Hsi-An Pan
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View article: Masses, Star Formation Efficiencies, and Dynamical Evolution of 18,000 H <scp>ii</scp> Regions
Masses, Star Formation Efficiencies, and Dynamical Evolution of 18,000 H <span>ii</span> Regions Open
We present measurements of the masses associated with ∼18,000 H ii regions across 19 nearby star-forming galaxies by combining data from JWST, Hubble Space Telescope, MUSE, Atacama Large Millimeter/submillimeter Array, Very Large Arra…
View article: The PHANGS-MUSE/HST-Halpha Nebulae Catalogue
The PHANGS-MUSE/HST-Halpha Nebulae Catalogue Open
We present the PHANGS-MUSE/HST-Halpha nebulae catalogue, comprising 5177 spatially resolved nebulae across 19 nearby star-forming galaxies (< 20 Mpc), based on high-resolution Halpha imaging from HST, homogenised to a fixed 10 pc resolutio…
View article: Polycyclic aromatic hydrocarbon destruction in star-forming regions across 42 nearby galaxies
Polycyclic aromatic hydrocarbon destruction in star-forming regions across 42 nearby galaxies Open
Polycyclic aromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM) of near solar metallicity galaxies, where they play a critical role in ISM heating, cooling, and reprocessing stellar radiation. The PAH fraction, the …
View article: Characterization of Two Cool Galaxy Outflow Candidates Using Mid-infrared Emission from Polycyclic Aromatic Hydrocarbons
Characterization of Two Cool Galaxy Outflow Candidates Using Mid-infrared Emission from Polycyclic Aromatic Hydrocarbons Open
We characterize two candidate cool galactic outflows in two relatively low-mass, highly inclined Virgo cluster galaxies: NGC 4424 and NGC 4694. Previous analyses of observations using the Atacama Large Millimeter/submillimeter Array carbon…
View article: Masses, Star-Formation Efficiencies, and Dynamical Evolution of 18,000 HII Regions
Masses, Star-Formation Efficiencies, and Dynamical Evolution of 18,000 HII Regions Open
We present measurements of the masses associated with $\sim18,000$ HII regions across 19 nearby star-forming galaxies by combining data from JWST, HST, MUSE, ALMA, VLA, and MeerKAT from the multi-wavelength PHANGS survey. We report 10 pc-s…
View article: Physical Properties of Gas Departing from Circular Rotation at 50 pc Scales Using the PHANGS-MUSE Galaxies
Physical Properties of Gas Departing from Circular Rotation at 50 pc Scales Using the PHANGS-MUSE Galaxies Open
Noncircular (NC) motions have been observed across various spatial scales in disk galaxies, yet the physical properties of the gas involved in these motions remain poorly constrained. Using data from 19 galaxies from the PHANGS-MUSE sample…
View article: Polycyclic aromatic hydrocarbons destruction in star-forming regions across 42 nearby galaxies
Polycyclic aromatic hydrocarbons destruction in star-forming regions across 42 nearby galaxies Open
Polycyclic aromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM) of Solar metallicity galaxies, where they play a critical role in ISM heating, cooling, and reprocessing stellar radiation. The PAH fraction, the abund…
View article: Surveying the Whirlpool at Arcseconds with NOEMA (SWAN)
Surveying the Whirlpool at Arcseconds with NOEMA (SWAN) Open
Context. CO isotopologues are common tracers of the bulk molecular gas in extragalactic studies, providing insights into the physical and chemical conditions of the cold molecular gas, a reservoir for star formation. Aims. Since star forma…
View article: Characterization of Two Cool Galaxy Outflow Candidates Using Mid-Infrared Emission from Polycyclic Aromatic Hydrocarbons
Characterization of Two Cool Galaxy Outflow Candidates Using Mid-Infrared Emission from Polycyclic Aromatic Hydrocarbons Open
We characterize two candidate cool galactic outflows in two relatively low mass, highly inclined Virgo cluster galaxies: NGC4424 and NGC4694. Previous analyses of observations using the Atacama Large Millimeter Array (ALMA) carbon monoxide…
View article: The SWAN view of dense gas in the Whirlpool. A cloud-scale comparison of N2H+, HCO+, HNC, and HCN emission in M51
The SWAN view of dense gas in the Whirlpool. A cloud-scale comparison of N2H+, HCO+, HNC, and HCN emission in M51 Open
Tracing dense molecular gas, the fuel for star formation, is essential for understanding the evolution of molecular clouds and star-formation processes. We compared the emission of HCN (1-0), HNC (1-0), and with the emission of at cloud sc…
View article: Azimuthal offsets in spiral arms of nearby galaxies
Azimuthal offsets in spiral arms of nearby galaxies Open
Spiral arms play a central role in disc galaxies, but their dynamical nature remains a long-standing open question. Azimuthal offsets between molecular gas and star formation are expected if gas crosses spiral arms, as predicted by quasi-s…
View article: Constraining Resolved Extragalactic <i>R</i> <sub>21</sub> Variation with Well-calibrated ALMA Observations
Constraining Resolved Extragalactic <i>R</i> <sub>21</sub> Variation with Well-calibrated ALMA Observations Open
CO(1–0) and CO(2–1) are commonly used as bulk molecular gas tracers. The CO line ratios (especially CO(2–1)/CO(1–0)– R 21 ) vary within and among galaxies, yet previous studies on R 21 and alike often rely on measurements constructed by co…
View article: Constraining resolved extragalactic $R_{21}$ variation with well calibrated ALMA observations
Constraining resolved extragalactic $R_{21}$ variation with well calibrated ALMA observations Open
CO(1-0) and CO(2-1) are commonly used as bulk molecular gas tracers. The CO line ratios (especially CO(2-1)/CO(1-0) - $R_{21}$) vary within and among galaxies, yet previous studies on $R_{21}$ and alike often rely on measurements construct…
View article: Cloud-scale Gas Properties, Depletion Times, and Star Formation Efficiency per Freefall Time in PHANGS–ALMA
Cloud-scale Gas Properties, Depletion Times, and Star Formation Efficiency per Freefall Time in PHANGS–ALMA Open
We compare measurements of star formation efficiency to cloud-scale gas properties across the PHANGS– ALMA sample. Dividing 67 galaxies into 1.5 kpc scale regions, we calculate the molecular gas depletion time and the s…
View article: Polycyclic Aromatic Hydrocarbon and CO(2–1) Emission at 50–150 pc Scales in 70 Nearby Galaxies
Polycyclic Aromatic Hydrocarbon and CO(2–1) Emission at 50–150 pc Scales in 70 Nearby Galaxies Open
Combining Atacama Large Millimeter/submillimeter Array CO(2–1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2–1) and polycyclic aromatic hydrocarbon (PAH) emission at ≈100 pc resolution in 70…
View article: The resolved star-formation efficiency of early-type galaxies
The resolved star-formation efficiency of early-type galaxies Open
Understanding how and why star formation varies between galaxies is fundamental to our comprehension of galaxy evolution. In particular, the star-formation efficiency (SFE; star-formation rate or SFR per unit cold gas mass) has been shown …
View article: SDSS-IV MaNGA: Spatial Evolution of Gas-phase Metallicity Changes Induced by Galaxy Interactions
SDSS-IV MaNGA: Spatial Evolution of Gas-phase Metallicity Changes Induced by Galaxy Interactions Open
Gas-phase metallicity in interacting and merging galaxies offers key insights into their star formation processes and evolutionary histories. This study investigates the spatial evolution of gas-phase metallicity (i.e., oxygen abundance, 1…
View article: Surveying the Whirlpool at Arcseconds with NOEMA (SWAN)
Surveying the Whirlpool at Arcseconds with NOEMA (SWAN) Open
We present Surveying the Whirlpool at Arcseconds with NOEMA (SWAN), a high-resolution, high-sensitivity survey to map molecular lines in the 3 mm band in M51 (the Whirlpool galaxy). SWAN has obtained the largest high-sensitivity map (∼5 × …
View article: SDSS-IV MaNGA: Spatial Evolution of Gas-Phase Metallicity Changes Induced by Galaxy Interactions
SDSS-IV MaNGA: Spatial Evolution of Gas-Phase Metallicity Changes Induced by Galaxy Interactions Open
Gas-phase metallicity in interacting and merging galaxies offers key insights into their star formation processes and evolutionary histories. This study investigates the spatial evolution of gas-phase metallicity (i.e, oxygen abundance, 12…
View article: Cloud-scale gas properties, depletion times, and star formation efficiency per free-fall time in PHANGS--ALMA
Cloud-scale gas properties, depletion times, and star formation efficiency per free-fall time in PHANGS--ALMA Open
We compare measurements of star formation efficiency to cloud-scale gas properties across PHANGS-ALMA. Dividing 67 galaxies into 1.5 kpc scale regions, we calculate the molecular gas depletion time, tau_dep= Sigma_mol/Sigma_SFR, and the st…
View article: Dense gas scaling relations at kiloparsec scales across nearby galaxies with the ALMA ALMOND and IRAM 30 m EMPIRE surveys
Dense gas scaling relations at kiloparsec scales across nearby galaxies with the ALMA ALMOND and IRAM 30 m EMPIRE surveys Open
Dense, cold gas is the key ingredient for star formation. Over the last two decades, HCN(1 − 0) emission has been the most accessible dense gas tracer for studying external galaxies. We present new measurements that demonstrate the relatio…
View article: Dense gas scaling relations at kiloparsec scales across nearby galaxies with the ALMA ALMOND and IRAM 30m EMPIRE surveys
Dense gas scaling relations at kiloparsec scales across nearby galaxies with the ALMA ALMOND and IRAM 30m EMPIRE surveys Open
Dense, cold gas is the key ingredient for star formation. Over the last two decades, HCN(1-0) emission has been utilised as the most accessible dense gas tracer to study external galaxies. We present new measurements tracing the relationsh…
View article: CO Isotopologue-derived Molecular Gas Conditions and CO-to-H<sub>2</sub> Conversion Factors in M51
CO Isotopologue-derived Molecular Gas Conditions and CO-to-H<sub>2</sub> Conversion Factors in M51 Open
Over the past decade, several millimeter interferometer programs have mapped the nearby star-forming galaxy M51 at a spatial resolution of ≤170 pc. This study combines observations from three major programs: the PdBI Arcsecond Whirlpool Su…
View article: CO isotopologue-derived molecular gas conditions and CO-to-H$_2$ conversion factors in M51
CO isotopologue-derived molecular gas conditions and CO-to-H$_2$ conversion factors in M51 Open
Over the past decade, several millimeter interferometer programs have mapped the nearby star-forming galaxy M51 at a spatial resolution of ${\le}170$ pc. This study combines observations from three major programs: the PdBI Arcsecond Whirlp…
View article: Polycyclic Aromatic Hydrocarbon and CO(2-1) Emission at 50-150 pc Scales in 70 Nearby Galaxies
Polycyclic Aromatic Hydrocarbon and CO(2-1) Emission at 50-150 pc Scales in 70 Nearby Galaxies Open
Combining Atacama Large Millimeter/sub-millimeter Array CO(2-1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2-1) and polycyclic aromatic hydrocarbon (PAH) emission at ~100 pc resolution in 7…
View article: The properties and kinematics of HCN emission across the closest starburst galaxy NGC 253 observed with ALMA
The properties and kinematics of HCN emission across the closest starburst galaxy NGC 253 observed with ALMA Open
Context. Investigating molecular gas tracers, such as hydrogen cyanide (HCN), to probe higher densities than CO emission across nearby galaxies remains challenging. This is due to the large observing times required to detect HCN at a high …
View article: A 260 pc resolution ALMA map of HCN(1–0) in the galaxy NGC 4321
A 260 pc resolution ALMA map of HCN(1–0) in the galaxy NGC 4321 Open
The property of star formation rate (SFR) is tightly connected to the amount of dense gas in molecular clouds. However, it is not fully understood how the relationship between dense molecular gas and star formation varies within galaxies a…
View article: PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: Physical drivers of the molecular gas fraction, <i>R</i><sub>mol</sub>
PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: Physical drivers of the molecular gas fraction, <i>R</i><sub>mol</sub> Open
The molecular-to-atomic gas ratio is crucial to our understanding of the evolution of the interstellar medium (ISM) in galaxies. We investigated the balance between the atomic (Σ HI ) and molecular gas (Σ H2 ) surface densities in eight ne…
View article: Neutral atomic and molecular gas dynamics in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496
Neutral atomic and molecular gas dynamics in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496 Open
Neutral atomic gas (H I ) effectively traces galactic dynamics across mid to large galactocentric radii. However, its limitations in observing small-scale changes within the central few kiloparsecs, coupled with the often observed H I defi…
View article: PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: physical drivers of the molecular gas fraction, $R_{\mathrm{mol}}$
PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: physical drivers of the molecular gas fraction, $R_{\mathrm{mol}}$ Open
The molecular-to-atomic gas ratio is crucial to the evolution of the interstellar medium in galaxies. We investigate the balance between the atomic ($Σ_{\rm HI}$) and molecular gas ($Σ_{\rm H2}$) surface densities in eight nearby star-form…