A Critical Assessment of Stellar Mass Measurement Methods

Bahram Mobasher, Tomas Dahlen, Henry C. Ferguson, V. Acquaviva, Guillermo Barro, Steven L. Finkelstein, Adriano Fontana, Ruth Gruetzbauch, Seth Johnson, Yu Lu, Casey J. Papovich, Janine Pforr, Janine Pforr, Rachel S. Somerville, Tommy Wiklind, S. Wuyts, Matthew L. N. Ashby, Eric Bell, Christopher J. Conselice, Mark E. DickinsonSandra M. Faber, Giovanni Fazio, Kristian Finlator, Audrey Galametz, Eric Gawiser, Mauro Giavalisco, Andrea Grazian, Norman A. Grogin, Yicheng Guo, Nimish Hathi, Dale Kocevski, Anton M. Koekemoer, David C. Koo, Jeffrey A. Newman, Naveen Reddy, Paola Santini, Risa H. Wechsler

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Abstract

This is the second paper in a series aimed at investigating the main sources of uncertainty in measuring the observable parameters in galaxies from their spectral energy distributions (SEDs). In the first paper we presented a detailed account of the photometric redshift measurements and an error analysis of this process. In this paper we perform a comprehensive study of the main sources of random and systematic error in stellar mass estimates for galaxies, and their relative contributions to the associated error budget. Since there is no prior knowledge of the stellar mass of galaxies (unlike their photometric redshifts), we use mock galaxy catalogs with simulated multi-waveband photometry and known redshift, stellar mass, age and extinction for individual galaxies. The multi-waveband photometry for the simulated galaxies were generated in 13 filters spanning from U-band to mid-infrared wavelengths. Given different parameters affecting stellar mass measurement (photometric signal-to-noise ratios (S/N), SED fitting errors and systematic effects), the inherent degeneracies and correlated errors, we formulated different simulated galaxy catalogs to quantify these effects individually. For comparison, we also generated catalogs based on observed photometric data of real galaxies in the Great Observatories Origins Deep Survey-South field, spanning the same passbands. The simulated and observed catalogs were provided to a number of teams within the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey collaboration to estimate the stellar masses for individual galaxies. A total of 11 teams participated, with different combinations of stellar mass measurement codes/methods, population synthesis models, star formation histories, extinction and age. For each simulated galaxy, the differences between the input stellar masses, Minput, and those estimated by each team, Mest, is defined as ${\rm{\Delta }}\mathrm{log}(M)\equiv \mathrm{log}({M}_{\mathrm{estimated}})-\mathrm{log}({M}_{\mathrm{input}})$, and used to identify the most fundamental parameters affecting stellar mass estimate in galaxies, with the following results. (1) No significant bias in Δ log(M) was found among different codes, with all having comparable scatter ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.136$ dex). The estimated stellar mass values are seriously affected by low photometric S/N, with the rms scatter increasing for galaxies with ${H}_{\mathrm{AB}}\gt 26$ mag; (2) A source of error contributing to the scatter in Δ log(M) is found to be due to photometric uncertainties (0.136 dex) and low resolution in age and extinction grids when generating the SED templates; (3) The median of stellar masses among different methods provides a stable measure of the mass associated with any given galaxy ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.142$ dex); (4) The Δ log(M) values are strongly correlated with deviations in age (defined as the difference between the estimated and expected values), with a weaker correlation with extinction; (5) The rms scatter in the estimated stellar masses due to free parameters (after fixing redshifts and initial mass function) are quantified and found to be $\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.110$ dex; (6) Using the observed data, we studied the sensitivity of stellar masses to both the population synthesis codes and inclusion of nebular emission lines and found them to affect the stellar mass by 0.2 and 0.3 dex respectively.
Original languageEnglish
JournalAstrophysical Journal
Volume808
Issue number1
Early online date23 Jul 2015
DOIs
Publication statusPublished - 23 Jul 2015

Fingerprint

measurement method
stellar mass
galaxies
catalogs
extinction
spectral energy distribution
photometry
estimates
random errors
energy
error analysis
synthesis
systematic errors
budgets
fixing
star formation
observatories
signal-to-noise ratio
signal to noise ratios
templates

Keywords

  • galaxies: distances and redshifts
  • galaxies: high-redshift
  • galaxies: photometry
  • surveys

Cite this

Mobasher, B., Dahlen, T., Ferguson, H. C., Acquaviva, V., Barro, G., Finkelstein, S. L., ... Wechsler, R. H. (2015). A Critical Assessment of Stellar Mass Measurement Methods. Astrophysical Journal, 808(1). https://doi.org/10.1088/0004-637X/808/1/101

A Critical Assessment of Stellar Mass Measurement Methods. / Mobasher, Bahram ; Dahlen, Tomas; Ferguson, Henry C.; Acquaviva, V.; Barro, Guillermo; Finkelstein, Steven L.; Fontana, Adriano ; Gruetzbauch, Ruth; Johnson, Seth; Lu, Yu; Papovich, Casey J.; Pforr, Janine; Pforr, Janine; Somerville, Rachel S.; Wiklind, Tommy; Wuyts, S.; Ashby, Matthew L. N.; Bell, Eric; Conselice, Christopher J.; Dickinson, Mark E.; Faber, Sandra M.; Fazio, Giovanni; Finlator, Kristian; Galametz, Audrey; Gawiser, Eric; Giavalisco, Mauro; Grazian, Andrea; Grogin, Norman A.; Guo, Yicheng; Hathi, Nimish; Kocevski, Dale; Koekemoer, Anton M.; Koo, David C.; Newman, Jeffrey A.; Reddy, Naveen; Santini, Paola; Wechsler, Risa H.

In: Astrophysical Journal, Vol. 808, No. 1, 23.07.2015.

Research output: Contribution to journalArticle

Mobasher, B, Dahlen, T, Ferguson, HC, Acquaviva, V, Barro, G, Finkelstein, SL, Fontana, A, Gruetzbauch, R, Johnson, S, Lu, Y, Papovich, CJ, Pforr, J, Pforr, J, Somerville, RS, Wiklind, T, Wuyts, S, Ashby, MLN, Bell, E, Conselice, CJ, Dickinson, ME, Faber, SM, Fazio, G, Finlator, K, Galametz, A, Gawiser, E, Giavalisco, M, Grazian, A, Grogin, NA, Guo, Y, Hathi, N, Kocevski, D, Koekemoer, AM, Koo, DC, Newman, JA, Reddy, N, Santini, P & Wechsler, RH 2015, 'A Critical Assessment of Stellar Mass Measurement Methods', Astrophysical Journal, vol. 808, no. 1. https://doi.org/10.1088/0004-637X/808/1/101
Mobasher B, Dahlen T, Ferguson HC, Acquaviva V, Barro G, Finkelstein SL et al. A Critical Assessment of Stellar Mass Measurement Methods. Astrophysical Journal. 2015 Jul 23;808(1). https://doi.org/10.1088/0004-637X/808/1/101
Mobasher, Bahram ; Dahlen, Tomas ; Ferguson, Henry C. ; Acquaviva, V. ; Barro, Guillermo ; Finkelstein, Steven L. ; Fontana, Adriano ; Gruetzbauch, Ruth ; Johnson, Seth ; Lu, Yu ; Papovich, Casey J. ; Pforr, Janine ; Pforr, Janine ; Somerville, Rachel S. ; Wiklind, Tommy ; Wuyts, S. ; Ashby, Matthew L. N. ; Bell, Eric ; Conselice, Christopher J. ; Dickinson, Mark E. ; Faber, Sandra M. ; Fazio, Giovanni ; Finlator, Kristian ; Galametz, Audrey ; Gawiser, Eric ; Giavalisco, Mauro ; Grazian, Andrea ; Grogin, Norman A. ; Guo, Yicheng ; Hathi, Nimish ; Kocevski, Dale ; Koekemoer, Anton M. ; Koo, David C. ; Newman, Jeffrey A. ; Reddy, Naveen ; Santini, Paola ; Wechsler, Risa H. / A Critical Assessment of Stellar Mass Measurement Methods. In: Astrophysical Journal. 2015 ; Vol. 808, No. 1.
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abstract = "This is the second paper in a series aimed at investigating the main sources of uncertainty in measuring the observable parameters in galaxies from their spectral energy distributions (SEDs). In the first paper we presented a detailed account of the photometric redshift measurements and an error analysis of this process. In this paper we perform a comprehensive study of the main sources of random and systematic error in stellar mass estimates for galaxies, and their relative contributions to the associated error budget. Since there is no prior knowledge of the stellar mass of galaxies (unlike their photometric redshifts), we use mock galaxy catalogs with simulated multi-waveband photometry and known redshift, stellar mass, age and extinction for individual galaxies. The multi-waveband photometry for the simulated galaxies were generated in 13 filters spanning from U-band to mid-infrared wavelengths. Given different parameters affecting stellar mass measurement (photometric signal-to-noise ratios (S/N), SED fitting errors and systematic effects), the inherent degeneracies and correlated errors, we formulated different simulated galaxy catalogs to quantify these effects individually. For comparison, we also generated catalogs based on observed photometric data of real galaxies in the Great Observatories Origins Deep Survey-South field, spanning the same passbands. The simulated and observed catalogs were provided to a number of teams within the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey collaboration to estimate the stellar masses for individual galaxies. A total of 11 teams participated, with different combinations of stellar mass measurement codes/methods, population synthesis models, star formation histories, extinction and age. For each simulated galaxy, the differences between the input stellar masses, Minput, and those estimated by each team, Mest, is defined as ${\rm{\Delta }}\mathrm{log}(M)\equiv \mathrm{log}({M}_{\mathrm{estimated}})-\mathrm{log}({M}_{\mathrm{input}})$, and used to identify the most fundamental parameters affecting stellar mass estimate in galaxies, with the following results. (1) No significant bias in Δ log(M) was found among different codes, with all having comparable scatter ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.136$ dex). The estimated stellar mass values are seriously affected by low photometric S/N, with the rms scatter increasing for galaxies with ${H}_{\mathrm{AB}}\gt 26$ mag; (2) A source of error contributing to the scatter in Δ log(M) is found to be due to photometric uncertainties (0.136 dex) and low resolution in age and extinction grids when generating the SED templates; (3) The median of stellar masses among different methods provides a stable measure of the mass associated with any given galaxy ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.142$ dex); (4) The Δ log(M) values are strongly correlated with deviations in age (defined as the difference between the estimated and expected values), with a weaker correlation with extinction; (5) The rms scatter in the estimated stellar masses due to free parameters (after fixing redshifts and initial mass function) are quantified and found to be $\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.110$ dex; (6) Using the observed data, we studied the sensitivity of stellar masses to both the population synthesis codes and inclusion of nebular emission lines and found them to affect the stellar mass by 0.2 and 0.3 dex respectively.",
keywords = "galaxies: distances and redshifts, galaxies: high-redshift, galaxies: photometry, surveys",
author = "Bahram Mobasher and Tomas Dahlen and Ferguson, {Henry C.} and V. Acquaviva and Guillermo Barro and Finkelstein, {Steven L.} and Adriano Fontana and Ruth Gruetzbauch and Seth Johnson and Yu Lu and Papovich, {Casey J.} and Janine Pforr and Janine Pforr and Somerville, {Rachel S.} and Tommy Wiklind and S. Wuyts and Ashby, {Matthew L. N.} and Eric Bell and Conselice, {Christopher J.} and Dickinson, {Mark E.} and Faber, {Sandra M.} and Giovanni Fazio and Kristian Finlator and Audrey Galametz and Eric Gawiser and Mauro Giavalisco and Andrea Grazian and Grogin, {Norman A.} and Yicheng Guo and Nimish Hathi and Dale Kocevski and Koekemoer, {Anton M.} and Koo, {David C.} and Newman, {Jeffrey A.} and Naveen Reddy and Paola Santini and Wechsler, {Risa H.}",
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T1 - A Critical Assessment of Stellar Mass Measurement Methods

AU - Mobasher, Bahram

AU - Dahlen, Tomas

AU - Ferguson, Henry C.

AU - Acquaviva, V.

AU - Barro, Guillermo

AU - Finkelstein, Steven L.

AU - Fontana, Adriano

AU - Gruetzbauch, Ruth

AU - Johnson, Seth

AU - Lu, Yu

AU - Papovich, Casey J.

AU - Pforr, Janine

AU - Pforr, Janine

AU - Somerville, Rachel S.

AU - Wiklind, Tommy

AU - Wuyts, S.

AU - Ashby, Matthew L. N.

AU - Bell, Eric

AU - Conselice, Christopher J.

AU - Dickinson, Mark E.

AU - Faber, Sandra M.

AU - Fazio, Giovanni

AU - Finlator, Kristian

AU - Galametz, Audrey

AU - Gawiser, Eric

AU - Giavalisco, Mauro

AU - Grazian, Andrea

AU - Grogin, Norman A.

AU - Guo, Yicheng

AU - Hathi, Nimish

AU - Kocevski, Dale

AU - Koekemoer, Anton M.

AU - Koo, David C.

AU - Newman, Jeffrey A.

AU - Reddy, Naveen

AU - Santini, Paola

AU - Wechsler, Risa H.

PY - 2015/7/23

Y1 - 2015/7/23

N2 - This is the second paper in a series aimed at investigating the main sources of uncertainty in measuring the observable parameters in galaxies from their spectral energy distributions (SEDs). In the first paper we presented a detailed account of the photometric redshift measurements and an error analysis of this process. In this paper we perform a comprehensive study of the main sources of random and systematic error in stellar mass estimates for galaxies, and their relative contributions to the associated error budget. Since there is no prior knowledge of the stellar mass of galaxies (unlike their photometric redshifts), we use mock galaxy catalogs with simulated multi-waveband photometry and known redshift, stellar mass, age and extinction for individual galaxies. The multi-waveband photometry for the simulated galaxies were generated in 13 filters spanning from U-band to mid-infrared wavelengths. Given different parameters affecting stellar mass measurement (photometric signal-to-noise ratios (S/N), SED fitting errors and systematic effects), the inherent degeneracies and correlated errors, we formulated different simulated galaxy catalogs to quantify these effects individually. For comparison, we also generated catalogs based on observed photometric data of real galaxies in the Great Observatories Origins Deep Survey-South field, spanning the same passbands. The simulated and observed catalogs were provided to a number of teams within the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey collaboration to estimate the stellar masses for individual galaxies. A total of 11 teams participated, with different combinations of stellar mass measurement codes/methods, population synthesis models, star formation histories, extinction and age. For each simulated galaxy, the differences between the input stellar masses, Minput, and those estimated by each team, Mest, is defined as ${\rm{\Delta }}\mathrm{log}(M)\equiv \mathrm{log}({M}_{\mathrm{estimated}})-\mathrm{log}({M}_{\mathrm{input}})$, and used to identify the most fundamental parameters affecting stellar mass estimate in galaxies, with the following results. (1) No significant bias in Δ log(M) was found among different codes, with all having comparable scatter ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.136$ dex). The estimated stellar mass values are seriously affected by low photometric S/N, with the rms scatter increasing for galaxies with ${H}_{\mathrm{AB}}\gt 26$ mag; (2) A source of error contributing to the scatter in Δ log(M) is found to be due to photometric uncertainties (0.136 dex) and low resolution in age and extinction grids when generating the SED templates; (3) The median of stellar masses among different methods provides a stable measure of the mass associated with any given galaxy ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.142$ dex); (4) The Δ log(M) values are strongly correlated with deviations in age (defined as the difference between the estimated and expected values), with a weaker correlation with extinction; (5) The rms scatter in the estimated stellar masses due to free parameters (after fixing redshifts and initial mass function) are quantified and found to be $\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.110$ dex; (6) Using the observed data, we studied the sensitivity of stellar masses to both the population synthesis codes and inclusion of nebular emission lines and found them to affect the stellar mass by 0.2 and 0.3 dex respectively.

AB - This is the second paper in a series aimed at investigating the main sources of uncertainty in measuring the observable parameters in galaxies from their spectral energy distributions (SEDs). In the first paper we presented a detailed account of the photometric redshift measurements and an error analysis of this process. In this paper we perform a comprehensive study of the main sources of random and systematic error in stellar mass estimates for galaxies, and their relative contributions to the associated error budget. Since there is no prior knowledge of the stellar mass of galaxies (unlike their photometric redshifts), we use mock galaxy catalogs with simulated multi-waveband photometry and known redshift, stellar mass, age and extinction for individual galaxies. The multi-waveband photometry for the simulated galaxies were generated in 13 filters spanning from U-band to mid-infrared wavelengths. Given different parameters affecting stellar mass measurement (photometric signal-to-noise ratios (S/N), SED fitting errors and systematic effects), the inherent degeneracies and correlated errors, we formulated different simulated galaxy catalogs to quantify these effects individually. For comparison, we also generated catalogs based on observed photometric data of real galaxies in the Great Observatories Origins Deep Survey-South field, spanning the same passbands. The simulated and observed catalogs were provided to a number of teams within the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey collaboration to estimate the stellar masses for individual galaxies. A total of 11 teams participated, with different combinations of stellar mass measurement codes/methods, population synthesis models, star formation histories, extinction and age. For each simulated galaxy, the differences between the input stellar masses, Minput, and those estimated by each team, Mest, is defined as ${\rm{\Delta }}\mathrm{log}(M)\equiv \mathrm{log}({M}_{\mathrm{estimated}})-\mathrm{log}({M}_{\mathrm{input}})$, and used to identify the most fundamental parameters affecting stellar mass estimate in galaxies, with the following results. (1) No significant bias in Δ log(M) was found among different codes, with all having comparable scatter ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.136$ dex). The estimated stellar mass values are seriously affected by low photometric S/N, with the rms scatter increasing for galaxies with ${H}_{\mathrm{AB}}\gt 26$ mag; (2) A source of error contributing to the scatter in Δ log(M) is found to be due to photometric uncertainties (0.136 dex) and low resolution in age and extinction grids when generating the SED templates; (3) The median of stellar masses among different methods provides a stable measure of the mass associated with any given galaxy ($\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.142$ dex); (4) The Δ log(M) values are strongly correlated with deviations in age (defined as the difference between the estimated and expected values), with a weaker correlation with extinction; (5) The rms scatter in the estimated stellar masses due to free parameters (after fixing redshifts and initial mass function) are quantified and found to be $\sigma ({\rm{\Delta }}\mathrm{log}(M))=0.110$ dex; (6) Using the observed data, we studied the sensitivity of stellar masses to both the population synthesis codes and inclusion of nebular emission lines and found them to affect the stellar mass by 0.2 and 0.3 dex respectively.

KW - galaxies: distances and redshifts

KW - galaxies: high-redshift

KW - galaxies: photometry

KW - surveys

UR - http://dx.doi.org/10.1088/0004-637X/808/1/101

U2 - 10.1088/0004-637X/808/1/101

DO - 10.1088/0004-637X/808/1/101

M3 - Article

VL - 808

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

ER -