50 DDO 52 DDO 53 DDO 63 DDO 69 DDO 70

DDO 75 DDO 87 DDO 101 DDO 126 DDO 133 DDO 154 DDO 155 DDO 165 DDO 167 DDO 168

DDO 187 DDO 210 DDO 216 F564-V3 IC 10 IC 1613 LGS3 M81dwA NGC 1569 Mrk 178

NGC 2366 NGC 3738 NGC 4163 NGC 4214 NGC 6822 SagDIG UGC 8508 WLM Haro 29 Haro 36

VIIZw 403


Se-Heon Oh

LITTLE THINGS sampleLITTLE THINGS sample

CVnIdwA DDO 43 DDO 46 DDO 47 DDO 50 DDO 52 DDO 53 DDO 63 DDO 69 DDO 70

DDO 75 DDO 87 DDO 101 DDO 126 DDO 133 DDO 154 DDO 155 DDO 165 DDO 167 DDO 168

DDO 187 DDO 210 DDO 216 F564-V3 IC 10 IC 1613 LGS3 M81dwA NGC 1569 Mrk 178

NGC 2366 NGC 3738 NGC 4163 NGC 4214 NGC 6822 SagDIG UGC 8508 WLM Haro 29 Haro 36

VIIZw 403

`


Se-Heon Oh

2 kpc

DDO 168 DDO 101 DDO 126 DDO 168DDO 168

DDO 46 F564-V3 DDO 52 DDO 43 DDO 168

DDO 70 NGC 2366 DDO 50 DDO 63 DDO 53 DDO 154

NGC 1569 DDO 168 DDO 168 NGC 4214 NGC 3738 DDO 168

UGC 8508

DDO 47

DDO 168 Cvn I dwA DDO 87

UGC 8508

IC 10

WLMDDO 210 IC 1613

Haro 29

DDO 133

NGC 2366

DDO 216

HI images of 27 LITTLE THINGSHI images of 27 LITTLE THINGS

3 kpc

X 2


Se-Heon Oh

DDO 168 DDO 101 DDO 168

DDO 43 DDO 47

DDO 210 WLM IC 1613

DDO 126

Haro 29

UGC 8508

DDO 46 F564-V3 DDO 52

DDO 133


NGC 1569 NGC 4214 NGC 3738

IC 10 Cvn I dwA

DDO 101

DDO 87

UGC 8508

IC 10

DDO 216

DDO 210 WLM IC 1613

3 kpc



Se-Heon Oh

2 kpc

DDO 168 DDO 101 DDO 126 DDO 168DDO 168

DDO 46 F564-V3 DDO 52 DDO 43 DDO 168


NGC 1569 DDO 168 DDO 168 NGC 4214 NGC 3738 DDO 168

UGC 8508

DDO 47

DDO 168 Cvn I dwA DDO 87

UGC 8508

IC 10

WLMDDO 210 IC 1613

Haro 29

DDO 133

NGC 2366

DDO 216

3 kpc



Se-Heon Oh

DDO 168 DDO 101 DDO 168 UGC 8508DDO 126

Haro 29

DDO 46 F564-V3 DDO 52 DDO 43

DDO 133

DDO 47


NGC 1569 DDO 210 WLM NGC 4214 NGC 3738 IC 1613

DDO 168IC 10 Cvn I dwA DDO 87IC 10 Cvn I dwA

DDO 70 NGC 2366

DDO 216

DDO 43

NGC 4214DDO 210 WLM IC 1613

DDO 154

DDO 47

UGC 8508

IRAC1 images of 27 LITTLE THINGSIRAC1 images of 27 LITTLE THINGS

3 kpc


Se-Heon Oh

I. DataI. Data

+

Tilted-ring models

● Fit tilted-ring models to 2-D velocity fields(e.g., Rogstad et al. 1974; “rotcur”

in GIPSY)

● Suited for well-resolved galaxies with moderate inclinations


Se-Heon Oh

II. Rotation curves II. Rotation curves & Asymmetric drift correction& Asymmetric drift correction

- Gas drift correction (mainly) for the outer regions (Bureau & Carignan 2002)

● Tilted-ring models+

● Asymmetric drift correction

- Fit tilted-ring models to 2-D velocity field (Rogstad et al. 1974; e.g., ‘rotcur’ in GIPSY)


Se-Heon Oh

III. Position-velocity diagramIII. Position-velocity diagram

` `


Se-Heon Oh

III. Mass models of baryonsIII. Mass models of baryonsstars

TR m

odelsgas

++


Se-Heon Oh

IV. Decomposition of baryonic disk IV. Decomposition of baryonic disk and dark matter haloand dark matter halo

Mass modelling of 27 LITTLE THINGS dwarf galaxies using VLA HI data, Spitzer 3.6 micron and ancilliary optical images


Se-Heon Oh

Comparison with THINGS + SimulationsComparison with THINGS + Simulations


Radius

Radius

Rotation velocityDM

density

RadiusOh et al. (2011)


Se-Heon Oh


Radius

Radius

Rotation velocityDM

density

RadiusOh et al. in prep.



Se-Heon Oh

Comparison with THINGS + simulationsComparison with THINGS + simulations

● The rotation curves are scaled with respect to the V0.3 at R0.3 where dlogV/dlogR = 0.3.

● The scaled rotation curves rise too slowly to match the cuspy CDM halos.

●Instead, they are mostly consistent with core-like pseudo isothermal halo models showing a linear increase in the inner rotation curves.

Rotation curve shape

Radius

Rotation velocity


Se-Heon Oh

● The mean value of the slopes of 17 L.T. Galaxies except 5 THINGS dwarfs, α= −0.40 ± 0.07 is consistent with the value of α = −0.29 ± 0.07 found from 7 THINGS dwarf galaxies in Oh et al. (2011).

● This is in contrast with the steep slope of α -1.0 predicted from ∼ΛCDM (DM only) simulations.

● The core-like DM distributions of L.T. Galaxies are similar to those of new simulations which include baryonic feedback processes.

DM density profiles

cusps α ~ -1.0

DM

density

Radius



Se-Heon Oh

Slope vs. Stellar MassSlope vs. Stellar Mass

Inner density slope of D

M profile Stellar Mass See Governato et al. 2012


Se-Heon Oh

SummarySummary

● High-quality multi-λ data (VLA HI, Spitzer 3.6μm and optical data) from LITTLE THINGS significantly reduce the observational uncertainties and allow us to derive a more accurate dark matter distribution

● The rotation curve shape and inner mass density slopes of LITTLE THINGS are mostly consistent with those of new simulations including baryonic feedback processes as well as THINGS dwarf galaxies.

● The mean of inner density slopes of 24 THINGS+LITTLE THINGS dwarf galaxies is α=−0.37±0.13 which is consistent with α=−0.2±0.2 found from LSB galaxies (de Blok et al. 2002) but significantly deviating from ~ −1.0 predicted from dark-matter-only ΛCDM simulations

● The central DM distribution of 24 dwarf galaxies from LITLE THINGS + THINGS appears to be cored.

● Low mass dwarf galaxies will be the key for the complete discussion of the cusp/core controversy.

high-resolution rotation curves & mass models of little …

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