Measuring Scaling Relations: Fitting Technique Matters

Scaling relationships, both integrated and spatially resolved, arise owing to the physical processes that govern galaxy evolution and are frequently measured in both observed and simulated data. However, the accuracy and comparability of these measurements are hindered by various differences between...

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Main Authors: Bryanne McDonough, Olivia Curtis, Tereasa G. Brainerd
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
Subjects:
Online Access:https://doi.org/10.3847/2041-8213/ade13c
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author Bryanne McDonough
Olivia Curtis
Tereasa G. Brainerd
author_facet Bryanne McDonough
Olivia Curtis
Tereasa G. Brainerd
author_sort Bryanne McDonough
collection DOAJ
description Scaling relationships, both integrated and spatially resolved, arise owing to the physical processes that govern galaxy evolution and are frequently measured in both observed and simulated data. However, the accuracy and comparability of these measurements are hindered by various differences between studies such as spatial resolution, sample selection criteria, and fitting technique. In this Letter, we compare variations of standard least-squares techniques to the ridge line method for identifying spatially resolved scaling relations (Σ _* −Σ _SFR , Σ _* −Σ _gas , and Σ _gas −Σ _SFR ) for TNG100 galaxies. We find that using the ridge line technique to fit these scaling relations with a double linear function (in logarithmic space) results in significantly better fits than fitting with ordinary least squares. We further illustrate the utility of the ridge line technique with an investigation into the dependence of resolved star formation main-sequence (rSFMS) measurements on spatial resolution and smoothing scale. Specifically, we find that the slope of the rSFMS at low Σ _* is independent (within 2 σ ) of spatial resolution and smoothing scale. Finally, we discuss the need for a consistent reanalysis of resolved scaling relations in the literature and physically motivate adoption of the ridge line technique over other fitting methods.
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spelling doaj-art-68e3f41ecbbf478482a3706aeec094ee2025-08-20T03:22:16ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019862L3210.3847/2041-8213/ade13cMeasuring Scaling Relations: Fitting Technique MattersBryanne McDonough0https://orcid.org/0000-0001-6928-4345Olivia Curtis1https://orcid.org/0000-0002-0212-4563Tereasa G. Brainerd2https://orcid.org/0000-0001-7917-7623Department of Physics, Northeastern University , 360 Huntington Ave., Boston, MA 02115, USA ; br.mcdonough@northeastern.edu; Institute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215, USAInstitute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215, USA; Department of Astronomy & Astrophysics, The Pennsylvania State University , 251 Pollock Road, University Park, PA 16802, USAInstitute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215, USAScaling relationships, both integrated and spatially resolved, arise owing to the physical processes that govern galaxy evolution and are frequently measured in both observed and simulated data. However, the accuracy and comparability of these measurements are hindered by various differences between studies such as spatial resolution, sample selection criteria, and fitting technique. In this Letter, we compare variations of standard least-squares techniques to the ridge line method for identifying spatially resolved scaling relations (Σ _* −Σ _SFR , Σ _* −Σ _gas , and Σ _gas −Σ _SFR ) for TNG100 galaxies. We find that using the ridge line technique to fit these scaling relations with a double linear function (in logarithmic space) results in significantly better fits than fitting with ordinary least squares. We further illustrate the utility of the ridge line technique with an investigation into the dependence of resolved star formation main-sequence (rSFMS) measurements on spatial resolution and smoothing scale. Specifically, we find that the slope of the rSFMS at low Σ _* is independent (within 2 σ ) of spatial resolution and smoothing scale. Finally, we discuss the need for a consistent reanalysis of resolved scaling relations in the literature and physically motivate adoption of the ridge line technique over other fitting methods.https://doi.org/10.3847/2041-8213/ade13cStar formationAstronomical simulationsGalaxy propertiesGalaxy evolutionScaling relations
spellingShingle Bryanne McDonough
Olivia Curtis
Tereasa G. Brainerd
Measuring Scaling Relations: Fitting Technique Matters
The Astrophysical Journal Letters
Star formation
Astronomical simulations
Galaxy properties
Galaxy evolution
Scaling relations
title Measuring Scaling Relations: Fitting Technique Matters
title_full Measuring Scaling Relations: Fitting Technique Matters
title_fullStr Measuring Scaling Relations: Fitting Technique Matters
title_full_unstemmed Measuring Scaling Relations: Fitting Technique Matters
title_short Measuring Scaling Relations: Fitting Technique Matters
title_sort measuring scaling relations fitting technique matters
topic Star formation
Astronomical simulations
Galaxy properties
Galaxy evolution
Scaling relations
url https://doi.org/10.3847/2041-8213/ade13c
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AT oliviacurtis measuringscalingrelationsfittingtechniquematters
AT tereasagbrainerd measuringscalingrelationsfittingtechniquematters