A relation between the characteristic stellar ages of galaxies and their intrinsic shapes

Abstract

Stellar population and stellar kinematic studies provide unique but complementary insights into how galaxies build-up their stellar mass and angular momentum1,2,3. A galaxy’s mean stellar age reveals when stars were formed, but provides little constraint on how the galaxy’s mass was assembled. Resolved stellar dynamics4 trace the change in angular momentum due to mergers, but major mergers tend to obscure the effect of earlier interactions5. With the rise of large multi-object integral field spectroscopic surveys, such as SAMI6 and MaNGA7, and single-object integral field spectroscopic surveys (for example, ATLAS3D (ref. 8), CALIFA9, MASSIVE10), it is now feasible to connect a galaxy′s star formation and merger history on the same resolved physical scales, over a large range in galaxy mass, morphology and environment4,11,12. Using the SAMI Galaxy Survey, here we present a combined study of spatially resolved stellar kinematics and global stellar populations. We find a strong correlation of stellar population age with location in the (V/σ, \({\boldsymbol{\epsilon}}_{{\boldsymbol{e}}}\)) diagram that links the ratio of ordered rotation to random motions in a galaxy to its observed ellipticity. For the large majority of galaxies that are oblate rotating spheroids, we find that characteristic stellar age follows the intrinsic ellipticity of galaxies remarkably well.

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Fig. 1: Ratio between stellar ordered rotation and random orbital motion in a galaxy (V/σ)e as a function of total stellar mass.
Fig. 2: Linking stellar dynamics (V/σ)e and observed shape (ellipticity \({{\boldsymbol{\epsilon }}}_{{\bf{e}}}\)) with luminosity-weighted stellar age within one effective radius.
Fig. 3: Luminosity-weighted stellar age in the (V/σ, \({{\boldsymbol{\epsilon }}}_{{\bf{e}}}\)) diagram, split by visual morphological type.
Fig. 4: Intrinsic ellipticity and inclination derived from theoretical predictions and our data from within the (V/σ, \({{\boldsymbol{\epsilon }}}_{{\bf{e}}}\)) diagram.

References

  1. 1.

    Tinsley, B. M. Evolution of the stars and gas in galaxies. Fundam. Cosm. Phys. 5, 287–388 (1980).

    ADS  Google Scholar 

  2. 2.

    Davies, R. L., Efstathiou, G., Fall, S. M., Illingworth, G. & Schechter, P. L. The kinematic properties of faint elliptical galaxies. Astrophys. J. 266, 41–57 (1983).

    ADS  Article  Google Scholar 

  3. 3.

    Bender, R., Burstein, D. & Faber, S. M. Dynamically hot galaxies. II. Global stellar populations. Astrophys. J. 411, 153–169 (1993).

    ADS  Article  Google Scholar 

  4. 4.

    Cappellari, M. Structure and kinematics of early-type galaxies from integral field spectroscopy. Annu. Rev. Astron. Astrophys. 54, 597–665 (2016).

    ADS  Article  Google Scholar 

  5. 5.

    Naab, T. et al. The ATLAS3D project—XXV. Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators. Mon. Not. R. Astron. Soc. 444, 3357–3387 (2014).

    ADS  Article  Google Scholar 

  6. 6.

    Croom, S. M. et al. The Sydney–AAO Multi-object Integral field spectrograph. Mon. Not. R. Astron. Soc. 421, 872–893 (2012).

    ADS  Google Scholar 

  7. 7.

    Bundy, K. et al. Overview of the SDSS-IV MaNGA Survey: mapping nearby galaxies at Apache Point Observatory. Astrophys. J. 798, 7 (2015).

    ADS  Article  Google Scholar 

  8. 8.

    Cappellari, M. et al. The ATLAS3D project—I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria. Mon. Not. R. Astron. Soc. 413, 813–836 (2011).

    ADS  Article  Google Scholar 

  9. 9.

    Sánchez, S. F. et al. CALIFA, the Calar Alto Legacy Integral Field Area survey. I. Survey presentation. Astron. Astrophys. 538, A8 (2012).

    Article  Google Scholar 

  10. 10.

    Ma, C.-P. et al. The MASSIVE Survey. I. A volume-limited integral-field spectroscopic study of the most massive early-type galaxies within 108 Mpc. Astrophys. J. 795, 158 (2014).

    ADS  Article  Google Scholar 

  11. 11.

    van de Sande, J. et al. The SAMI Galaxy Survey: revisiting galaxy classification through high-order stellar kinematics. Astrophys. J. 835, 104 (2017).

    ADS  Article  Google Scholar 

  12. 12.

    Scott, N. et al. The SAMI Galaxy Survey: global stellar populations on the size–mass plane. Mon. Not. R. Astron. Soc. 472, 2833–2855 (2017).

    ADS  Article  Google Scholar 

  13. 13.

    Binney, J. Rotation and anisotropy of galaxies revisited. Mon. Not. R. Astron. Soc. 363, 937–942 (2005).

    ADS  MathSciNet  Article  Google Scholar 

  14. 14.

    Cappellari, M. et al. The SAURON project—X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/σ, ε) diagram with integral-field stellar kinematics. Mon. Not. R. Astron. Soc. 379, 418–444 (2007).

    ADS  Article  Google Scholar 

  15. 15.

    Cappellari, M. et al. The ATLAS3D project—XX. Mass-size and mass-σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function. Mon. Not. R. Astron. Soc. 432, 1862–1893 (2013).

    ADS  Article  Google Scholar 

  16. 16.

    Lange, R. et al. Galaxy And Mass Assembly (GAMA): M R e relations of z = 0 bulges, discs and spheroids. Mon. Not. R. Astron. Soc. 462, 1470–1500 (2016).

    ADS  Article  Google Scholar 

  17. 17.

    Emsellem, E. et al. The ATLAS3D project—III. A census of the stellar angular momentum within the effective radius of early-type galaxies: unveiling the distribution of fast and slow rotators. Mon. Not. R. Astron. Soc. 414, 888–912 (2011).

    ADS  Article  Google Scholar 

  18. 18.

    Foster, C. et al. The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies. Mon. Not. R. Astron. Soc. 472, 966–978 (2017).

    ADS  Article  Google Scholar 

  19. 19.

    Kormendy, J. & Kennicutt, R. C. Jr. Secular evolution and the formation of pseudobulges in disk galaxies. Annu. Rev. Astron. Astrophys. 42, 603–683 (2004).

    ADS  Article  Google Scholar 

  20. 20.

    Seidel, M. K. et al. The BaLROG project—I. Quantifying the influence of bars on the kinematics of nearby galaxies. Mon. Not. R. Astron. Soc. 451, 936–973 (2015).

    ADS  Article  Google Scholar 

  21. 21.

    van Dokkum, P. G. et al. Forming compact massive galaxies. Astrophys. J. 813, 23 (2015).

    ADS  Article  Google Scholar 

  22. 22.

    van der Wel, A. et al. 3D-HST+CANDELS: the evolution of the galaxy size–mass distribution since z = 3. Astrophys. J. 788, 28 (2014).

    ADS  Article  Google Scholar 

  23. 23.

    Newman, A. B., Belli, S. & Ellis, R. S. Discovery of a strongly lensed massive quiescent galaxy at z = 2.636: spatially resolved spectroscopy and indications of rotation. Astrophys. J. Lett. 813, L7 (2015).

    ADS  Article  Google Scholar 

  24. 24.

    Penoyre, Z., Moster, B. P., Sijacki, D. & Genel, S. The origin and evolution of fast and slow rotators in the Illustris simulation. Mon. Not. R. Astron. Soc. 468, 3883–3906 (2017).

    ADS  Article  Google Scholar 

  25. 25.

    Bland-Hawthorn, J. & Gerhard, O. The galaxy in context: structural, kinematic, and integrated properties. Annu. Rev. Astron. Astrophys. 54, 529–596 (2016).

    ADS  Article  Google Scholar 

  26. 26.

    Lee, Y. S. et al. Formation and evolution of the disk system of the Milky Way: [α/Fe] ratios and kinematics of the SEGUE G-dwarf sample. Astrophys. J. 738, 187 (2011).

    ADS  Article  Google Scholar 

  27. 27.

    Sharma, S. et al. Kinematic modeling of the Milky Way using the RAVE and GCS stellar surveys. Astrophys. J. 793, 51 (2014).

    ADS  Article  Google Scholar 

  28. 28.

    Schönrich, R. & Binney, J. Chemical evolution with radial mixing. Mon. Not. R. Astron. Soc. 396, 203–222 (2009).

    ADS  Article  Google Scholar 

  29. 29.

    Förster Schreiber, N. M. et al. The SINS Survey: SINFONI integral field spectroscopy of z ~ 2 star-forming galaxies. Astrophys. J. 706, 1364–1428 (2009).

    ADS  Article  Google Scholar 

  30. 30.

    Tacconi, L. J. et al. Phibss: molecular gas content and scaling relations in z ~ 1–3 massive, main-sequence star-forming galaxies. Astrophys. J. 768, 74 (2013).

    ADS  Article  Google Scholar 

  31. 31.

    Wisnioski, E. et al. The KMOS3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7 < z < 2.7. Astrophys. J. 799, 209 (2015).

    ADS  Article  Google Scholar 

  32. 32.

    Bland-Hawthorn, J. et al. Hexabundles: imaging fiber arrays for low-light astronomical applications. Opt. Express 19, 2649 (2011).

    ADS  Article  Google Scholar 

  33. 33.

    Bryant, J. J., Bland-Hawthorn, J., Fogarty, L. M. R., Lawrence, J. S. & Croom, S. M. Focal ratio degradation in lightly fused hexabundles. Mon. Not. R. Astron. Soc. 438, 869–877 (2014).

    ADS  Article  Google Scholar 

  34. 34.

    Sharp, R. et al. Performance of AAOmega: the AAT multi-purpose fiber-fed spectrograph. Proc. 6269, 62690G (2006).

    Google Scholar 

  35. 35.

    Bryant, J. J. et al. The SAMI Galaxy Survey: instrument specification and target selection. Mon. Not. R. Astron. Soc. 447, 2857–2879 (2015).

    ADS  Article  Google Scholar 

  36. 36.

    Driver, S. P. et al. Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release. Mon. Not. R. Astron. Soc. 413, 971–995 (2011).

    ADS  Article  Google Scholar 

  37. 37.

    Owers, M. S. et al. The SAMI Galaxy Survey: the cluster redshift survey, target selection and cluster properties. Mon. Not. R. Astron. Soc. 468, 1824–1849 (2017).

    ADS  Article  Google Scholar 

  38. 38.

    Sharp, R. et al. The SAMI Galaxy Survey: cubism and covariance, putting round pegs into square holes. Mon. Not. R. Astron. Soc. 446, 1551–1566 (2015).

    ADS  Article  Google Scholar 

  39. 39.

    Allen, J. T. et al. The SAMI Galaxy Survey: early data release. Mon. Not. R. Astron. Soc. 446, 1567–1583 (2015).

    ADS  Article  Google Scholar 

  40. 40.

    Emsellem, E., Monnet, G. & Bacon, R. The multi-Gaussian expansion method: a tool for building realistic photometric and kinematical models of stellar systems I. The formalism. Astron. Astrophys. 285, 739–750 (1994).

    ADS  Google Scholar 

  41. 41.

    Cappellari, M. Efficient multi-Gaussian expansion of galaxies. Mon. Not. R. Astron. Soc. 333, 400–410 (2002).

    ADS  Article  Google Scholar 

  42. 42.

    Scott, N. et al. The SAURON Project—XIV. No escape from V esc: a global and local parameter in early-type galaxy evolution. Mon. Not. R. Astron. Soc. 398, 1835–1857 (2009).

    ADS  Article  Google Scholar 

  43. 43.

    York, D. G. et al. The Sloan Digital Sky Survey: technical summary. Astron. J. 120, 1579–1587 (2000).

    ADS  Article  Google Scholar 

  44. 44.

    Shanks, T. et al. VST ATLAS first science results. Messenger 154, 38–40 (2013).

    ADS  Google Scholar 

  45. 45.

    Cortese, L. et al. The SAMI Galaxy Survey: the link between angular momentum and optical morphology. Mon. Not. R. Astron. Soc. 463, 170–184 (2016).

    ADS  Article  Google Scholar 

  46. 46.

    Taylor, E. N. et al. Galaxy And Mass Assembly (GAMA): stellar mass estimates. Mon. Not. R. Astron. Soc. 418, 1587–1620 (2011).

    ADS  Article  Google Scholar 

  47. 47.

    Chabrier, G. Galactic stellar and substellar initial mass function. Publ. Astron. Soc. Pac. 115, 763–795 (2003).

    ADS  Article  Google Scholar 

  48. 48.

    Cappellari, M. & Emsellem, E. Parametric recovery of line-of-sight velocity distributions from absorption-line spectra of galaxies via penalized likelihood. Publ. Astron. Soc. Pac. 116, 138–147 (2004).

    ADS  Article  Google Scholar 

  49. 49.

    Sánchez-Blázquez, P. et al. Medium-resolution Isaac Newton Telescope library of empirical spectra. Mon. Not. R. Astron. Soc. 371, 703–718 (2006).

    Article  Google Scholar 

  50. 50.

    van de Sande, J. et al. The SAMI Galaxy Survey: revising the fraction of slow rotators in IFS galaxy surveys. Mon. Not. R. Astron. Soc. 472, 1272–1285 (2017).

    ADS  Article  Google Scholar 

  51. 51.

    Schiavon, R. P. Population synthesis in the blue. IV. Accurate model predictions for Lick indices and UBV colors in single stellar populations. Astrophys. J. Suppl. 171, 146–205 (2007).

    ADS  Article  Google Scholar 

  52. 52.

    McDermid, R. M. et al. The ATLAS3D Project—XXX. Star formation histories and stellar population scaling relations of early-type galaxies. Mon. Not. R. Astron. Soc. 448, 3484–3513 (2015).

    ADS  Article  Google Scholar 

  53. 53.

    Green, A. W. et al. The SAMI Galaxy Survey: Data Release One with emission-line physics value-added products. Mon. Not. R. Astron. Soc. 475, 716–734 (2018).

    ADS  Article  Google Scholar 

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Acknowledgements

The SAMI Galaxy Survey is based on observations made at the Anglo-Australian Telescope. The Sydney–Australian Astronomical Observatory Multi-object Integral field spectrograph (SAMI) was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the Sloan Digital Sky Survey, the GAMA Survey and the VST ATLAS Survey. The SAMI Galaxy Survey is funded by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. The SAMI Galaxy Survey website is http://sami-survey.org/. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. J.v.d.S. is funded under Bland-Hawthorn′s Australian Research Council Laureate Fellowship (FL140100278). N.S. acknowledges support of a University of Sydney Postdoctoral Research Fellowship. S.B. acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140101166). M.S.O. acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140100255). J.v.d.S. and N.S. thank all SAMI team members for valuable discussions. A.M.M. is a Hubble Fellow.

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J.v.d.S. and N.S. led the interpretation. J.v.d.S. measured the stellar kinematic parameters from the SAMI Galaxy Survey spectra and wrote the text. N.S. measured the Lick indices from the spectra, and derived the stellar population ages. F.E. measured the structural parameters. All authors contributed to the analysis and interpretation of the data, and contributed to overall team operations, including target catalogue and observing preparation, instrument maintenance, observing at the telescope, writing data reduction and analysis software, managing various pieces of team infrastructure such as the website and data storage systems, and innumerable other tasks critical to the preparation and presentation of a large dataset presented here.

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Correspondence to Jesse van de Sande.

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van de Sande, J., Scott, N., Bland-Hawthorn, J. et al. A relation between the characteristic stellar ages of galaxies and their intrinsic shapes. Nat Astron 2, 483–488 (2018). https://doi.org/10.1038/s41550-018-0436-x

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