scholarly journals Stochastic 2-D Models of Galaxy Disk Evolution. The Galaxy M33

2014 ◽  
Vol 23 (3-4) ◽  
Author(s):  
T. Mineikis ◽  
V. Vansevičius
Keyword(s):  
Star Formation ◽  
Parameter Space ◽  
Surface Density ◽  
Surface Brightness ◽  
Radial Profiles ◽  
The Galaxy ◽  
Galaxy Disk ◽  
Disk Evolution ◽  
Density Surface ◽  
D Model

AbstractWe have developed a fast numerical 2-D model of galaxy disk evolution (resolved along the galaxy radius and azimuth) by adopting a scheme of parameterized stochastic self-propagating star formation. We explore the parameter space of the model and demonstrate its capability to reproduce 1-D radial profiles of the galaxy M33: gas surface density, surface brightness in the

scholarly journals The star formation history of galaxies in 3D: CALIFA perspective

2014 ◽  
Vol 10 (S309) ◽  
pp. 99-104
Author(s):  
R. M. González Delgado ◽  
R. Cid Fernandes ◽  
R. García-Benito ◽  
E. Pérez ◽  
A. L. de Amorim ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Spectral Synthesis ◽  
Stellar Mass ◽  
Star Formation History ◽  
Chemical Enrichment ◽  
Radial Profiles ◽  
Formation History ◽  
The Galaxy ◽  
History Of

AbstractWe resolve spatially the star formation history of 300 nearby galaxies from the CALIFA integral field survey to investigate: a) the radial structure and gradients of the present stellar populations properties as a function of the Hubble type; and b) the role that plays the galaxy stellar mass and stellar mass surface density in governing the star formation history and metallicity enrichment of spheroids and the disks of galaxies. We apply the fossil record method based on spectral synthesis techniques to recover spatially and temporally resolved maps of stellar population properties of spheroids and spirals with galaxy mass from 109 to 7×1011 M⊙. The individual radial profiles of the stellar mass surface density (μ⋆), stellar extinction (AV), luminosity weighted ages (〈logage〉L), and mass weighted metallicity (〈log Z/Z⊙〉M) are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). All these properties show negative gradients as a sight of the inside-out growth of massive galaxies. However, the gradients depend on the Hubble type in different ways. For the same galaxy mass, E and S0 galaxies show the largest inner gradients in μ⋆; and Andromeda-like galaxies (Sb with log M⋆ (M⊙) ∼ 11) show the largest inner age and metallicity gradients. In average, spiral galaxies have a stellar metallicity gradient ∼ −0.1 dex per half-light radius, in agreement with the value estimated for the ionized gas oxygen abundance gradient by CALIFA. A global (M⋆-driven) and local (μ⋆-driven) stellar metallicity relation are derived. We find that in disks, the stellar mass surface density regulates the stellar metallicity; in spheroids, the galaxy stellar mass dominates the physics of star formation and chemical enrichment.

The Hi Neighborhoods Around STARBIRDS

2018 ◽  
Vol 14 (S344) ◽  
pp. 280-282
Author(s):  
Megan C. Johnson ◽  
Kristen B. W. McQuinn ◽  
John Cannon ◽  
Charlotte Martinkus ◽  
Evan Skillman ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Neutral Hydrogen ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Green Bank Telescope ◽  
Intense Star Formation

AbstractStarbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.

scholarly journals Measuring Outer Disk Warps with Optical Spectroscopy

2008 ◽  
Vol 4 (S254) ◽  
pp. 283-288
Author(s):  
Daniel Christlein ◽  
Joss Bland-Hawthorn
Keyword(s):  
Star Formation ◽  
Optical Spectroscopy ◽  
Column Density ◽  
Rotational Velocity ◽  
Chemical Abundances ◽  
Circular Velocity ◽  
Outer Disk ◽  
The Galaxy ◽  
Galaxy Disk ◽  
Interesting Alternative

AbstractWarps in the outer gaseous disks of galaxies are a ubiquitous phenomenon, but it is still unclear what generates them. One theory is that warps are generated internally through spontaneous bending instabilities. Other theories suggest that they result from the interaction of the outer disk with accreting extragalactic material. In this case, we expect to find cases where the circular velocity of the warp gas is poorly correlated with the rotational velocity of the galaxy disk at the same radius. Optical spectroscopy presents itself as an interesting alternative to 21-cm observations for testing this prediction, because (i) separating the kinematics of the warp from those of the disk requires a spatial resolution that is higher than what is achieved at 21 cm at low HI column density; (ii) optical spectroscopy also provides important information on star formation rates, gas excitation, and chemical abundances, which provide clues to the origin of the gas in warps. We present here preliminary results of a study of the kinematics of gas in the outer-disk warps of seven edge-on galaxies, using multi-hour VLT/FORS2 spectroscopy.

scholarly journals The evolution of the spiral galaxy M51a

2015 ◽  
Vol 11 (S319) ◽  
pp. 129-129
Author(s):  
Xiaoyu Kang ◽  
Fenghui Zhang ◽  
Ruixiang Chang
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Evolutionary History ◽  
Surface Brightness ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Molecular Gas ◽  
Peak Time ◽  
Model Predictions ◽  
Inside Out

AbstractA simple model for M51a is constructed to explore its evolutionary history by assuming its disk grows from continuous gas infall, which is shaped by a free parameter-the infall-peak time tp. By adopting a constant infall-peak time tp = 7.0Gyr, our model predictions can reproduce most of the observed constraints and still show that the disk of M51a forms inside-out. Our results also show that the current molecular gas surface density, the star-formation rate and the UV-band surface brightness are important quantities to trace the effect of recent interactions on galactic star-formation process.

scholarly journals Dependence of radio halos on underlying star formation activity and galaxy mass

2006 ◽  
Vol 2 (S237) ◽  
pp. 441-441
Author(s):  
U. Lisenfeld ◽  
M. Dahlem ◽  
J. Rossa
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Surface Density ◽  
Energy Input ◽  
Radio Continuum ◽  
Unit Surface Area ◽  
Related Energy ◽  
Star Formation Activity ◽  
The Galaxy ◽  
Radio Halos

AbstractWe investigate the relation between the existence and size of radio halos, which are believed to be created by star formation (SF) related energy input into the interstellar medium, and other galaxy properties, most importantly star formation activity and galaxy mass. Based on radio continuum and Hα observations of a sample of seven galaxies we find a direct, linear correlation of the radial extent of gaseous halos on the size of the actively star-forming parts of the galaxy disks. Data of a larger sample of 22 galaxies indicate that the threshold energy input rate into the disk ISM per unit surface area for the creation of a gaseous halo depends on the mass surface density of the galaxy, in the sense that a higher (lower) threshold has to be surpassed for galaxies with a higher (lower) surface density. Because of the good prediction of the existence of a radio halo from these two parameters, we conclude that they are important, albeit not the only contributors. The compactness of the SF-related energy input is also found to be a relevant factor. Galaxies with relatively compact SF distributions are more likely to have gaseous halos than others with more widespread SF activity. These results quantify the so-called “break-out” condition for matter to escape from galaxy disks, as used in all current models of the interstellar medium.More details can be found Dahlem, Lisenfeld & Rossa, 2006, A&A 457, 121.

scholarly journals Dissecting the Local Environment of FRB 190608 in the Spiral Arm of its Host Galaxy

2021 ◽  
Vol 922 (2) ◽  
pp. 173
Author(s):  
Jay S. Chittidi ◽  
Sunil Simha ◽  
Alexandra Mannings ◽  
J. Xavier Prochaska ◽  
Stuart D. Ryder ◽  
...  
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Surface Brightness ◽  
Local Environment ◽  
Host Galaxy ◽  
Dispersion Measure ◽  
Wide Field ◽  
Resonance Theory ◽  
The Galaxy ◽  
Spiral Arm

Abstract We present a high-resolution analysis of the host galaxy of fast radio burst (FRB) 190608, an SB(r)c galaxy at z = 0.11778 (hereafter HG 190608), to dissect its local environment and its contributions to the FRB properties. Our Hubble Space Telescope Wide Field Camera 3 ultraviolet and visible light image reveals that the subarcsecond localization of FRB 190608 is coincident with a knot of star formation (ΣSFR = 1.5 × 10−2 M ⊙ yr−1 kpc−2) in the northwest spiral arm of HG 190608. Using Hβ emission present in our Keck Cosmic Web Imager integral field spectrum of the galaxy with a surface brightness of μ H β = ( 3.36 ± 0.21 ) × 10 − 17 erg s − 1 cm − 2 arcsec − 2 , we infer an extinction-corrected Hα surface brightness and compute a dispersion measure (DM) from the interstellar medium of HG 190608 of DMHost,ISM = 94 ± 38 pc cm−3. The galaxy rotates with a circular velocity v circ = 141 ± 8 km s−1 at an inclination i gas = 37° ± 3°, giving a dynamical mass M halo dyn ≈ 10 11.96 ± 0.08 M ⊙ . This implies a halo contribution to the DM of DMHost,Halo = 55 ± 25 pc cm−3 subject to assumptions on the density profile and fraction of baryons retained. From the galaxy rotation curve, we infer a bar-induced pattern speed of Ω p = 34 ± 6 km s−1 kpc−1 using linear resonance theory. We then calculate the maximum time since star formation for a progenitor using the furthest distance to the arm’s leading edge within the localization, and find t enc = 21 − 6 + 25 Myr. Unlike previous high-resolution studies of FRB environments, we find no evidence of disturbed morphology, emission, or kinematics for FRB 190608.

scholarly journals Star-forming complexes in the polar ring galaxy NGC660

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Ksenia I. Smirnova ◽  
Dmitri S. Wiebe ◽  
Alexei V. Moiseev
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Star Forming ◽  
Polar Ring ◽  
Star Forming Regions ◽  
Disk Star ◽  
Dust Mass ◽  
The Galaxy ◽  
Galaxy Disk

AbstractGalaxies with polar rings consist of two subsystems, a disk and a ring, which rotate almost in orthogonal planes. In this paper, we analyze the parameters characterizing the composition of the interstellar medium and star formation in star-forming complexes belonging to polar ring galaxy NGC660. We show that star-forming regions in the ring of the galaxy are distinctly different from those in the galaxy disk. They possess substantially lower infrared luminosities, which is indicative of less dust mass in these regions than in a typical disk star-forming region. UV and Hα luminosities also appear to be lower in the ring, which is likely a consequence of its relatively recent formation.

The Structure of the Superthin Spiral Galaxy UGC7321

1999 ◽  
Vol 171 ◽  
pp. 207-209
Author(s):  
L.D. Matthews ◽  
J.S. Gallagher ◽  
W. van Driel
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Surface Brightness ◽  
Scale Height ◽  
Vertical Scale ◽  
Low Surface Brightness ◽  
Galaxy Disk ◽  
Color Gradients

AbstractUGC 7321 is an edge-on low surface brightness (LSB) spiral galaxy with a number of extraordinary properties. Its vertical scale height (~70 pc) is one of the smallest ever measured for a galaxy disk. Its disk also exhibits strong vertical and radial color gradients. UGC 7321 appears to be an extremely unevolved galaxy in both a dynamical and in a star-formation sense.

scholarly journals Star Formation in Tadpole Galaxies

2014 ◽  
Vol 1 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Casiana Muñoz-Tuñon ◽  
Jorge Sanchez Almeida ◽  
Debra M. Elmegreen ◽  
Bruce G. Elmegreen
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Star Forming ◽  
Spatially Resolved ◽  
Test Models ◽  
The Galaxy ◽  
Galaxy Disk ◽  
Tail Structure ◽  
Remarkable Result

Tadpole Galaxies look like a star forming head with a tail structure to the side. They are also named cometaries. In a series of recent works we have discovered a number of issues that lead us to consider them extremely interesting targets. First, from images, they are disks with a lopsided starburst. This result is rmly  established with long slit spectroscopy in a nearby representative sample. They rotate with the head following the rotation pattern but displaced from the rotation center. Moreover, in a search for extremely metal poor (XMP) galaxies, we identied tadpoles as the dominant shapes in the sample - nearly 80% of the local XMP galaxies have a tadpole morphology. In addition, the spatially resolved analysis of the metallicity shows the remarkable result that there is a metallicity drop right at the position of the head. This is contrary to what intuition would say and dicult to explain if star formation has happened from gas processed in the disk. The result could however be understood if the star formation is driven by pristine gas falling into the galaxy disk. If conrmed, we could be unveiling, for the rst time, cool  ows in action in our nearby world. The tadpole class is relatively frequent at high redshift - 10% of resolvable galaxies in the Hubble UDF but less than 1% in the local Universe. They are systems that could track cool ows and test models of galaxy formation.

scholarly journals Star Formation Thresholds: The View from Inside the Galaxy

2015 ◽  
Vol 11 (S315) ◽  
pp. 183-190
Author(s):  
James Di Francesco
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Column Density ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Gould Belt ◽  
The Galaxy ◽  
Dynamical Properties ◽  
The Relationship

AbstractWe explore the relationship between the total gas surface density and star formation rate surface density, a.k.a., the “Kennicutt-Schmidt relation,” in a Galactic context. Specifically, we probe the origins of thresholds in the behaviour of the K-S relation at 10 M⊙ pc−2 and 100-200 M⊙ pc−2 using images from the Herschel Hi-GAL and Gould Belt surveys. In both cases, pervasive filamentary structures are seen, possibly due to turbulent motions. The Hi-GAL image supports the view that at ~10 M⊙ pc−2 gas becomes molecular, leading to the formation of clouds that harbour star formation. The GBS images suggest the 100-200 M⊙ pc−2 threshold originates from the nature of filaments being stable until a critical column density of ~160 M⊙ pc−2 is reached. Therefore, the transition between non-star-forming and star-forming gas in clouds (and galaxies) may be set universally by the dynamical properties of filaments.

Sign in / Sign up

Export Citation Format

Share Document