In this work we measure the merger fraction, f_m, of L_B >= L^*_B galaxies in the VVDS-Deep spectroscopic Survey. We define kinematical close pairs as those galaxies with a separation in the sky plane 5h^{-1} kpc < r_p <= 100h^{-1} kpc and a relative velocity Delta v <= 500 km s^{-1} in redshift space. We study f_m in two redshift intervals and for several values of mu, the B-band luminosity ratio of the galaxies in the pair, from 1/2 to 1/10. We take mu >= 1/4 and 1/10 <= mu < 1/4 as major and minor mergers. The fraction of minor mergers for bright galaxies evolves with redshift as a power-law (1+z)^m with index m = -0.4 ± 0.6 for the merger fraction and m = -0.8 ± 0.9 for the merger rate. We split our principal galaxies in red and blue by their rest-frame NUV-r colour, finding that i) f_m is higher for red galaxies, ii) f_m^red does not evolve with z, and iii) f_m^blue evolves dramatically. Our results show that the mass of normal L_B >= L^*_B galaxies has grown ˜ 25% since z ˜ 1 because of minor and major mergers. The relative contribution of the mass growth by merging is ˜ 25% due to minor mergers and ˜ 75% due to major ones. The relative effect of merging is more important for red galaxies, with those subject to 0.6 minor and 0.7 major mergers since z ˜ 1, which leads to a mass growth of ˜ 40% and a size increase by a factor of 2. These results show that minor merging is a significant but not dominant mechanism driving the mass growth of galaxies in the last ˜ 8 Gyr.

The VVDS-Deep Survey: the growth of bright galaxies by minor mergers since z = 1 / C. Lopez-Sanjuan;O. . Fevre;L. . Ravel;O. Cucciati;O. Ilbert;L. Tresse;S. Bardelli;M. Bolzonella;T. Contini;B. Garilli;L. Guzzo;D. Maccagni;H. J. McCracken;Y. Mellier;A. Pollo;D. Vergani;E. Zucca. - STAMPA. - (2011), pp. 232-237. (Intervento presentato al convegno Highlights of Spanish Astrophysics VI tenutosi a Madrid (Spain) nel September 13 - 17, 2010).

The VVDS-Deep Survey: the growth of bright galaxies by minor mergers since z = 1

CUCCIATI, OLGA;
2011

Abstract

In this work we measure the merger fraction, f_m, of L_B >= L^*_B galaxies in the VVDS-Deep spectroscopic Survey. We define kinematical close pairs as those galaxies with a separation in the sky plane 5h^{-1} kpc < r_p <= 100h^{-1} kpc and a relative velocity Delta v <= 500 km s^{-1} in redshift space. We study f_m in two redshift intervals and for several values of mu, the B-band luminosity ratio of the galaxies in the pair, from 1/2 to 1/10. We take mu >= 1/4 and 1/10 <= mu < 1/4 as major and minor mergers. The fraction of minor mergers for bright galaxies evolves with redshift as a power-law (1+z)^m with index m = -0.4 ± 0.6 for the merger fraction and m = -0.8 ± 0.9 for the merger rate. We split our principal galaxies in red and blue by their rest-frame NUV-r colour, finding that i) f_m is higher for red galaxies, ii) f_m^red does not evolve with z, and iii) f_m^blue evolves dramatically. Our results show that the mass of normal L_B >= L^*_B galaxies has grown ˜ 25% since z ˜ 1 because of minor and major mergers. The relative contribution of the mass growth by merging is ˜ 25% due to minor mergers and ˜ 75% due to major ones. The relative effect of merging is more important for red galaxies, with those subject to 0.6 minor and 0.7 major mergers since z ˜ 1, which leads to a mass growth of ˜ 40% and a size increase by a factor of 2. These results show that minor merging is a significant but not dominant mechanism driving the mass growth of galaxies in the last ˜ 8 Gyr.
2011
Highlights of Spanish Astrophysics VI
232
237
The VVDS-Deep Survey: the growth of bright galaxies by minor mergers since z = 1 / C. Lopez-Sanjuan;O. . Fevre;L. . Ravel;O. Cucciati;O. Ilbert;L. Tresse;S. Bardelli;M. Bolzonella;T. Contini;B. Garilli;L. Guzzo;D. Maccagni;H. J. McCracken;Y. Mellier;A. Pollo;D. Vergani;E. Zucca. - STAMPA. - (2011), pp. 232-237. (Intervento presentato al convegno Highlights of Spanish Astrophysics VI tenutosi a Madrid (Spain) nel September 13 - 17, 2010).
C. Lopez-Sanjuan;O. . Fevre;L. . Ravel;O. Cucciati;O. Ilbert;L. Tresse;S. Bardelli;M. Bolzonella;T. Contini;B. Garilli;L. Guzzo;D. Maccagni;H. J. McCracken;Y. Mellier;A. Pollo;D. Vergani;E. Zucca
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/399290
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