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Comparing PyMorph and SDSS photometry. II.: The differences are more than semantics and are not dominated by intracluster light

Comparing PyMorph and SDSS photometry. II.: The differences are more than semantics and are not dominated by intracluster light
Comparing PyMorph and SDSS photometry. II.: The differences are more than semantics and are not dominated by intracluster light
The Sloan Digital Sky Survey (SDSS) pipeline photometry underestimates the brightnesses of the most luminous galaxies. This is mainly because (i) the SDSS overestimates the sky background, and (ii) single-component or two-component Sérsic-based models better fit the surface brightness profile of galaxies, especially at high luminosities, than the de Vaucouleurs model used by the SDSS pipeline. We use the pymorph photometric reductions to isolate effect (ii) and show that it is the same in the full sample as in small group environments, and for satellites in the most massive clusters as well. None of these are expected to be significantly affected by intracluster light (ICL). We only see an additional effect for centrals in the most massive haloes, but we argue that even this is not dominated by ICL. Hence, for the vast majority of galaxies, the differences between pymorph and SDSS pipeline photometry cannot be ascribed to the semantics of whether or not one includes the ICL when describing the stellar mass of massive galaxies. Rather, they likely reflect differences in star formation or assembly histories. Failure to account for the SDSS underestimate has significantly biased most previous estimates of the SDSS luminosity and stellar mass functions, and therefore halo model estimates of the z ∼ 0.1 relation between the mass of a halo and that of the galaxy at its centre. We also show that when one studies correlations, at fixed group mass, with a quantity that was not used to define the groups, then selection effects appear. We show why such effects arise and should not be mistaken for physical effects.
0035-8711
2569-2581
Bernardi, M.
8408e06c-ce0c-4052-a938-f42c3ad17627
Fischer, J.-L.
05c5a104-756d-40da-9631-81b07200e593
Sheth, R.K.
94b203a4-bea4-461b-a237-14d548264e15
Meert, A.
acca7405-016e-428c-afd3-711efb79f571
Huertas-Company, M.
0a864d45-6e9b-43cc-9db8-c25b0bb633ea
Shankar, F.
b10c91e4-85cd-4394-a18a-d4f049fd9cdb
Vikram, V.
5f868b6a-86ba-4fed-8fc4-58384dbf3729
Bernardi, M.
8408e06c-ce0c-4052-a938-f42c3ad17627
Fischer, J.-L.
05c5a104-756d-40da-9631-81b07200e593
Sheth, R.K.
94b203a4-bea4-461b-a237-14d548264e15
Meert, A.
acca7405-016e-428c-afd3-711efb79f571
Huertas-Company, M.
0a864d45-6e9b-43cc-9db8-c25b0bb633ea
Shankar, F.
b10c91e4-85cd-4394-a18a-d4f049fd9cdb
Vikram, V.
5f868b6a-86ba-4fed-8fc4-58384dbf3729

Bernardi, M., Fischer, J.-L., Sheth, R.K., Meert, A., Huertas-Company, M., Shankar, F. and Vikram, V. (2017) Comparing PyMorph and SDSS photometry. II.: The differences are more than semantics and are not dominated by intracluster light. Monthly Notices of the Royal Astronomical Society, 468 (3), 2569-2581.

Record type: Article

Abstract

The Sloan Digital Sky Survey (SDSS) pipeline photometry underestimates the brightnesses of the most luminous galaxies. This is mainly because (i) the SDSS overestimates the sky background, and (ii) single-component or two-component Sérsic-based models better fit the surface brightness profile of galaxies, especially at high luminosities, than the de Vaucouleurs model used by the SDSS pipeline. We use the pymorph photometric reductions to isolate effect (ii) and show that it is the same in the full sample as in small group environments, and for satellites in the most massive clusters as well. None of these are expected to be significantly affected by intracluster light (ICL). We only see an additional effect for centrals in the most massive haloes, but we argue that even this is not dominated by ICL. Hence, for the vast majority of galaxies, the differences between pymorph and SDSS pipeline photometry cannot be ascribed to the semantics of whether or not one includes the ICL when describing the stellar mass of massive galaxies. Rather, they likely reflect differences in star formation or assembly histories. Failure to account for the SDSS underestimate has significantly biased most previous estimates of the SDSS luminosity and stellar mass functions, and therefore halo model estimates of the z ∼ 0.1 relation between the mass of a halo and that of the galaxy at its centre. We also show that when one studies correlations, at fixed group mass, with a quantity that was not used to define the groups, then selection effects appear. We show why such effects arise and should not be mistaken for physical effects.

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Comparing PyMorph and SDSS photometry. II. - Accepted Manuscript
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Accepted/In Press date: 15 March 2017
e-pub ahead of print date: 17 March 2017
Published date: July 2017
Additional Information: Arxiv record 1702.08527 Author Shankar confirms AM copy.
Organisations: Astronomy Group

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Local EPrints ID: 411941
URI: https://eprints.soton.ac.uk/id/eprint/411941
ISSN: 0035-8711
PURE UUID: 3bc5c680-651d-477c-bc10-a1b8572b601a

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Date deposited: 30 Jun 2017 16:31
Last modified: 13 Mar 2019 19:53

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