The Extended H
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                    Rotation Curve and Mass Distribution of M31

Carignan, C.; Chemin, L.; Huchtmeier, W. K.; Lockman, Felix J.

doi:10.1086/503869

Cited by 146 publications

(194 citation statements)

References 46 publications

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“…It also supports the idea that the ingestion of GCs from accreting dwarf galaxies may provide a significant contribution to the assembly of the globular cluster systems of giant galaxies, as already shown in the case of the Milky Way (Bellazzini et al 2003b). Carignan et al (2006). We have labelled only the clusters, among those labelled in Fig.…”

Section: Clusters In Streamssupporting

confidence: 86%

HST/ACS colour–magnitude diagrams of M 31 globular clusters

Perina

Federici

Bellazzini

et al. 2009

A&A

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Aims. With the aim of increasing the sample of M 31 clusters for which a colour-magnitude diagram is available, we searched the HST archive for ACS images containing objects included in the Revised Bologna Catalogue of M 31 globular clusters . Methods. Sixty-three such objects were found. We used the ACS images to confirm or revise their classification and were able to obtain useful CMDs for 11 old globular clusters and 6 luminous young clusters. We obtained simultaneous estimates of the distance, reddening, and metallicity of old clusters by comparing their observed field-decontaminated CMDs with a grid of template clusters of the Milky Way. We estimated the age of the young clusters by fitting with theoretical isochrones. Results. For the old clusters, we found metallicities in the range −0.4 ≤ [Fe/H] ≤ −1.9. The individual estimates generally agree with existing spectroscopic estimates. At least four of them display a clear blue horizontal branch, indicating ages > ∼ 10 Gyr. All six candidate young clusters are found to have ages <1 Gyr. The photometry of the clusters is made publicly available through a dedicated web page. Conclusions. With the present work the total number of M 31 GCs with reliable optical CMD increases from 35 to 44 for the old clusters, and from 7 to 11 for the young ones. The old clusters show similar characteristics to those of the MW. We discuss the case of the cluster B407, with a metallicity [Fe/H] −0.6 and located at a large projected distance from the centre of M 31 (R p = 19.8 kpc) and from the major axis of the galaxy (Y = 11.3 kpc). Metal-rich globulars at large galactocentric distances are rare both in M 31 and in the Milky Way. B407, in addition, has a velocity in stark contrast with the rotation pattern shared by the bulk of M 31 clusters of similar metallicity. This, along with other empirical evidence, supports the hypothesis that the cluster (together with B403) is physically associated with a substructure in the halo of M 31 that has been interpreted as the relic of a merging event.

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Section: Clusters In Streamssupporting

confidence: 86%

HST/ACS colour–magnitude diagrams of M 31 globular clusters

Perina

Federici

Bellazzini

et al. 2009

A&A

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“…The resulting rotational velocity curve is rising until a maximum of 300 km s −1 , reached at 3 kpc, and then slightly decreases, remaining close to 300 km s −1 in the central regions of interest here. This corresponds to the rotational velocity observed (e.g., Carignan et al 2006). All molecular clouds we aim to reproduce are inside the radius of maximum rotational velocity.…”

Section: Scenario 3: Head-on Collision With M 32supporting

confidence: 79%

Molecular gas in the inner 0.7 kpc-radius ring of M 31

Melchior

Combes

2011

A&A

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The study of the gas kinematic in the central 1.5 kpc × 1.5 kpc region of M 31 has revealed several surprises. The starting point of this investigation was the detection at the IRAM-30 m telescope of molecular gas with very large line splittings up to 260 km s −1 within the beam (∼40 pc). In this region, which is known for its low gas content, we also detect an ionised gas outflow in the circumnuclear region (within 75 pc from the centre) extending to the whole area in X-ray. Relying on atomic, ionised, and molecular gas, we account for most observables with a scenario that assumes that a few hundreds Myr ago, M 31 underwent a frontal collision with M 32, which triggered some star-formation activity in the centre, and this collision explains the special configuration of M 31 with two rings observed at 0.7 kpc and 10 kpc. The inner disc (whose rotation is detected in HI and ionised gas ([NII])) has thus been tilted (inclination: 43 deg, PA: 70 deg) with respect to the main disc (inclination: 77 deg, PA: 35 deg). One of the CO velocity components is compatible with this inner disc, while the second one comes from a tilted ring-like material with 40 deg inclination and PA = −35 deg. The relic star formation estimated by previous works to have occurred more than 100 Myr ago could have been triggered by the collision and could be linked to the outflow detected in the ionised gas. Last, we demonstrate that the amplitude of the line splittings detected in CO centred on the systemic velocity with a relatively high spatial resolution (40 pc) cannot be accounted for by a possible weak bar that is roughly aligned along the minor axis. Although M 31 has a triaxial bulge, there are no bar indicators in the gas component (photometry, no strong skewness of the isovelocities, etc.).

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“…Some papers (e.g. Carignan et al 2006) analyze the extended rotation curve of M 31 using only HI data along the direction of the optical major axis, without considering the possibility of a warped disk. Only very recently Chemin et al (2009) use deep 21-cm survey of the M 31 based on high resolution synthesis observations to model the warp and the rotation curve simultaneously.…”

Section: Introductionmentioning

confidence: 99%

A wide-field H I mosaic of Messier 31

Corbelli

Lorenzoni

Walterbos³

et al. 2010

A&A

163

229

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Aims. We test cosmological models of structure formation using the rotation curve of the nearest spiral galaxy, M 31, determined using a recent deep, full-disk 21-cm imaging survey smoothed to 466 pc resolution. Methods. We fit a tilted ring model to the HI data from 8 to 37 kpc and establish conclusively the presence of a dark halo and its density distribution via dynamical analysis of the rotation curve. Results. The disk of M 31 warps from 25 kpc outwards and becomes more inclined with respect to our line of sight. Newtonian dynamics without a dark matter halo provide a very poor fit to the rotation curve. In the framework of modified Newtonian dynamic (MOND) however the 21-cm rotation curve is well fitted by the gravitational potential traced by the baryonic matter density alone. The inclusion of a dark matter halo with a density profile as predicted by hierarchical clustering and structure formation in a ΛCDM cosmology makes the mass model in newtonian dynamic compatible with the rotation curve data. The dark halo concentration parameter for the best fit is C = 12 and its total mass is 1.2 × 10 12 M . If a dark halo model with a constant-density core is considered, the core radius has to be larger than 20 kpc in order for the model to provide a good fit to the data. We extrapolate the best-fit ΛCDM and constant-density core mass models to very large galactocentric radii, comparable to the size of the dark matter halo. A comparison of the predicted mass with the M 31 mass determined at such large radii using other dynamical tracers, confirms the validity of our results. In particular the ΛCDM dark halo model which best fits the 21-cm data well reproduces the mass of M 31 traced out to 560 kpc. Our best estimate for the total mass of M 31 is 1.3 × 10 12 M , with 12% baryonic fraction and only 6% of the baryons in the neutral gas phase.

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The Extended H i Rotation Curve and Mass Distribution of M31

Cited by 146 publications

References 46 publications

HST/ACS colour–magnitude diagrams of M 31 globular clusters

HST/ACS colour–magnitude diagrams of M 31 globular clusters

Molecular gas in the inner 0.7 kpc-radius ring of M 31

A wide-field H I mosaic of Messier 31

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