MAGPHYS+photo-z: Constraining the Physical Properties of Galaxies with Unknown Redshifts

Collaboration Cosmos Collaboration, A. J. Battisti, E. Da Cunha, K. Grasha, M. Salvato, E. Daddi, L. Davies, Shuowen Jin, Daizhong Liu, E. Schinnerer, M. Vaccari

Research output: Contribution to journalArticle

Abstract

We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color versus redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision (), high accuracy (i.e., minimal offset biases; median(Δz/(1 + z spec)) ≲ 0.02), and low catastrophic failure rates (η ≃ 4%) over all redshifts. Interestingly, we find that a weak 2175 Å absorption feature in the attenuation curve models is required to remove a subtle systematic z phot offset () that occurs when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric data sets. Finally, we emphasize that MAGPHYS+photo-z is not intended to replace existing photo-z codes, but rather offers flexibility to robustly interpret physical properties when spectroscopic redshifts are unavailable. The MAGPHYS+photo-z code is publicly available online.

Original languageEnglish
Article number61
Number of pages21
JournalAstrophysical Journal
Volume882
Issue number1
DOIs
Publication statusPublished - 4 Sep 2019

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physical property
physical properties
galaxies
attenuation
wavelength
star formation rate
stellar mass
wavelengths
modeling
code
flexibility
estimating
dust
radio
color
curves
rate

Cite this

Cosmos Collaboration, C., Battisti, A. J., Da Cunha, E., Grasha, K., Salvato, M., Daddi, E., ... Vaccari, M. (2019). MAGPHYS+photo-z: Constraining the Physical Properties of Galaxies with Unknown Redshifts. Astrophysical Journal, 882(1), [61]. https://doi.org/10.3847/1538-4357/ab345d
Cosmos Collaboration, Collaboration ; Battisti, A. J. ; Da Cunha, E. ; Grasha, K. ; Salvato, M. ; Daddi, E. ; Davies, L. ; Jin, Shuowen ; Liu, Daizhong ; Schinnerer, E. ; Vaccari, M. / MAGPHYS+photo-z : Constraining the Physical Properties of Galaxies with Unknown Redshifts. In: Astrophysical Journal. 2019 ; Vol. 882, No. 1.
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abstract = "We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color versus redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision (), high accuracy (i.e., minimal offset biases; median(Δz/(1 + z spec)) ≲ 0.02), and low catastrophic failure rates (η ≃ 4{\%}) over all redshifts. Interestingly, we find that a weak 2175 {\AA} absorption feature in the attenuation curve models is required to remove a subtle systematic z phot offset () that occurs when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric data sets. Finally, we emphasize that MAGPHYS+photo-z is not intended to replace existing photo-z codes, but rather offers flexibility to robustly interpret physical properties when spectroscopic redshifts are unavailable. The MAGPHYS+photo-z code is publicly available online.",
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Cosmos Collaboration, C, Battisti, AJ, Da Cunha, E, Grasha, K, Salvato, M, Daddi, E, Davies, L, Jin, S, Liu, D, Schinnerer, E & Vaccari, M 2019, 'MAGPHYS+photo-z: Constraining the Physical Properties of Galaxies with Unknown Redshifts' Astrophysical Journal, vol. 882, no. 1, 61. https://doi.org/10.3847/1538-4357/ab345d

MAGPHYS+photo-z : Constraining the Physical Properties of Galaxies with Unknown Redshifts. / Cosmos Collaboration, Collaboration; Battisti, A. J.; Da Cunha, E.; Grasha, K.; Salvato, M.; Daddi, E.; Davies, L.; Jin, Shuowen; Liu, Daizhong; Schinnerer, E.; Vaccari, M.

In: Astrophysical Journal, Vol. 882, No. 1, 61, 04.09.2019.

Research output: Contribution to journalArticle

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T2 - Constraining the Physical Properties of Galaxies with Unknown Redshifts

AU - Cosmos Collaboration, Collaboration

AU - Battisti, A. J.

AU - Da Cunha, E.

AU - Grasha, K.

AU - Salvato, M.

AU - Daddi, E.

AU - Davies, L.

AU - Jin, Shuowen

AU - Liu, Daizhong

AU - Schinnerer, E.

AU - Vaccari, M.

PY - 2019/9/4

Y1 - 2019/9/4

N2 - We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color versus redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision (), high accuracy (i.e., minimal offset biases; median(Δz/(1 + z spec)) ≲ 0.02), and low catastrophic failure rates (η ≃ 4%) over all redshifts. Interestingly, we find that a weak 2175 Å absorption feature in the attenuation curve models is required to remove a subtle systematic z phot offset () that occurs when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric data sets. Finally, we emphasize that MAGPHYS+photo-z is not intended to replace existing photo-z codes, but rather offers flexibility to robustly interpret physical properties when spectroscopic redshifts are unavailable. The MAGPHYS+photo-z code is publicly available online.

AB - We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color versus redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision (), high accuracy (i.e., minimal offset biases; median(Δz/(1 + z spec)) ≲ 0.02), and low catastrophic failure rates (η ≃ 4%) over all redshifts. Interestingly, we find that a weak 2175 Å absorption feature in the attenuation curve models is required to remove a subtle systematic z phot offset () that occurs when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric data sets. Finally, we emphasize that MAGPHYS+photo-z is not intended to replace existing photo-z codes, but rather offers flexibility to robustly interpret physical properties when spectroscopic redshifts are unavailable. The MAGPHYS+photo-z code is publicly available online.

KW - galaxies: evolution

KW - galaxies: fundamental parameters

KW - galaxies: ISM

KW - galaxies: photometry

KW - infrared: galaxies

KW - submillimeter: galaxies

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Cosmos Collaboration C, Battisti AJ, Da Cunha E, Grasha K, Salvato M, Daddi E et al. MAGPHYS+photo-z: Constraining the Physical Properties of Galaxies with Unknown Redshifts. Astrophysical Journal. 2019 Sep 4;882(1). 61. https://doi.org/10.3847/1538-4357/ab345d