The low dark matter content of the lenticular galaxy NGC 3998
Abstract
We observed the lenticular galaxy NGC 3998 with the Mitchell Integral-Field Spectrograph and extracted line-of-sight velocity distributions out to three half-light radii. We constructed collisionless orbit models in order to constrain NGC 3998's dark and visible structure, using kinematics from both the Mitchell and SAURON instruments. We find NGC 3998 to be almost axisymmetric, seen nearly face-on with a flattened intrinsic shape – i.e. a face-on fast rotator. We find an I-band mass-to-light ratio of 4.7 +0.32/−0.45 in good agreement with previous spectral fitting results for this galaxy. Our best-fitting orbit model shows a both a bulge and a disc component, with a non-negligible counter-rotating component also evident. We find that relatively little dark matter is needed to model this galaxy, with an inferred dark mass fraction of just 7.1 +8.1/−7.1 percent within one half-light radius.
Citation
Boardman , N F , Weijmans , A , Bosch , R C E V D , Zhu , L , Yildirim , A , Ven , G V D , Cappellari , M , Zeeuw , P T D , Emsellem , E , Krajnović , D & Naab , T 2016 , ' The low dark matter content of the lenticular galaxy NGC 3998 ' Monthly Notices of the Royal Astronomical Society , vol 460 , no. 3 , pp. 3029-3043 . DOI: 10.1093/mnras/stw1187
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Rights
© 2016, The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at mnras.oxfordjournals.org / https://dx.doi.org/10.1093/mnras/stw1187
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