arXiv - PHYS - Astrophysics of Galaxies最新文献

{"title":"A survey of extremely metal-poor gas at cosmic noon: evidence of elevated [O/Fe]","authors":"Louise Welsh, Ryan Cooke, Michele Fumagalli, Max Pettini, Gwen C. Rudie","doi":"arxiv-2409.07525","DOIUrl":"https://doi.org/arxiv-2409.07525","url":null,"abstract":"We aim to study the high-precision chemical abundances of metal-poor gas\u0000clouds at cosmic noon (2<z<4) and investigate the associated enrichment\u0000histories. We analyse the abundances of four newly discovered metal-poor gas\u0000clouds utilising observations conducted with Keck/HIRES and VLT/UVES. These\u0000systems are classified as very metal-poor (VMP), with [Fe/H]<-2.57, and one\u0000system qualifies as an extremely metal-poor (EMP) Damped Lyman-alpha (DLA)\u0000system with [Fe/H]=-3.13+/-0.06. In combination with new high-resolution data\u0000of two previously known EMP DLAs and 2 systems reported in the literature, we\u0000conduct a comprehensive analysis of eight of the most metal-poor gas clouds\u0000currently known. We focus on high-precision abundance measurements using the\u0000elements: C, N, O, Al, Si, and Fe. Our findings indicate increasing evidence of\u0000elevated [O/Fe] abundances when [Fe/H]<-3. EMP DLAs are well-modelled with a\u0000mean value of [O/Fe]=+0.50 +/- 0.04 and an intrinsic scatter of\u0000$sigma_{int,[O/Fe]}=0.13^{+0.06}_{-0.04}$. While VMP DLAs are well-modelled\u0000with [O/Fe]=+0.40 +/- 0.02 and $sigma_{int,[O/Fe]}$=0.06 +/- 0.02. We further\u0000find tentative evidence of a redshift evolution of [C/O] across these most\u0000metal-poor DLAs with lower redshift systems showing elevated [C/O] ratios.\u0000Using the measured abundances, combined with a stochastic chemical enrichment\u0000model, we investigate the properties of the stellar population responsible for\u0000enriching EMP gas at cosmic noon. We find that the chemistry of these systems\u0000is best explained via the enrichment of just two massive progenitors,\u0000N_*=2+/-1, that ended their lives as core collapse SNe with a typical explosion\u0000energy E_exp=(1.6 +/- 0.6)x10$^{51}$ erg. These progenitors formed obeying a\u0000Salpeter-like power-law IMF, where all stars of mass greater than\u0000M_max=32$^{+10}_{-4}$ M_sun collapse directly to black holes and do not\u0000contribute to the metal enrichment.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"396 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195367","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":"CHEMOUT: CHEMical complexity in star-forming regions of the OUTer Galaxy. IV. ALMA observations of organic species at Galactocentric radius ~23 kpc","authors":"F. FontaniINAF - Osservatorio Astrofisico di Arcetri, Florence, ItalyMax-Planck-Institut für extraterrestrische Physik, Garching bei München, GermanyLERMA, Observatoire de Paris, Meudon, France, G. VermariënLeiden Observatory, Leiden, The Netherlands, S. VitiLeiden Observatory, Leiden, The Netherlands, D. GigliINAF - Osservatorio Astrofisico di Arcetri, Florence, ItalyDipartimento di Fisica e Astronomia, Sesto Fiorentino, L. ColziCentro de Astrobiología, M. T. BeltránINAF - Osservatorio Astrofisico di Arcetri, Florence, Italy, P. CaselliMax-Planck-Institut für extraterrestrische Physik, Garching bei München, Germany, V. M. RivillaCentro de Astrobiología, ÁInstitut de Ciències de l'EspaiInstitut d'Estudis Espacials de Catalunya, Sánchez-MongeInstitut de Ciències de l'EspaiInstitut d'Estudis Espacials de Catalunya","doi":"arxiv-2409.07243","DOIUrl":"https://doi.org/arxiv-2409.07243","url":null,"abstract":"Single-dish observations suggest that the abundances of organic species in\u0000star-forming regions of the outer Galaxy, characterised by sub-Solar\u0000metallicities, are comparable to those found in the local Galaxy. To understand\u0000this counter-intuitive result, and avoid misleading interpretation due to beam\u0000dilution effects at such large distances, spatially resolved molecular emission\u0000maps are needed to link correctly measured abundances and local physical\u0000properties. We observed several organic molecules with the Atacama Large\u0000Millimeter Array towards WB89-671, the source with the largest Galactocentric\u0000distance (23.4~kpc) of the project \"CHEMical complexity in star-forming regions\u0000of the OUTer Galaxy\" (CHEMOUT), at a resolution of 15000~au. We compared the\u0000observed molecular abundances with chemical model predictions. We detected\u0000emission of c-C3H2, C4H, CH3OH, H2CO, HCO, H13CO+, HCS+, CS, HN13C, and SO. The\u0000emission morphology is complex, extended, and different in each tracer. The\u0000most intense emission in H13CO+, H2CO and c-C3H2 arises from two millimeter\u0000continuum, infrared-bright cores. The most intense CH3OH and SO emission arises\u0000predominantly from the part of the filament with no continuum sources. The\u0000narrow linewidths across the filament indicate quiescent gas, despite the two\u0000embedded protostars. Derived molecular column densities are comparable with\u0000those in local star-forming regions, and suggest anti-correlation between\u0000hydrocarbons, ions, HCO, and H2CO on one side, and CH3OH and SO on the other.\u0000Static chemical models that best match the observed column densities favour low\u0000energetic conditions, expected at large Galactocentric radii, but carbon\u0000elemental abundances 3 times higher than that derived extrapolating the [C/H]\u0000Galactocentric gradient at 23~kpc. This would indicate a flatter [C/H] trend at\u0000large Galactocentric radii, in line with a flat abundance of organics.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195374","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":"Core Revelations: the Star Formation and AGN Connection at the Heart of NGC 7469","authors":"Léa M. Feuillet, Steve Kraemer, Marcio B. Meléndez, Travis C. Fischer, Henrique R. Schmitt, James N. Reeves, Anna Trindade Falcão","doi":"arxiv-2409.07665","DOIUrl":"https://doi.org/arxiv-2409.07665","url":null,"abstract":"We investigate the star formation-AGN connection in the Seyfert 1 NGC 7469\u0000using James Webb Space Telescope (JWST) mid-infrared spectroscopic integral\u0000field unit (IFU) data. We use the IFU data to generate maps of different\u0000emission lines present in the spectrum, such as the star-formation (SF) tracer\u0000[Ne II] 12.81{mu}m, or the AGN tracer [Ne V] 14.32{mu}m. We can separate the\u0000AGN- and SF-dominated regions using spatially resolved mid-IR diagnostic\u0000diagrams, and further investigate the ionization sources powering each region\u0000by constructing photoionization models. We find that the previously detected\u0000eastern wind populates an intermediary region of the diagrams, between our\u0000star-forming and AGN quadrants. This wind also coincides with a reduction in\u0000the [Ne II] emission in the ring, which suggests that the ionization cone\u0000intersects the ring in this direction. In spite of this evidence of negative\u0000AGN feedback, given the narrow opening angle of the ionization cone and its\u0000orientation, this would not be a case of efficient feedback.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195364","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":"One Stream or Two -- Exploring Andromeda's North West Stream","authors":"Janet Preston, Denis Erkal, Michelle L. M. Collins, R. Michael Rich, Rodrigo Ibata, Maxime Delorme","doi":"arxiv-2409.07419","DOIUrl":"https://doi.org/arxiv-2409.07419","url":null,"abstract":"We present results of our dynamical stream modelling for the North West\u0000Stream in the outer halo of the Andromeda galaxy (M31). Comprising two main\u0000segments, the North West Stream was thought to be a single structured arching\u0000around M31. However, recent evidence suggests that it is two separate,\u0000unrelated, streams. To test this hypothesis we use observational data from 6\u0000fields associated with the upper segment of the North West Stream together with\u00008 fields and 5 globular clusters associated with the lower segment to constrain\u0000model orbits. We fit both segments of the stream using a fixed potential model\u0000for M31 and an orbit integrator to compare orbits with the observed streams. We\u0000measure the central tracks and predict proper motions for for the upper segment\u0000(lower segment) finding ${mu^*_{alpha}}$ = 0.078$^{+0.015}_{-0.012}$\u0000(0.085$^{+0.001}_{-0.002}$) mas/yr and ${mu_{delta}}$ =\u0000$-$0.05$^{+0.008}_{-0.009}$ ($-$0.095$^{+0.003}_{-0.005}$) mas/yr. Our results\u0000support the hypothesis that the dwarf spheroidal galaxy Andromeda XXVII is the\u0000progenitor of the upper segment of the North West Stream and that the upper and\u0000lower segments do not comprise a single structure. We propose that the upper\u0000segment, which appears to be on an infall trajectory with M31, be renamed the\u0000\"Andromeda XXVII Stream\" and the lower segment, also apparently infalling\u0000towards M31, retain the name \"North West Stream\".","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195370","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":"Properties of the Lower Segment of M31's North West Stream","authors":"Janet Preston, Denis Erkal, Michelle L. M. Collins, Rodrigo Ibata, R. Michael Rich","doi":"arxiv-2409.07410","DOIUrl":"https://doi.org/arxiv-2409.07410","url":null,"abstract":"We present a kinematic and spectroscopic analysis of 40 red giant branch\u0000stars, in 9 fields, exquisitely delineating the lower segment of the North West\u0000Stream (NW-K2), which extends for $sim$80 kpc from the centre of the Andromeda\u0000galaxy. We measure the stream's systemic velocity as -439.3$^{+4.1}_{-3.8}$\u0000km/s with a velocity dispersion = 16.4$^{+5.6}_{-3.8}$ km/s that is in keeping\u0000with its progenitor being a dwarf galaxy. We find no detectable velocity\u0000gradient along the stream. We determine $-$1.3$pm$0.1 $le$ <[Fe/H]$_{rm\u0000spec}$> $le$ $-$1.2$pm$0.8 but find no metallicity gradient along the stream.\u0000We are able to plausibly associate NW-K2 with the globular clusters PandAS-04,\u0000PandAS-09, PAndAS-10, PAndAS-11, PandAS-12 but not with PandAS-13 or PandAS-15\u0000which we find to be superimposed on the stream but not kinematically associated\u0000with it.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"77 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195371","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":"Helical randomization of magnetized Galactic plasmas: from magnetorotational disc dynamo to the Faraday rotation sky","authors":"A. Bershadskii","doi":"arxiv-2409.07399","DOIUrl":"https://doi.org/arxiv-2409.07399","url":null,"abstract":"It is shown, using results of numerical simulations and galactic observations\u0000that the transition from deterministic chaos to hard turbulence in the Galactic\u0000magnetized plasmas (global and those generated in the internal accretion disk\u0000in the high-energy surrounding of a supermassive black hole at the Galactic\u0000center) happens through a randomization process. The notion of distributed\u0000chaos has been used to describe the randomization process. The randomization\u0000can be quantified with the main parameter of the distributed chaos which in\u0000turn can be related to magnetic helicity or its dissipation rate. The magnetic\u0000fields can impose their level of randomization on the electron density. Results\u0000of the numerical simulations of the Galactic dynamos: the inner disk's ones\u0000(based on the magnetorotational instability) and global ones, are in good\u0000agreement with this approach, as well as with the results obtained using\u0000observations of the Faraday rotation sky.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195375","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 assembly of the most rotationally supported disc galaxies in the TNG100 simulations","authors":"Silvio Rodriguez, Valeria A. Cristiani, Laura V. Sales, Mario G. Abadi","doi":"arxiv-2409.07553","DOIUrl":"https://doi.org/arxiv-2409.07553","url":null,"abstract":"Disc dominated galaxies can be difficult to accommodate in a hierarchical\u0000formation scenario like $Lambda$CDM, where mergers are an important growth\u0000mechanism. However, observational evidence indicates that these galaxies are\u0000common. We seek to characterise the conditions that lead to the formation of\u0000disc dominated galaxies within $Lambda$CDM. We use dynamical decomposition in\u0000all galaxies with stellar mass $M_*=[10^{10} rm - 10^{11}]; rm M_odot$\u0000within the simulation Illustris TNG100. We select a sample of 43 mostly-disc\u0000galaxies having less than $sim 10%$ of their mass into a bulge component. For\u0000comparison, we also study two additional stellar-mass matched samples: 43\u0000intermediate galaxies having $sim 30%$ of their mass in the bulge and 43 with\u0000purely spheroidal-like morphology. We find that the selection based on stellar\u0000dynamics is able to reproduce the expected stellar population trends of\u0000different morphologies, with higher star-formation rates and younger stars in\u0000disc-dominated galaxies. Halo spin seems to play no role in the morphology of\u0000the galaxies. At fixed $M_*$, our mostly-disc and intermediate samples form in\u0000dark matter haloes that are $2$-$10$ times less massive than the spheroidal\u0000sample, highlighting a higher efficiency in disc galaxies to retain and\u0000condensate their baryons. On average, mergers are less prevalent in the build\u0000up of discs than in spheroidal galaxies, but there is a large scatter,\u0000including the existence of mostly-disc galaxies with $15%$-$30%$ of their\u0000stars from accreted origin. Discs start forming early on, settling their low\u0000vertical velocity dispersion as early as $9$-$10$ Gyr ago, although the\u0000dominance of the disc over the spheroid gets established more recently ($3$-$4$\u0000Gyr ago). The most rotationally supported discs form in haloes with the lowest\u0000mass in the sample and best aligned distribution of angular momentum in the\u0000gas.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195365","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":"Clues of the restarting active galactic nucleus activity of Mrk 1498 from GTC/MEGARA integral field spectroscopy data","authors":"S. Cazzoli, L. Hernández-García, I. Márquez, J. Masegosa, G. Bruni, F. Panessa, L. Bassani","doi":"arxiv-2409.07534","DOIUrl":"https://doi.org/arxiv-2409.07534","url":null,"abstract":"Some giant radio galaxies selected at X-rays with an AGN show signs of a\u0000restarted nuclear activity. One object in this peculiar class is Mrk1498, a\u0000giant low-frequency double radio source that shows extended emission in [OIII].\u0000This emission is likely related to the history of the nuclear activity of the\u0000galaxy. We investigate whether this bubble-like emission might trace an outflow\u0000from either present or past AGN activity. Using MEGARA/GTC, medium-resolution\u0000spectroscopy (R 10000) data, we obtained the kinematics and fluxes of the\u0000ionised gas from modelling the [OIII] and Hbeta features.with three kinematic\u0000components. All the components show an overall blue to red velocity pattern,\u0000with similar peak-to-peak velocities but a different velocity dispersion. At a\u0000galactocentric distance of 2.3 kpc, we found a blob with a velocity up to\u0000100km/s, and a high velocity dispersion (170km/s) that is spatially coincident\u0000with the direction of the radio jet. The observed [OIII]/Hbeta line ratio\u0000indicates possible ionisation from AGN or shocks nearly everywhere. The clumpy\u0000structure visibile in HST images at kpc scales show the lowest values of\u0000log[OIII]/Hbeta , which is likely not related to the photoionisation by the\u0000AGN. Taking optical and radio activity into account, we propose a scenario of\u0000two different ionised gas features over the radio AGN lifecycle of Mrk 1498.\u0000The radio emission suggests at least two main radio activity episodes: an old\u0000episode at Mpc scales (formed during a time span of 100Myr), and a new episode\u0000from the core (>2000yr ago). At optical wavelengths, we observe clumps and a\u0000blob that are likely associated with fossil outflow. The latter is likely\u0000powered by past episodes of the flickering AGN activity that may have occurred\u0000between the two main radio phases.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195363","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 PIPER Survey. II. The Globular Cluster Systems of Low Surface Brightness Galaxies in the Perseus Cluster","authors":"Steven R. Janssens, Duncan A. Forbes, Aaron J. Romanowsky, Jonah Gannon, Joel Pfeffer, Warrick J. Couch, Jean P. Brodie, William E. Harris, Patrick R. Durrell, Kenji Bekki","doi":"arxiv-2409.07518","DOIUrl":"https://doi.org/arxiv-2409.07518","url":null,"abstract":"We present Hubble Space Telescope ACS/WFC and WFC3/UVIS imaging for a sample\u0000of 50 low surface brightness (LSB) galaxies in the $sim$10$^{15}$ M$_{odot}$\u0000Perseus cluster, which were originally identified in ground-based imaging. We\u0000measure the structural properties of these galaxies and estimate the total\u0000number of globular clusters (GCs) they host. Around half of our sample galaxies\u0000meet the strict definition of an ultra-diffuse galaxy (UDG), while the others\u0000are UDG-like but are either somewhat more compact or slightly brighter. A small\u0000number of galaxies reveal systems with many tens of GCs, rivalling some of the\u0000richest GC systems known around UDGs in the Coma cluster. We find the sizes of\u0000rich GC systems, in terms of their half-number radii, extending to $sim$1.2\u0000times the half-light radii of their host galaxy on average. The mean colours of\u0000the GC systems are the same, within the uncertainties, as those of their host\u0000galaxy stars. This suggests that GCs and galaxy field stars may have formed at\u0000the same epoch from the same enriched gas. It may also indicate a significant\u0000contribution from disrupted GCs to the stellar component of the host galaxy as\u0000might be expected in the 'failed galaxy' formation scenario for UDGs.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195368","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 Impact of Shear on Disk Galaxy Star Formation Rates","authors":"Xena L. Fortune-Bashee, Jiayi Sun, Jonathan C. Tan","doi":"arxiv-2409.07622","DOIUrl":"https://doi.org/arxiv-2409.07622","url":null,"abstract":"Determining the physical processes that control galactic-scale star formation\u0000rates is essential for an improved understanding of galaxy evolution. The role\u0000of orbital shear is currently unclear, with some models expecting reduced star\u0000formation rates (SFRs) and efficiencies (SFEs) with increasing shear, e.g., if\u0000shear stabilizes gas against gravitational collapse, while others predicting\u0000enhanced rates, e.g., if shear-driven collisions between giant molecular clouds\u0000(GMCs) trigger star formation. Expanding on the analysis of 16 galaxies by\u0000Suwannajak, Tan, & Leroy (2014), we assess the shear dependence of SFE per\u0000orbital time ($epsilon_mathrm{orb}$) in 49 galaxies selected from the\u0000PHANGS-ALMA survey. In particular, we test a prediction of the shear-driven GMC\u0000collision model that $epsilon_mathrm{orb}propto(1-0.7beta)$, where\u0000$betaequiv{d}:mathrm{ln}:v_mathrm{circ}/d:mathrm{ln}:r$, i.e., SFE per\u0000orbital time declines with decreasing shear. We fit the function\u0000$epsilon_mathrm{orb}=epsilon_mathrm{orb,,0}(1-alpha_mathrm{CC}beta)$\u0000finding $alpha_mathrm{CC}simeq0.76pm0.16$; an alternative fit with\u0000$epsilon_mathrm{orb}$ normalized by the median value in each galaxy yields\u0000$alpha_mathrm{CC}^*=0.80pm0.15$. These results are in good agreement with\u0000the prediction of the shear-driven GMC collision theory. We also examine the\u0000impact of a galactic bar on $epsilon_mathrm{orb}$ finding a modest decrease\u0000in SFE in the presence of bar, which can be attributed to lower rates of shear\u0000in these regions. We discuss the implications of our results for the GMC life\u0000cycle and environmental dependence of star formation activity.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195362","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}