arXiv - PHYS - Astrophysics of Galaxies最新文献

{"title":"The circular velocity and halo mass functions of galaxies in the nearby Universe","authors":"Andrei Ristea, Luca Cortese, Brent Groves, A. Fraser-McKelvie, Danail Obreschkow, Karl Glazebrook","doi":"arxiv-2409.05081","DOIUrl":"https://doi.org/arxiv-2409.05081","url":null,"abstract":"The circular velocity function (CVF) of galaxies is a fundamental test of the\u0000$Lambda$ Cold Dark Matter (CDM) paradigm as it traces the variation of galaxy\u0000number densities with circular velocity ($v_{rm{circ}}$), a proxy for\u0000dynamical mass. Previous observational studies of the CVF have either been\u0000based on ion{H}{I}-rich galaxies, or encompassed low-number statistics and\u0000probed narrow ranges in $v_{rm{circ}}$. We present a benchmark computation of\u0000the CVF between $100-350 rm{km s^{-1}}$ using a sample of 3527\u0000nearby-Universe galaxies, representative for stellar masses between\u0000$10^{9.2}-10^{11.9} rm{M_{odot}}$. We find significantly larger number\u0000densities above 150 $rm{km s^{-1}}$ compared to results from ion{H}{I}\u0000surveys, pertaining to the morphological diversity of our sample. Leveraging\u0000the fact that circular velocities are tracing the gravitational potential of\u0000halos, we compute the halo mass function (HMF), covering $sim$1 dex of\u0000previously unprobed halo masses ($10^{11.7}-10^{12.7} rm{M_{odot}}$). The HMF\u0000for our sample, representative of the galaxy population with\u0000$M_{200}geqslant10^{11.35} rm{M_{odot}}$, shows that spiral morphologies\u0000contribute 67 per cent of the matter density in the nearby Universe, while\u0000early types account for the rest. We combine our HMF data with literature\u0000measurements based on ion{H}{I} kinematics and group/cluster velocity\u0000dispersions. We constrain the functional form of the HMF between\u0000$10^{10.5}-10^{15.5} rm{M_{odot}}$, finding a good agreement with\u0000$Lambda$CDM predictions. The halo mass range probed encompasses\u000072$substack{+5 -6}$ per cent ($Omega_{rm{M,10.5-15.5}} = 0.227 pm\u00000.018$) of the matter density in the nearby Universe; 31$substack{+5 -6}$\u0000per cent is accounted for by halos below $10^{12.7}rm{M_{odot}}$ occupied by\u0000a single galaxy.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abundant Molecular Gas in the Central Region of Lenticular Galaxy PGC 39535","authors":"Jiantong Cui, Qiusheng Gu, Shiying Lu, Zhengyi Chen, Can Xu, Zeyu Gao","doi":"arxiv-2409.05172","DOIUrl":"https://doi.org/arxiv-2409.05172","url":null,"abstract":"Lenticular galaxies (S0s) in the local universe are generally absent of\u0000recent star formation and lack molecular gas. In this paper, we investigate one\u0000massive ($M_*$$sim$5$times10^{10}$ M$_odot$) star-forming S0, PGC 39535,\u0000with the Northern Extended Millimeter Array (NOEMA). Using optical data from\u0000SDSS-IV MaNGA survey, we find star formation mainly concentrates in the central\u0000region of PGC 39535. The total star formation rate estimated using\u0000extinction-corrected H$alpha$ flux is 1.57 M$_odot$ yr$^{-1}$. Results of\u0000NOEMA observation suggest that the molecular gas mainly concentrates in the\u0000central regions as a gaseous bar and a ring-like structure, and shows similar\u0000kinematics as the stellar and ionized gas components. The total molecular gas\u0000mass estimated from CO(1-0) is (5.42$pm$1.52)$times$10$^{9}$ M$_{odot}$. We\u0000find PGC 39535 lies on the star-forming main sequence, but falls below\u0000Kennicutt-Schmidt relation of spiral galaxies, suggesting that the star\u0000formation efficiency may be suppressed by the massive bulge. The existence of a\u0000second Gaussian component in the CO spectrum of the central region indicates\u0000possible gas flows. Furthermore, our analyses suggest that PGC 39535 resides in\u0000the center of a massive group and the derived star formation history indicates\u0000it may experience a series of gas-rich mergers over the past 2$sim$7 Gyr.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental effects as a key factor in shaping star-forming S0 galaxies","authors":"Pei-Bin Chen, Junfeng Wang, Yan-Mei Chen, Xiao-Yu Xu, Tian-Wen Cao","doi":"arxiv-2409.05064","DOIUrl":"https://doi.org/arxiv-2409.05064","url":null,"abstract":"The origins of lenticular galaxies (S0s) can be classified into two main\u0000categories: ``minor mergers\" in low-density environments (LDEs) and ``faded\u0000spirals\" in high-density environments (HDEs). The transitional phase in the\u0000evolution of S0s, namely, star-forming lenticular galaxies (SFS0s), can serve\u0000as an important probe for analyzing the complex processes involved in the\u0000transformation between different galaxy types and the quenching of star\u0000formation (SF). We attempt to find the impact of different environments on the\u0000global properties and spatially resolved quantities of SFS0s. We selected 71\u0000SFS0s from the SDSS-IV MaNGA Survey, comprising 23 SFS0s in HDEs (SFS0s$_$HE)\u0000and 48 SFS0s in LDEs (SFS0s$_$LE). We examined the effects of the environment,\u0000by studying the global properties, concentration index, and radial profiles of\u0000the derived quantities. The varied environments of SFS0s do not lead to any\u0000significant difference in global properties (e.g., S$acute{rm e}$rsic index).\u0000By calculating $CI_{rm H_{alpha}/cont}$, we observe that different\u0000environments may cause varying concentrations of SF. Specifically, SFS0s$_$LE,\u0000affected by external gas mergers or inflow, exhibit a more centrally\u0000concentrated SF (i.e., larger $CI_{rm H_{alpha}/cont}$). This trend is\u0000further supported by $CI_{rm SFR, H_{alpha}}$, which only considers the gas\u0000disk of the galaxy. This observation is aligned with the observed shrinking of\u0000gas disks in galaxies affected by ram-pressure stripping in HDEs. Furthermore,\u0000their $Sigma_{rm SFR}$ or resolved sSFR are comparable. On average,\u0000SFS0s$_$LE display significantly higher values for both quantities. Finally,\u0000the observed D$_{rm n}4000$ and gas-phase metallicity gradient correspond well\u0000to their assumed origins. However, we did not find a significantly lower\u0000gas-phase metallicity in SFS0s$_$LE. Abridged","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"109 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two Channels of Metal-Rich Compact Stellar System Formation: Starbursts Under High Ram Pressure vs. Tidal Stripping","authors":"Yuan Bian, Min Du, Victor P. Debattista, Dylan Nelson, Mark A. Norris, Luis C. Ho, Shuai Lu, Renyue Cen, Shuo Ma, Chong Ge, Taotao Fang, Hui Li","doi":"arxiv-2409.05229","DOIUrl":"https://doi.org/arxiv-2409.05229","url":null,"abstract":"Most galaxies follow well-defined scaling relations of metallicity and\u0000stellar mass; however, some outliers at the low mass end of the observed galaxy\u0000population exhibit unusually high metallicity for their mass. Understanding how\u0000these objects get to be so metal-rich is vital for understanding the role of\u0000feedback in galaxy formation. Using the TNG50 simulation, we explore the\u0000origins of this phenomenon. We identify 227 metal-rich, Compact Stellar Systems\u0000(CSSs) that deviate significantly from this scaling relation. These CSSs are\u0000satellites located in the vicinity of massive host galaxies, with stellar\u0000masses ranging from $10^{8} M_{odot}$ to $10^{10} M_{odot}$ (including six\u0000systems that are close analogs of the M31-M32 system). Contrary to the\u0000previously assumed scenario that such objects are predominantly products of\u0000tidal stripping, our results suggest a more prevalent role for ram pressure in\u0000their formation. Indeed, 76% (173) of these CSSs are formed through a burst of\u0000star formation occurring around the time of the first pericentric passage,\u0000typically at redshifts $zlesssim1$, aided by strong ram pressure and tidal\u0000forces. The high ram pressure, resulting from the CSSs' rapid motion near the\u0000halo center, facilitates metal enrichment, producing high-metallicity CSSs by\u0000confining the metal-rich gas from bursty star formation, which leads to\u0000distinct stellar populations characterized by enhanced metallicity as well as\u0000high $alpha$-abundance. Only the remaining 24% (54) of metal-rich CSSs are\u0000generated through the tidal stripping of massive progenitors. Our results\u0000further indicate that M32 is more likely to have formed through intense star\u0000formation events rather than through gradual, tidal stripping, thereby\u0000providing crucial insights into the nature of low mass, compact galaxy\u0000formation.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Radiation and Supernovae Feedback on LyC Escape in Local Star-forming Galaxies","authors":"Cody A. Carr, Renyue Cen, Claudia Scarlata, Xinfeng Xu, Alaina Henry, Rui Marques-Chaves, Daniel Schaerer, Ricardo O. Amorín, M. S. Oey, Lena Komarova, Sophia Flury, Anne Jaskot, Alberto Saldana-Lopez, Zhiyuan Ji, Mason Huberty, Timothy Heckman, Göran Ostlin, Omkar Bait, Matthew James Hayes, Trinh Thuan, Danielle A. Berg, Mauro Giavalisco, Sanchayeeta Borthakur, John Chisholm, Harry C. Ferguson, Leo Michel-Dansac, Anne Verhamme, Gábor Worseck","doi":"arxiv-2409.05180","DOIUrl":"https://doi.org/arxiv-2409.05180","url":null,"abstract":"Feedback is widely recognized as an essential condition for Lyman continuum\u0000(LyC) escape in star-forming galaxies. However, the mechanisms by which\u0000galactic outflows clear neutral gas and dust remain unclear. In this paper, we\u0000model the Mg II 2796r{A}, 2804r{A} absorption + emission lines in 29 galaxies\u0000taken from the Low-z LyC Survey (LzLCS) to investigate the impact of (radiation\u0000+ mechanical) feedback on LyC escape. Using constraints on Mg$^+$ and\u0000photoionization models, we map the outflows' neutral hydrogen content and\u0000predict $f_{esc}^{LyC}$ with a multiphase wind model. We measure mass,\u0000momentum, and energy loading factors for the neutral winds, which carry up to\u000010% of the momentum and 1% of the energy in SFR-based deposition rates. We use\u0000SED template fitting to determine the relative ages of stellar populations,\u0000allowing us to identify radiation feedback dominant systems. We then examine\u0000feedback related properties (stellar age, loading factors, etc.) under\u0000conditions that optimize feedback efficiency, specifically high star formation\u0000rate surface density and compact UV half-light radii. Our findings indicate\u0000that the strongest leakers are radiation feedback dominant, lack Mg II\u0000outflows, but have extended broad components in higher ionization lines like [O\u0000III] 5007r{A}, as observed by Amor'in et al. (2024). In contrast, galaxies\u0000experiencing supernovae feedback typically exhibit weaker $f_{esc}^{LyC}$ and\u0000show evidence of outflows in both Mg II and higher ionization lines. We\u0000attribute these findings to rapid or \"catastrophic\" cooling in the\u0000radiation-dominant systems, which, given the low metallicities in our sample,\u0000are likely experiencing delayed supernovae.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Dark Energy Camera Magellanic Clouds Emission-Line Survey","authors":"Sean D. Points, Knox S. Long, William P. Blair, Rosa Williams, You-Hua Chu, P. Frank Winkler, Richard L. White, Armin Rest, Chuan-Jui Li, Francisco Valdes","doi":"arxiv-2409.04846","DOIUrl":"https://doi.org/arxiv-2409.04846","url":null,"abstract":"We have used the Dark Energy Camera (DECam) on the CTIO Blanco 4-m telescope\u0000to perform a new emission-line survey of the Large Magellanic Cloud (LMC) using\u0000narrow-band H-alpha and [SII] filters in addition to a continuum band for use\u0000in creating pure emission-line images. We refer to this new survey as DeMCELS,\u0000to distinguish it from the earlier Magellanic Cloud Emission Line Survey\u0000(MCELS) that has been in service for nearly 25 years. DeMCELS covers $sim 54$\u0000degrees$^{2}$, encompassing most of the bright optical disk of the LMC. With\u0000DECam's pixel size of only 0.27\", our DeMCELS survey provides a seeing-limited\u0000improvement of 3-5 times over MCELS and is comparable in depth, with surface\u0000brightness limits of 3.3E-17 erg cm$^{-2}$ s$^{-1}$ arcsec$^{-2}$ in H-alpha\u0000and 2.9E-17 erg cm$^{-2}$ s$^{-1}$ arcsec$^{-2}$ in H-alpha and [SII],\u0000respectively. DeMCELS provides detailed morphological information on nebulae of\u0000all scales, from the largest supershells to individual [HII] regions and\u0000supernova remnants, to bubbles of emission surrounding individual stars, and\u0000even to faint structures in the diffuse ionized gas of the LMC. Many complex\u0000regions of emission show significant variations in the ratio of [SII] to\u0000H-alpha, a sign of the mixture of shocks from stellar winds and/or supernovae\u0000with photoionization by embedded hot, young stars. We present the details of\u0000the observing strategy and data processing for this survey, and show selected\u0000results in comparison with previous data. A companion project for the Small\u0000Magellanic Cloud is in progress and will be reported separately. We are making\u0000these new data available to the community at large via the NOIRLab's Data Lab\u0000site.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A pair of possible supernovae Refsdal in the Pantheon+ sample","authors":"Yves-Henri Sanejouand","doi":"arxiv-2409.05913","DOIUrl":"https://doi.org/arxiv-2409.05913","url":null,"abstract":"On December 1980, supernova 1980N was discovered in NGC 1316, a galaxy of the\u0000Fornax cluster. Three months later, supernova 1981D was observed in the same\u0000galaxy. The light curves of these two supernovae Ia were found to be virtually\u0000identical, suggesting that they are images of the same event, the delay between\u0000them being due to strong gravitational lensing. If so, as anticipated by Sjur\u0000Refsdal, the distance to the lens can be determined accurately, namely, 90\u0000$pm$ 1 kpc, meaning that it belongs to the outer halo of the Milky Way. Interestingly, there is another pair of possible images in the Pantheon+\u0000sample, namely, supernovae 2013aa and 2017cbv, the distance to the lens being\u0000702 $pm$ 1 kpc, that is, nearly the same as the distance to the Andromeda\u0000galaxy. In both cases, given the relatively large angle of deviation of the supernova\u0000light by the lens, namely, 271\" and 325\", respectively, the lens has to be a\u0000compact object, with a mass to radius ratio over 150 M$_odot$ R$_odot^{-1}$.\u0000It is likely to be an ultra massive white dwarf.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Intrinsic Distribution of Lyman-$α$ Halos","authors":"John Pharo, Lutz Wisotzki, Tanya Urrutia, Roland Bacon, Ismael Pessa, Ramona Augustin, Ilias Goovaerts, Daria Kozlova, Haruka Kusakabe, Héctor Salas, Daniil Smirnov, Tran Thi Thai, Eloïse Vitte","doi":"arxiv-2409.04537","DOIUrl":"https://doi.org/arxiv-2409.04537","url":null,"abstract":"The emission and escape of Lyman-$alpha$ photons from star-forming galaxies\u0000is determined through complex interactions between the emitted photons and a\u0000galaxy's interstellar and circumgalactic gas, causing Lyman-$alpha$ emitters\u0000(LAEs) to commonly appear not as point sources but in spatially extended halos\u0000with complex spectral profiles. We develop a 3D spatial-spectral model of\u0000Lyman-$alpha$ halos (LAHs) to replicate LAH observations in integral field\u0000spectroscopic studies, such as those made with VLT/MUSE. The profile of this\u0000model is a function of 6 key halo properties: the halo- and compact-source\u0000exponential scale lengths ($r_{sH}$ and $r_{sC}$), the halo flux fraction\u0000($f_H$), the compact component ellipticity ($q$), the spectral line width\u0000($sigma$), and the spectral line skewness parameter ($gamma$). Placing a\u0000series of model LAHs into datacubes reflecting observing conditions in the MUSE\u0000UDF-Mosaic survey, we test their detection recoverability and determine that\u0000$sigma$, $r_{sH}$, and $f_H$ are expected to have the most significant effect\u0000on the detectability of the overall LAH at a given central wavelength and\u0000intrinsic line luminosity. We develop a general selection function model\u0000spanning a grid of these halo parameters, and with a sample of 145 UDF-Mosaic\u0000LAHs with measured halo properties, we derive completeness-corrected, intrinsic\u0000distributions of the values of $sigma$, $r_{sH}$, and $f_H$ for $3<z<5$ LAHs.\u0000We present best-fit functional forms of the distributions, and a $sigma$\u0000distribution corrected for instrumental line-spread function (LSF) broadening,\u0000and thereby show the physical line spread distribution of the intrinsic\u0000population. Finally, we discuss implications of these distributions for\u0000Ly$alpha$ emission through the circumgalactic medium, finding that\u0000observations undercount LAHs with extended halo scale lengths compared to the\u0000intrinsic population.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The External Heating of Dust in a Homogeneous Spherical Shell","authors":"Eli Dwek, Richard G. Arendt","doi":"arxiv-2409.04391","DOIUrl":"https://doi.org/arxiv-2409.04391","url":null,"abstract":"We present a procedure for calculating the heating of, and the infrared\u0000emission from, dust in a homogeneous spherical shell surrounded by a\u0000spherically symmetric source of radiation. The results are applicable to newly\u0000formed dust either in supernova ejecta or in the circumstellar medium that has\u0000been swept up by the expanding shock wave. They can also be applied to the\u0000heating and IR emission from dust in clumps or clouds embedded in a homogeneous\u0000radiation field.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Arizona Molecular ISM Survey with the SMT: Variations in the CO(2-1)/CO(1-0) Line Ratio Across the Galaxy Population","authors":"Ryan P. Keenan, Daniel P. Marrone, Garrett K. Keating","doi":"arxiv-2409.03963","DOIUrl":"https://doi.org/arxiv-2409.03963","url":null,"abstract":"The J=1$rightarrow$0 spectral line of carbon monoxide (CO(1-0)) is the\u0000canonical tracer of molecular gas. However, CO(2-1) is frequently used in its\u0000place, following the assumption that the higher energy line can be used to\u0000infer the CO(1-0) luminosity and molecular gas mass. The use of CO(2-1) depends\u0000on a knowledge of the ratio between CO(2-1) and CO(1-0) luminosities, r21. Here\u0000we present galaxy-integrated r21 measurements for 122 galaxies spanning stellar\u0000masses from 10$^9$ to 10$^{11.5}$ M$_odot$ and star formation rates (SFRs)\u0000from 0.08 to 35 M$_odot$/yr. We find strong trends between r21 and SFR, SFR\u0000surface density, star formation efficiency, and distance from the star\u0000formation main sequence (SFMS). We show that the assumption of a constant r21\u0000can introduce biases into the molecular gas trends in galaxy population studies\u0000and demonstrate how this affects the recovery of important galaxy scaling\u0000relations, including the Kennicutt-Schmidt law and the relation between SFMS\u0000offset and star formation efficiency. We provide a prescription which accounts\u0000for variations in r21 as a function of SFR and can be used to convert between\u0000CO(2-1) and CO(1-0) when only one line is available. Our prescription matches\u0000variations in r21 for both AMISS and literature samples and can be used to\u0000derive more accurate gas masses from CO(2-1) observations.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"229 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}