The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies

K. Schawinski; S. Kaviraj; S. Khochfar; S.-J. Yoon; S.K. Yi; Y.-W. Lee; J.-M. Deharveng; A. Boselli; J. Donas; B. Milliard; T. Barlow; T. Conrow; K. Forster; P.G. Friedman; D.C. Martin; P. Morrissey; M. Seibert; T. Small; T. Wyder; S. Neff; D. Schiminovich; L. Blanchi; T. Heckman; A. Szalay; B. Madore; R.M. Rich

doi:10.1086/516631

The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies

K. Schawinski, S. Kaviraj, S. Khochfar, S.-J. Yoon, S.K. Yi, Y.-W. Lee, J.-M. Deharveng, A. Boselli, J. Donas, B. Milliard, T. Barlow, T. Conrow, K. Forster, P.G. Friedman, D.C. Martin, P. Morrissey, M. Seibert, T. Small, T. Wyder, S. NeffD. Schiminovich, L. Blanchi, T. Heckman, A. Szalay, B. Madore, R.M. Rich

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Abstract

We use GALEX near-UV (NUV ) photometry of a sample of early-type galaxies selected in the SDSS (Sloan Digital Sky Survey) to study the UV color-magnitude relation (CMR). NUV - r color is an excellent tracer of even small amounts (∼1 % mass fraction) of recent (≲1 Gyr) star formation, and so the NUV - r CMR allows us to study the effect of environment on the recent star formation history. We analyze a volume-limited sample of 839 visually inspected early-type galaxies in the redshift range 0.05 <z <0.10 brighter than M of - 21.5 with any possible emission-line or radio-selected active galactic nuclei (AGNs) removed to avoid contamination. We find that contamination by AGN candidates and late-type interlopers highly bias any study of recent star formation in early-type galaxies and that, after removing those, our lower limit to the fraction of massive early-type galaxies showing signs of recent star formation is roughly 30% ± 3%. This suggests that residual star formation is common even among the present day early-type galaxy population. We find that the fraction of UV-bright early-type galaxies is 25% higher in low-density environments. However, the density effect is clear only in the lowest density bin. The blue galaxy fraction for the subsample of the brightest early-type galaxies, however, shows a very strong density dependence, in the sense that the blue galaxy fraction is lower in a higher density region.

Original language	English
Pages (from-to)	512-523
Number of pages	12
Journal	Astrophysical Journal, Supplement Series
Volume	173
Issue number	2
DOIs	https://doi.org/10.1086/516631
Publication status	Published - 1 Dec 2007

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Schawinski, K., Kaviraj, S., Khochfar, S., Yoon, S.-J., Yi, S. K., Lee, Y.-W., Deharveng, J.-M., Boselli, A., Donas, J., Milliard, B., Barlow, T., Conrow, T., Forster, K., Friedman, P. G., Martin, D. C., Morrissey, P., Seibert, M., Small, T., Wyder, T., ... Rich, R. M. (2007). The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies. Astrophysical Journal, Supplement Series, 173(2), 512-523. https://doi.org/10.1086/516631

@article{ae4a2497d78f423b93fe951dedd57fe1,

title = "The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies",

abstract = "We use GALEX near-UV (NUV ) photometry of a sample of early-type galaxies selected in the SDSS (Sloan Digital Sky Survey) to study the UV color-magnitude relation (CMR). NUV - r color is an excellent tracer of even small amounts (∼1 % mass fraction) of recent (≲1 Gyr) star formation, and so the NUV - r CMR allows us to study the effect of environment on the recent star formation history. We analyze a volume-limited sample of 839 visually inspected early-type galaxies in the redshift range 0.05 <z <0.10 brighter than M of - 21.5 with any possible emission-line or radio-selected active galactic nuclei (AGNs) removed to avoid contamination. We find that contamination by AGN candidates and late-type interlopers highly bias any study of recent star formation in early-type galaxies and that, after removing those, our lower limit to the fraction of massive early-type galaxies showing signs of recent star formation is roughly 30% ± 3%. This suggests that residual star formation is common even among the present day early-type galaxy population. We find that the fraction of UV-bright early-type galaxies is 25% higher in low-density environments. However, the density effect is clear only in the lowest density bin. The blue galaxy fraction for the subsample of the brightest early-type galaxies, however, shows a very strong density dependence, in the sense that the blue galaxy fraction is lower in a higher density region.",

author = "K. Schawinski and S. Kaviraj and S. Khochfar and S.-J. Yoon and S.K. Yi and Y.-W. Lee and J.-M. Deharveng and A. Boselli and J. Donas and B. Milliard and T. Barlow and T. Conrow and K. Forster and P.G. Friedman and D.C. Martin and P. Morrissey and M. Seibert and T. Small and T. Wyder and S. Neff and D. Schiminovich and L. Blanchi and T. Heckman and A. Szalay and B. Madore and R.M. Rich",

year = "2007",

month = dec,

day = "1",

doi = "10.1086/516631",

language = "English",

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Schawinski, K, Kaviraj, S, Khochfar, S, Yoon, S-J, Yi, SK, Lee, Y-W, Deharveng, J-M, Boselli, A, Donas, J, Milliard, B, Barlow, T, Conrow, T, Forster, K, Friedman, PG, Martin, DC, Morrissey, P, Seibert, M, Small, T, Wyder, T, Neff, S, Schiminovich, D, Blanchi, L, Heckman, T, Szalay, A, Madore, B & Rich, RM 2007, 'The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies', Astrophysical Journal, Supplement Series, vol. 173, no. 2, pp. 512-523. https://doi.org/10.1086/516631

TY - JOUR

T1 - The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies

AU - Schawinski, K.

AU - Kaviraj, S.

AU - Khochfar, S.

AU - Yoon, S.-J.

AU - Yi, S.K.

AU - Lee, Y.-W.

AU - Deharveng, J.-M.

AU - Boselli, A.

AU - Donas, J.

AU - Milliard, B.

AU - Barlow, T.

AU - Conrow, T.

AU - Forster, K.

AU - Friedman, P.G.

AU - Martin, D.C.

AU - Morrissey, P.

AU - Seibert, M.

AU - Small, T.

AU - Wyder, T.

AU - Neff, S.

AU - Schiminovich, D.

AU - Blanchi, L.

AU - Heckman, T.

AU - Szalay, A.

AU - Madore, B.

AU - Rich, R.M.

PY - 2007/12/1

Y1 - 2007/12/1

N2 - We use GALEX near-UV (NUV ) photometry of a sample of early-type galaxies selected in the SDSS (Sloan Digital Sky Survey) to study the UV color-magnitude relation (CMR). NUV - r color is an excellent tracer of even small amounts (∼1 % mass fraction) of recent (≲1 Gyr) star formation, and so the NUV - r CMR allows us to study the effect of environment on the recent star formation history. We analyze a volume-limited sample of 839 visually inspected early-type galaxies in the redshift range 0.05 <z <0.10 brighter than M of - 21.5 with any possible emission-line or radio-selected active galactic nuclei (AGNs) removed to avoid contamination. We find that contamination by AGN candidates and late-type interlopers highly bias any study of recent star formation in early-type galaxies and that, after removing those, our lower limit to the fraction of massive early-type galaxies showing signs of recent star formation is roughly 30% ± 3%. This suggests that residual star formation is common even among the present day early-type galaxy population. We find that the fraction of UV-bright early-type galaxies is 25% higher in low-density environments. However, the density effect is clear only in the lowest density bin. The blue galaxy fraction for the subsample of the brightest early-type galaxies, however, shows a very strong density dependence, in the sense that the blue galaxy fraction is lower in a higher density region.

AB - We use GALEX near-UV (NUV ) photometry of a sample of early-type galaxies selected in the SDSS (Sloan Digital Sky Survey) to study the UV color-magnitude relation (CMR). NUV - r color is an excellent tracer of even small amounts (∼1 % mass fraction) of recent (≲1 Gyr) star formation, and so the NUV - r CMR allows us to study the effect of environment on the recent star formation history. We analyze a volume-limited sample of 839 visually inspected early-type galaxies in the redshift range 0.05 <z <0.10 brighter than M of - 21.5 with any possible emission-line or radio-selected active galactic nuclei (AGNs) removed to avoid contamination. We find that contamination by AGN candidates and late-type interlopers highly bias any study of recent star formation in early-type galaxies and that, after removing those, our lower limit to the fraction of massive early-type galaxies showing signs of recent star formation is roughly 30% ± 3%. This suggests that residual star formation is common even among the present day early-type galaxy population. We find that the fraction of UV-bright early-type galaxies is 25% higher in low-density environments. However, the density effect is clear only in the lowest density bin. The blue galaxy fraction for the subsample of the brightest early-type galaxies, however, shows a very strong density dependence, in the sense that the blue galaxy fraction is lower in a higher density region.

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U2 - 10.1086/516631

DO - 10.1086/516631

M3 - Article

AN - SCOPUS:39449114004

SN - 0067-0049

VL - 173

SP - 512

EP - 523

JO - Astrophysical Journal, Supplement Series

JF - Astrophysical Journal, Supplement Series

IS - 2

ER -

The effect of environment on the ultraviolet color-magnitude relation of early-type galaxies

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