scholarly journals PHANGS–ALMA: Arcsecond CO(2–1) Imaging of Nearby Star-forming Galaxies

2021 ◽  
Vol 257 (2) ◽  
pp. 43
Author(s):  
Adam K. Leroy ◽  
Eva Schinnerer ◽  
Annie Hughes ◽  
Erik Rosolowsky ◽  
Jérôme Pety ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Formation Rate ◽  
Sample Selection ◽  
Line Emission ◽  
Nearby Star ◽  
Very Large Array ◽  
Star Forming ◽  
Very Large Telescope ◽  
Public Data ◽  
Cold Star

Abstract We present PHANGS–ALMA, the first survey to map CO J = 2 → 1 line emission at ∼1″ ∼100 pc spatial resolution from a representative sample of 90 nearby (d ≲ 20 Mpc) galaxies that lie on or near the z = 0 “main sequence” of star-forming galaxies. CO line emission traces the bulk distribution of molecular gas, which is the cold, star-forming phase of the interstellar medium. At the resolution achieved by PHANGS–ALMA, each beam reaches the size of a typical individual giant molecular cloud, so that these data can be used to measure the demographics, life cycle, and physical state of molecular clouds across the population of galaxies where the majority of stars form at z = 0. This paper describes the scientific motivation and background for the survey, sample selection, global properties of the targets, Atacama Large Millimeter/submillimeter Array (ALMA) observations, and characteristics of the delivered data and derived data products. As the ALMA sample serves as the parent sample for parallel surveys with MUSE on the Very Large Telescope, the Hubble Space Telescope, AstroSat, the Very Large Array, and other facilities, we include a detailed discussion of the sample selection. We detail the estimation of galaxy mass, size, star formation rate, CO luminosity, and other properties, compare estimates using different systems and provide best-estimate integrated measurements for each target. We also report the design and execution of the ALMA observations, which combine a Cycle 5 Large Program, a series of smaller programs, and archival observations. Finally, we present the first 1″ resolution atlas of CO emission from nearby galaxies and describe the properties and contents of the first PHANGS–ALMA public data release.

scholarly journals Volumetric star formation laws of disc galaxies

2019 ◽  
Vol 622 ◽  
pp. A64 ◽  
Author(s):  
Cecilia Bacchini ◽  
Filippo Fraternali ◽  
Giuliano Iorio ◽  
Gabriele Pezzulli
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Formation Rate ◽  
Three Dimensional ◽  
Gas Content ◽  
Nearby Star ◽  
Star Forming ◽  
Good Tracer ◽  
Cold Star ◽  
Disc Galaxies

Star formation (SF) laws are fundamental relations between the gas content of a galaxy and its star formation rate (SFR) and play key roles in galaxy evolution models. In this paper, we present new empirical SF laws of disc galaxies based on volume densities. Following the assumption of hydrostatic equilibrium, we calculated the radial growth of the thickness of the gaseous discs in the combined gravitational potential of dark matter, stars, and gas for 12 nearby star-forming galaxies. This allowed us to convert the observed surface densities of gas and SFR into the deprojected volume densities. We found a tight correlation with slope in the range 1.3–1.9 between the volume densities of gas (HI+H2) and the SFR with a significantly smaller scatter than the surface-based (Kennicutt) law and no change in the slope over five orders of magnitude. This indicates that taking into account the radial increase of the thickness of galaxy discs is crucial to reconstruct their three-dimensional density profiles, in particular in their outskirts. Moreover, our result suggests that the break in the slope seen in the Kennicutt law is due to disc flaring rather than to a drop of the SF efficiency at low surface densities. Surprisingly, we discovered an unexpected correlation between the volume densities of HI and SFR, indicating that the atomic gas is a good tracer of the cold star-forming gas, especially in low density HI-dominated environments.

scholarly journals Gemini IFU, VLA, and HST observations of the OH Megamaser Galaxy IRAS17526 + 3253★

2019 ◽  
Vol 486 (3) ◽  
pp. 3350-3367 ◽  
Author(s):  
Dinalva A Sales ◽  
A Robinson ◽  
R A Riffel ◽  
T Storchi-Bergmann ◽  
J F Gallimore ◽  
...  
Keyword(s):  
Star Formation ◽  
Hubble Space Telescope ◽  
Formation Rate ◽  
Line Emission ◽  
Ionization Source ◽  
Space Telescope ◽  
Star Forming ◽  
Star Forming Regions ◽  
Major Merger ◽  
Field Unit

AbstractWe present a multiwavelength study of the OH megamaser galaxy IRAS17526 + 3253, based on new Gemini multi-object spectrograph integral field unit (GMOS/IFU) observations, Hubble Space Telescope F814W, and H α + [N ii] images, and archival 2MASS and 1.49 GHz VLA data. The Hubble Space Telescope(HST) images clearly reveal a mid-to-advanced stage major merger whose northwestern and southeastern nuclei have a projected separation of ∼8.5 kpc. Our HST/H α + [N ii] image shows regions of ongoing star formation across the envelope on ∼10 kpc scales, which are aligned with radio features, supporting the interpretation that the radio emission originates from star-forming regions. The measured H α luminosities imply that the unobscured star formation rate (SFR) is ∼10–30 M⊙ yr−1. The GMOS/IFU data reveal two structures in northwestern separated by 850 pc and by a discontinuity in the velocity field of ∼ 200 km s−1. We associate the blueshifted and redshifted components with, respectively, the distorted disc of northwestern and tidal debris, possibly a tail originating in southeastern. Star formation is the main ionization source in both components, which have SFRs of ∼2.6–7.9 M⊙ yr−1 and ∼1.5–4.5 M⊙ yr−1, respectively. Fainter line emission bordering these main components is consistent with shock ionization at a velocity ∼200 km s−1 and may be the result of an interaction between the tidal tail and the northwestern galaxy’s disc. IRAS17526 + 3253 is one of only a few systems known to host both luminous OH and H2O masers. The velocities of the OH and H2O maser lines suggest that they are associated with the northwestern and southeastern galaxies, respectively (Martin et al.; Wagner).

scholarly journals Morphometry as a probe of the evolution of jellyfish galaxies: evidence of broadening in the surface brightness profiles of ram-pressure stripping candidates in the multicluster system A901/A902

2020 ◽  
Vol 500 (1) ◽  
pp. 40-53
Author(s):  
Fernanda Roman-Oliveira ◽  
Ana L Chies-Santos ◽  
Fabricio Ferrari ◽  
Geferson Lucatelli ◽  
Bruno Rodríguez Del Pino
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Quantitative Measurement ◽  
Star Formation Rate ◽  
Hubble Space Telescope ◽  
Formation Rate ◽  
Structural Evolution ◽  
Star Forming ◽  
Irregular Structures ◽  
Ram Pressure

ABSTRACT We explore the morphometric properties of a group of 73 ram-pressure stripping candidates in the A901/A902 multicluster system, at z∼ 0.165, to characterize the morphologies and structural evolution of jellyfish galaxies. By employing a quantitative measurement of morphometric indicators with the algorithm morfometryka on Hubble Space Telescope (F606W) images of the galaxies, we present a novel morphology-based method for determining trail vectors. We study the surface brightness profiles and curvature of the candidates and compare the results obtained with two analysis packages, morfometryka and iraf/ellipse on retrieving information of the irregular structures present in the galaxies. Our morphometric analysis shows that the ram-pressure stripping candidates have peculiar concave regions in their surface brightness profiles. Therefore, these profiles are less concentrated (lower Sérsic indices) than other star-forming galaxies that do not show morphological features of ram-pressure stripping. In combination with morphometric trail vectors, this feature could both help identify galaxies undergoing ram-pressure stripping and reveal spatial variations in the star formation rate.

Multiwavelength analysis of OH Megamaser galaxies: The case of IRAS11506-3851

2020 ◽  
Vol 15 (S359) ◽  
pp. 347-349
Author(s):  
Carpes P. Hekatelyne ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Active Galactic Nuclei ◽  
Hubble Space Telescope ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Star Forming Regions ◽  
Field Unit ◽  
Mixed Transition ◽  
Integral Field

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.

scholarly journals The Star Formation Reference Survey. IV. Stellar mass distribution of local star-forming galaxies

2021 ◽  
Author(s):  
P Bonfini ◽  
A Zezas ◽  
M L N Ashby ◽  
S P Willner ◽  
A Maragkoudakis ◽  
...  
Keyword(s):  
Star Formation ◽  
Mass Distribution ◽  
Star Formation Rate ◽  
Mass Density ◽  
Full Range ◽  
Formation Rate ◽  
Stellar Mass ◽  
Nearby Star ◽  
Star Forming ◽  
Mass Functions

Abstract We constrain the mass distribution in nearby, star-forming galaxies with the Star Formation Reference Survey (SFRS), a galaxy sample constructed to be representative of all known combinations of star formation rate (SFR), dust temperature, and specific star formation rate (sSFR) that exist in the Local Universe. An innovative two-dimensional bulge/disk decomposition of the 2MASS/Ks-band images of the SFRS galaxies yields global luminosity and stellar mass functions, along with separate mass functions for their bulges and disks. These accurate mass functions cover the full range from dwarf galaxies to large spirals, and are representative of star-forming galaxies selected based on their infra-red luminosity, unbiased by AGN content and environment. We measure an integrated luminosity density j = 1.72 ± 0.93 × 109 L⊙  h−1 Mpc−3 and a total stellar mass density ρM = 4.61 ± 2.40 × 108 M⊙  h−1 Mpc−3. While the stellar mass of the average star-forming galaxy is equally distributed between its sub-components, disks globally dominate the mass density budget by a ratio 4:1 with respect to bulges. In particular, our functions suggest that recent star formation happened primarily in massive systems, where they have yielded a disk stellar mass density larger than that of bulges by more than 1 dex. Our results constitute a reference benchmark for models addressing the assembly of stellar mass on the bulges and disks of local (z = 0) star-forming galaxies.

scholarly journals Simulations of the star-forming molecular gas in an interacting M51-like galaxy

2020 ◽  
Vol 492 (2) ◽  
pp. 2973-2995 ◽  
Author(s):  
Robin G Tress ◽  
Rowan J Smith ◽  
Mattia C Sormani ◽  
Simon C O Glover ◽  
Ralf S Klessen ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Three Dimensional ◽  
Molecular Gas ◽  
Secondary Importance ◽  
Star Forming ◽  
The Galaxy ◽  
Cold Star ◽  
Self Gravity

ABSTRACT We present here the first of a series of papers aimed at better understanding the evolution and properties of giant molecular clouds (GMCs) in a galactic context. We perform high-resolution, three-dimensional arepo simulations of an interacting galaxy inspired by the well-observed M51 galaxy. Our fiducial simulations include a non-equilibrium, time-dependent, chemical network that follows the evolution of atomic and molecular hydrogen as well as carbon and oxygen self-consistently. Our calculations also treat gas self-gravity and subsequent star formation (described by sink particles), and coupled supernova feedback. In the densest parts of the simulated interstellar medium (ISM), we reach sub-parsec resolution, granting us the ability to resolve individual GMCs and their formation and destruction self-consistently throughout the galaxy. In this initial work, we focus on the general properties of the ISM with a particular focus on the cold star-forming gas. We discuss the role of the interaction with the companion galaxy in generating cold molecular gas and controlling stellar birth. We find that while the interaction drives large-scale gas flows and induces spiral arms in the galaxy, it is of secondary importance in determining gas fractions in the different ISM phases and the overall star formation rate. The behaviour of the gas on small GMC scales instead is mostly controlled by the self-regulating property of the ISM driven by coupled feedback.

scholarly journals A Herschel Survey of the [N ii] 205 μm Emission in Local Infrared Luminous Galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 256-256
Author(s):  
Yinghe Zhao ◽  
Nanyao Lu ◽  
C. Kevin Xu ◽  
Yu Gao ◽  
Keyword(s):  
Statistical Study ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Line Emission ◽  
Infrared Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
High Ionization ◽  
Luminous Galaxies ◽  
Ionization Parameter

AbstractThe [N ii] line is a major coolant in ionized interstellar medium, and is expected to be a good star formation rate indicator. Here we present a statistical study of [N ii] line emission for a large sample of local luminous infrared galaxies (LIRGs) using Herschel SPIRE FTS data (Lu et al. 2012; Zhao et al. 2012, in preparation). For our sample of galaxies, the [N ii] to the total infrared luminosity ratio (L[Nii]/LIR) varies from ∼ 10−5 to ∼ 10−4. We investigate the correlation between L[Nii] and LIR, as well as the dependence of L[Nii]/LIR on LIR, infrared colors (f60/f100) and the OIII 88 μm to [N ii] luminosity ratio. We find that L[Nii] strongly, and almost linearly correlates with LIR for star-forming galaxies, namely log LIR = (4.23 ± 0.33) + (0.99 ± 0.05) log L[NII] (see Fig. 1). The scatter in this relation is mainly due to the variation of hardness, and/or high ionization parameter, of the background UV field.

scholarly journals A MUSE inquiry into the physical processes taking place within the Abell 2667 Brightest Cluster Galaxy

2019 ◽  
Vol 15 (S341) ◽  
pp. 83-87
Author(s):  
E. Iani ◽  
G. Rodighiero ◽  
J. Fritz ◽  
G. Cresci ◽  
C. Mancini ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Resolving Power ◽  
Mass Star ◽  
Physical Processes ◽  
Cluster Galaxy ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Cold Star ◽  
Field Unit

AbstractBrightest cluster galaxies (BCGs) residing in cool-core clusters are known to be the stage of intricate baryon cycle phenomena (e.g. gas inflows, AGN outflows, star formation feedback). The scenarios describing the observed properties of these galaxies are still controversial, suffering from limitations due to the spatial resolving power of the instruments, specifically for galaxies beyond the Local Universe. However, the dramatic improvements introduced by the integral-field unit instruments (e.g. MUSE) could shed light on the physical processes driving the evolution of these galaxies. We present an extensive analysis of the stellar and gas properties (i.e. kinematics, stellar mass, star formation rate) of the radio-loud BCG sitting at the centre of the X-ray luminous cool-core cluster Abell 2667 (z = 0.23), based on MUSE data. Our results indicate that the BCG is a massive elliptical, hosting an AGN that is possibly undergoing accretion of cold star-forming clouds of ICM or galactic cannibalism.

scholarly journals PHIBSS2: survey design and z = 0.5 – 0.8 results

2019 ◽  
Vol 622 ◽  
pp. A105 ◽  
Author(s):  
J. Freundlich ◽  
F. Combes ◽  
L. J. Tacconi ◽  
R. Genzel ◽  
S. Garcia-Burillo ◽  
...  
Keyword(s):  
Star Formation ◽  
Survey Design ◽  
Formation Rate ◽  
Sample Selection ◽  
Stellar Mass ◽  
Gas Content ◽  
Molecular Gas ◽  
Star Forming ◽  
Gas Measurements ◽  
Deep Fields

Following the success of the Plateau de Bure high-z Blue Sequence Survey (PHIBSS), we present the PHIBSS2 legacy program, a survey of the molecular gas properties of star-forming galaxies on and around the star-formation main sequence (MS) at different redshifts using IRAM’s NOrthern Extended Millimeter Array (NOEMA). This survey significantly extends the existing sample of star-forming galaxies with CO molecular gas measurements, probing the peak epoch of star formation (z = 1 − 1.6) as well as its building-up (z = 2 − 3) and winding-down (z = 0.5 − 0.8) phases. The targets are drawn from the well-studied GOODS, COSMOS, and AEGIS cosmological deep fields and uniformly sample the MS in the stellar mass (M⋆) – star formation rate (SFR) plane with log(M⋆/M⊙) = 10 − 11.8 and SFR = 3.5 − 500 M⊙ yr−1 without morphological selection, thus providing a statistically meaningful census of star-forming galaxies at different epochs. We describe the survey strategy and sample selection before focusing on the results obtained at redshift z = 0.5 − 0.8, where we report 60 CO(2-1) detections out of 61 targets. We determine molecular gas masses between 2 × 109 and 5 × 1010 M⊙ and separately obtain disc sizes and bulge-to-total (B/T) luminosity ratios from HST I-band images. The median molecular gas-to-stellar mass ratio μgas∼ = 0.28 ± 0.04, gas fraction fgas∼ = 0.22 ± 0.02, and depletion time $ \widetilde{t_{\mathrm{depl}}} = 0.84 \pm 0.07\,\mathrm{Gyr} $ as well as their dependence with stellar mass and offset from the MS follow published scaling relations for a much larger sample of galaxies spanning a significantly wider range of redshifts, the cosmic evolution of the SFR being mainly driven by that of the molecular gas fraction. The galaxy-averaged molecular Kennicutt–Schmidt (KS) relation between molecular gas and SFR surface densities is strikingly linear, pointing towards similar star formation timescales within galaxies at any given epoch. In terms of morphology, the molecular gas content, the SFR, the disc stellar mass, and the disc molecular gas fraction do not seem to correlate with B/T and the stellar surface density, which suggests an ongoing supply of fresh molecular gas to compensate for the build-up of the bulge. Our measurements do not yield any significant variation of the depletion time with B/T and hence no strong evidence for morphological quenching within the scatter of the MS.

scholarly journals Distances to PHANGS Galaxies: New Tip of the Red Giant Branch Measurements and Adopted Distances

2020 ◽  
Author(s):  
Gagandeep S Anand ◽  
Janice C Lee ◽  
Schuyler D Van Dyk ◽  
Adam K Leroy ◽  
Erik Rosolowsky ◽  
...  
Keyword(s):  
First Year ◽  
Physical Parameters ◽  
H Ii Regions ◽  
Star Clusters And Associations ◽  
Distance Measurements ◽  
Nearby Star ◽  
Star Forming ◽  
Public Data ◽  
The Galaxy ◽  
Red Giant

Abstract PHANGS-HST is an ultraviolet-optical imaging survey of 38 spiral galaxies within ∼20 Mpc. Combined with the PHANGS-ALMA, PHANGS-MUSE surveys and other multiwavelength data, the dataset will provide an unprecedented look into the connections between young stars, H ii regions, and cold molecular gas in these nearby star-forming galaxies. Accurate distances are needed to transform measured observables into physical parameters (e.g., brightness to luminosity, angular to physical sizes of molecular clouds, star clusters and associations). PHANGS-HST has obtained parallel ACS imaging of the galaxy halos in the F606W and F814W bands. Where possible, we use these parallel fields to derive tip of the red giant branch (TRGB) distances to these galaxies. In this paper, we present TRGB distances for 11 galaxies from ∼4 to ∼15 Mpc, based on the first year of PHANGS-HST observations. Five of these represent the first published TRGB distance measurements (IC 5332, NGC 2835, NGC 4298, NGC 4321, and NGC 4328), and eight of which are the best available distances to these targets. We also provide a compilation of distances for the 118 galaxies in the full PHANGS sample, which have been adopted for the first PHANGS-ALMA public data release.

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