Frequency and nature of central molecular outflows in nearby star-forming disk galaxies

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.

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Multiwavelength Observations of Galactic Winds: Near and Far

Symposium - International Astronomical Union ◽

10.1017/s0074180900197736 ◽

2004 ◽

Vol 217 ◽

pp. 276-286

Author(s):

Sylvain Veilleux

Keyword(s):

High Redshift ◽

Critical Discussion ◽

Future Research ◽

Nearby Star ◽

Research Directions ◽

Star Forming ◽

Galactic Winds ◽

Future Research Directions ◽

Formation And Evolution ◽

High Redshift Universe

This paper provides a critical discussion of the observational evidence for winds in our own Galaxy, in nearby star-forming and active galaxies, and in the high-redshift universe. The implications of galactic winds on the formation and evolution of galaxies and the intergalactic medium are briefly discussed. A number of observational challenges are mentioned to inspire future research directions.

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The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs

The Astrophysical Journal ◽

10.3847/1538-4357/aab269 ◽

2018 ◽

Vol 858 (1) ◽

pp. 41 ◽

Cited By ~ 9

Author(s):

Zhoujian Zhang ◽

Michael C. Liu ◽

William M. J. Best ◽

Eugene A. Magnier ◽

Kimberly M. Aller ◽

...

Keyword(s):

Proper Motion ◽

Brown Dwarfs ◽

Classification Method ◽

Nearby Star ◽

Star Forming ◽

Star Forming Regions ◽

Ultracool Dwarfs ◽

Free Classification

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The lifecycle of molecular clouds in nearby star-forming disc galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3525 ◽

2019 ◽

Vol 493 (2) ◽

pp. 2872-2909 ◽

Cited By ~ 44

Author(s):

Mélanie Chevance ◽

J M Diederik Kruijssen ◽

Alexander P S Hygate ◽

Andreas Schruba ◽

Steven N Longmore ◽

...

Keyword(s):

Star Formation ◽

Flux Ratio ◽

Molecular Gas ◽

H Ii Regions ◽

Dynamical Processes ◽

Nearby Star ◽

Star Forming ◽

Spatially Resolved ◽

Stellar Feedback ◽

Disc Galaxies

ABSTRACT It remains a major challenge to derive a theory of cloud-scale ($\lesssim100$ pc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of robust empirical constraints on the giant molecular cloud (GMC) lifecycle. We address this problem by systematically applying a new statistical method for measuring the evolutionary timeline of the GMC lifecycle, star formation, and feedback to a sample of nine nearby disc galaxies, observed as part of the PHANGS-ALMA survey. We measure the spatially resolved (∼100 pc) CO-to-H α flux ratio and find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. GMC lifetimes are short, typically $10\!-\!30\,{\rm Myr}$, and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities $\Sigma _{\rm H_2}\ge 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$, the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at $\Sigma _{\rm H_2}\le 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$ GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by H α (75–90 per cent of the cloud lifetime), GMCs disperse within just $1\!-\!5\,{\rm Myr}$ once massive stars emerge. The dispersal is most likely due to early stellar feedback, causing GMCs to achieve integrated star formation efficiencies of 4–10 per cent. These results show that galactic star formation is governed by cloud-scale, environmentally dependent, dynamical processes driving rapid evolutionary cycling. GMCs and H ii regions are the fundamental units undergoing these lifecycles, with mean separations of $100\!-\!300\,{{\rm pc}}$ in star-forming discs. Future work should characterize the multiscale physics and mass flows driving these lifecycles.

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The formation of discs in clusters

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310011531 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 771-771

Author(s):

Paul C. Clark

Keyword(s):

Local Density ◽

Cluster Formation ◽

Nearby Star ◽

Single Star ◽

Star Forming ◽

Central Object ◽

Star Forming Regions ◽

Time Period ◽

Particle Hydrodynamics ◽

Smoothed Particle

We review the properties of the discs that form around ‘sink particles’ in smoothed particle hydrodynamics (SPH) simulations of cluster formation, similar to those of Bate et al. (2003) and Bonnell et al. (2004), and compare them to the observed properties of discs in nearby star-forming regions. Contrary to previous suggestions, discs can form and survive in such an environment, despite the chaotic effects of competitive accretion. We find the discs are typically massive, with ratios of disc mass to central object mass of around 0.1, or higher, being typical. Naturally, the evolution of these discs is dominated by gravitational torques, and the more massive examples exhibit strong m=2 spiral modes. We also find that they can continuously grow over a period of 100,000 years, provided the central object is a single sink particle and the local density of sink particles is low. Discs that form around sink particles in the very centres of clusters tend to be shorter lived, but a single star can lose and gain a disc several times during the main accretion phase. However due to the nature of the turbulence in the cluster, the disc orientation can change dramatically over this time period, since disc-sink systems can accrete from counter-rotating envelopes. Since the competitive accretion process brings in material from large distances, the associated angular momentum can be higher than one would expect for an isolated star formation model. As such, we find that the discs are typically several hundred of AUs in extent, with the largest keplerian structures having radii of ~ 2000AU.

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A star-forming dwarf galaxy candidate in the halo of NGC 4634

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731304 ◽

2018 ◽

Vol 620 ◽

pp. A29 ◽

Cited By ~ 2

Author(s):

Y. Stein ◽

D. J. Bomans ◽

P. Kamphuis ◽

E. Jütte ◽

M. Langener ◽

...

Keyword(s):

Star Formation Rate ◽

Dwarf Galaxy ◽

Formation Rate ◽

Disk Galaxies ◽

Oxygen Abundance ◽

Star Forming ◽

The Galaxy ◽

Galaxy Disk ◽

Projected Distance

Context. The halos of disk galaxies form a crucial connection between the galaxy disk and the intergalactic medium. Massive stars, H II regions, or dwarf galaxies located in the halos of galaxies are potential tracers of recent accretion and/or outflows of gas, and are additional contributors to the photon field and the gas phase metallicity. Aims. We investigate the nature and origin of a star-forming dwarf galaxy candidate located in the halo of the edge-on Virgo galaxy NGC 4634 with a projected distance of 1.4 kpc and a Hα star formation rate of ∼4.7 × 10−3 M⊙ yr−1 in order to increase our understanding of these disk-halo processes. Methods. With optical long-slit spectra we measured fluxes of optical nebula emission lines to derive the oxygen abundance 12 + log(O/H) of an H II region in the disk of NGC 4634 and in the star-forming dwarf galaxy candidate. Abundances derived from optical long-slit data and from Hubble Space Telescope (HST) r-band data, Hα data, Giant Metrewave Radio Telescope (GMRT) H I data, and photometry of SDSS and GALEX data were used for further analysis. With additional probes of the luminosity–metallicity relation in the B-band from the Hα-luminosity, the H I map, and the relative velocities, we are able to constrain a possible origin of the dwarf galaxy candidate. Results. The high oxygen abundance (12 + log(O/H) ≈ 8.72) of the dwarf galaxy candidate leads to the conclusion that it was formed from pre-enriched material. Analysis of auxiliary data shows that the dwarf galaxy candidate is composed of material originating from NGC 4634. We cannot determine whether this material has been ejected tidally or through other processes, which makes the system highly interesting for follow up observations.

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A multi-phase model for simulations of galaxy formation

Symposium - International Astronomical Union ◽

10.1017/s0074180900207225 ◽

2003 ◽

Vol 208 ◽

pp. 273-282 ◽

Cited By ~ 1

Author(s):

Volker Springel ◽

Lars Hernquist

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Phase Structure ◽

Formation Rate ◽

Disk Galaxies ◽

Two Phase ◽

Star Forming ◽

Hot Gas ◽

Feedback Model ◽

Multi Phase

We discuss SPH simulations of galaxy formation which use a hybrid method to describe a two-phase structure of the star forming ISM on unresolved scales. Our modeling includes radiative cooling, heating due to a UV background, growth of cold clouds embedded in an ambient hot gas, star formation out of cloud material, feedback due to supernovae in the form of thermal heating and cloud evaporation, starbursts that can lead to galactic outflows, and metal enrichment. Our particular model for the treatment of the two-phase structure is based on a modified and extended version of the grid-based approach of Yepes et al. (1997). We discuss the properties of the feedback model and show how it stabilizes star forming disk galaxies and reduces the cosmic star formation rate to a level consistent with current observational constraints.

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