scholarly journals A phenomenological approach to the evolution of galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 141-150
Author(s):  
Simon J. Lilly ◽  
Yingjie Peng ◽  
Marcella Carollo ◽  
Alvio Renzini
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Statistical Data ◽  
Phenomenological Approach ◽  
Star Forming ◽  
Continuity Equations ◽  
The Galaxy ◽  
Star Formation In Galaxies ◽  
Galaxy Population

AbstractIncreasingly good statistical data on the galaxy population at high and low redshift enable the development of new phenomenological approaches to galaxy evolution based on application of the simplest continuity equations. This has given new insights into the different ways in which star-formation in galaxies is quenched, the role of merging in the population, and in to the control of star-formation in star-forming galaxies and the links with chemical evolution. The continuity approach provides a self-consistent view of the evolving population and exposes linkages between different aspects of galaxy evolution.

No evidence for quenching in quasars

2019 ◽  
Vol 15 (S359) ◽  
pp. 82-88
Author(s):  
Clare Wethers ◽  
Nischal Acharya ◽  
Roberto De Propris ◽  
Jari Kotilainen ◽  
Malte Schramm ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Host Galaxies ◽  
Dominant Effect ◽  
Broad Absorption ◽  
Broad Absorption Line ◽  
The Galaxy ◽  
Galaxy Population

AbstractThe role of quasar feedback in galaxy evolution remains poorly understood. Throughout this work, we explore the effects of negative feedback on star formation in quasar host galaxies, analysing two distinct populations of quasars. The first is a sample of high-redshift (z > 2) low-ionisation broad absorption line quasars (LoBALs) - a class of quasars hosting energetic mass outflows, in which we find evidence for prolific star formation (>750Mʘyr–1) exceeding that of non-BAL quasars at the same redshift. The second is a population of 207 low-redshift (z < 0.3) quasars, in which we find an enhancement in the SFRs of quasar hosts compared to the underlying galaxy population, with no quasars residing in quiescent hosts over the last 2Gyr. Overall, we find no evidence for galaxy-wide quenching in either population, rather we suggest that the dominant effect of quasar activity is to enhance star formation in the galaxy.

scholarly journals Redshift measurement through star formation

2019 ◽  
Vol 629 ◽  
pp. A7
Author(s):  
Mikkel O. Lindholmer ◽  
Kevin A. Pimbblet
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Main Sequence ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Star Forming ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

scholarly journals Study of a Complete Sample of Hα Emission–Line Galaxies from the UCM Survey

1996 ◽  
Vol 171 ◽  
pp. 380-380 ◽  
Author(s):  
J. Gallego ◽  
J. Zamorano ◽  
M. Rego ◽  
A.G. Vitores ◽  
O. Alonso
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Energy Output ◽  
University Of Michigan ◽  
Complete Sample ◽  
Star Forming ◽  
The Galaxy ◽  
Hα Emission ◽  
Emission Line Galaxies ◽  
Galaxy Population

The Universidad Complutense de Madrid survey is a long-term project with the aim of finding and analyzing star forming galaxies using the Hα line as the tracer for star formation processes. In order to obtain a representative and complete sample of the population detected, spectroscopic observations were carried out for the full sample of Hα emission-line galaxy (ELG) candidates of the UCM lists 1 and 2. The ELGs types most commonly found (47%) are intermediate to low-luminosity objects with a very intense star-formation region which dominates the optical energy output of the galaxy. This kind of ELGs is similar to the galaxy population detected in the blue objective-prism surveys. And what is more important, a second population (43%) of star-forming galaxies with low ionization or high extinction properties has been found. This ELGs group is detected neither in the blue (University of Michigan survey, Case survey) nor in other surveys (Kiso, IRAS, Markarian) using other selection techniques.

scholarly journals Milky Way analogues in MaNGA: multiparameter homogeneity and comparison to the Milky Way

2019 ◽  
Vol 491 (3) ◽  
pp. 3672-3701 ◽  
Author(s):  
N Boardman ◽  
G Zasowski ◽  
A Seth ◽  
J Newman ◽  
B Andrews ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Milky Way ◽  
Central Star ◽  
Stellar Kinematics ◽  
Star Forming ◽  
Wide Range ◽  
The Galaxy ◽  
Central Regions ◽  
Galaxy Population ◽  
Stellar Masses

ABSTRACT The Milky Way provides an ideal laboratory to test our understanding of galaxy evolution, owing to our ability to observe our Galaxy over fine scales. However, connecting the Galaxy to the wider galaxy population remains difficult, due to the challenges posed by our internal perspective and to the different observational techniques employed. Here, we present a sample of galaxies identified as Milky Way analogues on the basis of their stellar masses and bulge-to-total ratios, observed as part of the Mapping Nearby Galaxies at Apache Point Observatory survey. We analyse the galaxies in terms of their stellar kinematics and populations as well as their ionized gas contents. We find our sample to contain generally young stellar populations in their outskirts. However, we find a wide range of stellar ages in their central regions, and we detect central active galactic nucleus-like or composite-like activity in roughly half of the sample galaxies, with the other half consisting of galaxies with central star-forming emission or emission consistent with old stars. We measure gradients in gas metallicity and stellar metallicity that are generally flatter in physical units than those measured for the Milky Way; however, we find far better agreement with the Milky Way when scaling gradients by galaxies’ disc scale lengths. From this, we argue much of the discrepancy in metallicity gradients to be due to the relative compactness of the Milky Way, with differences in observing perspective also likely to be a factor.

scholarly journals xGASS: the role of bulges along and across the local star-forming main sequence

2020 ◽  
Vol 493 (4) ◽  
pp. 5596-5605 ◽  
Author(s):  
Robin H W Cook ◽  
Luca Cortese ◽  
Barbara Catinella ◽  
Aaron Robotham
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Local Universe ◽  
Star Forming ◽  
Star Formation Activity ◽  
The Galaxy ◽  
Stellar Masses

ABSTRACT We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the sSFR–M⋆ relation flattens by ∼0.1 dex per decade in M⋆ when re-normalizing specifice star formation rate (sSFR) by disc stellar mass instead of total stellar mass. However, recasting the sSFR–M⋆ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable scatter to that of the total galaxy relation. This suggests that the residual declining slope of the SFMS is intrinsic to the disc components of galaxies. We further investigate the distribution of bulge-to-total ratios (B/T) as a function of distance from the SFMS (ΔSFRMS). At all stellar masses, the average B/T of local galaxies decreases monotonically with increasing ΔSFRMS. Contrary to previous works, we find that the upper envelope of the SFMS is not dominated by objects with a significant bulge component. This rules out a scenario in which, in the local Universe, objects with increased star formation activity are simultaneously experiencing a significant bulge growth. We suggest that much of the discrepancies between different works studying the role of bulges originate from differences in the methodology of structurally decomposing galaxies.

scholarly journals Quasar Sightline and Galaxy Evolution (QSAGE) survey – I. The galaxy environment of O vi absorbers up to z = 1.4 around PKS 0232−04

2019 ◽  
Vol 486 (1) ◽  
pp. 21-41 ◽  
Author(s):  
R M Bielby ◽  
J P Stott ◽  
F Cullen ◽  
T M Tripp ◽  
J N Burchett ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Star Forming ◽  
The Galaxy ◽  
Circumgalactic Medium ◽  
Galaxy Environment ◽  
Using Data ◽  
Galaxy Population

ABSTRACT We present the first results from a study of O vi absorption around galaxies at z &lt; 1.44 using data from a near-infrared grism spectroscopic Hubble Space Telescope Large Programme, the Quasar Sightline and Galaxy Evolution (QSAGE) survey. QSAGE is the first grism galaxy survey to focus on the circumgalactic medium at z ∼ 1, providing a blind survey of the galaxy population. The galaxy sample is H α flux limited (f(H α) &gt; 2 × 10−17 erg s−1 cm−2) at 0.68 &lt; z &lt; 1.44, corresponding to ≳0.2–0.8 M⊙ yr−1. In this first of 12 fields, we combine the galaxy data with high-resolution STIS and COS spectroscopy of the background quasar to study O vi in the circumgalactic medium. At z ∼ 1, we find O vi absorption systems up to b ∼ 350 kpc (∼4Rvir) from the nearest detected galaxy. Further, we find ${\sim }50{{\ \rm per\ cent}}$ of ≳1 M⊙ yr−1 star-forming galaxies within 2Rvir show no associated O vi absorption to a limit of at least N(O vi) = 1013.9 cm−2. That we detect O vi at such large distances from galaxies and that a significant fraction of star-forming galaxies show no detectable O vi absorption disfavours outflows from ongoing star formation as the primary medium traced by these absorbers. Instead, by combining our own low- and high-redshift data with existing samples, we find tentative evidence for many strong (N(O vi) &gt; 1014 cm−2) O vi absorption systems to be associated with M⋆ ∼ 109.5–10 M⊙ mass galaxies (Mhalo ∼ 1011.5–12 M⊙ dark matter haloes), and infer that they may be tracing predominantly collisionally ionized gas within the haloes of such galaxies.

scholarly journals Molecular line ratio diagnostics along the radial cut and dusty ultraviolet-bright clumps in a spiral galaxy NGC 0628

2020 ◽  
Vol 495 (3) ◽  
pp. 2682-2712
Author(s):  
Selçuk Topal
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Line Ratio ◽  
H Ii Regions ◽  
Giant Molecular Clouds ◽  
Star Forming ◽  
The Galaxy ◽  
Star Formation In Galaxies ◽  
Molecular Lines ◽  
Co Gas

ABSTRACT Molecular emission lines are essential tools to shed light on many questions regarding star formation in galaxies. Multiple molecular lines are particularly useful to probe different phases of star-forming molecular clouds. In this study, we investigate the physical properties of giant molecular clouds (GMCs) using multiple lines of CO, i.e. CO(1–0, 2–1, 3–2) and 13CO(1–0), obtained at selected 20 positions in the disc of NGC 0628. A total of 11 positions were selected over the radial cut, including the centre, and remaining 9 positions were selected across the southern and northern arms of the galaxy. A total of 13 out of 20 positions are brighter at $24\, \mu {\rm m}$ and ultraviolet (UV) emission and hosting significantly more H ii regions compared to the rest of the positions indicating opposite characteristics. Our line ratio analysis shows that the gas gets warmer and thinner as a function of radius from the galaxy centre up to 1.7 kpc, and then the ratios start to fluctuate. Our empirical and model results suggest that the UV-bright positions have colder and thinner CO gas with higher hydrogen and CO column densities. However, the UV-dim positions have relatively warmer CO gas with lower densities bathed in GMCs surrounded by less number of H ii regions. Analysis of multiwavelength infrared and UV data indicates that the UV-bright positions have higher star formation efficiency than that of the UV-dim positions.

scholarly journals “E+A” Galaxies: Environment and Evolution

1999 ◽  
Vol 186 ◽  
pp. 125-131
Author(s):  
Ann I. Zabludoff
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Morphological Characteristics ◽  
Absorption Lines ◽  
Evolutionary Track ◽  
Star Forming ◽  
Blue Star ◽  
The Galaxy ◽  
Important Approach ◽  
Critical Link

One important approach to the study of galaxy evolution is to identify those galaxies whose spectral and/or morphological characteristics suggest that they are in transition. For example, “E+A” galaxies, which have strong Balmer absorption lines and no significant [OII] emission, are generally interpreted as post-starburst galaxies in which the star formation ceased within the last ~ Gyr (Fig. 1). This transition between a star forming and non-star forming state is a critical link in any galaxy evolution model in which a blue, star forming disk galaxy evolves into a SO or elliptical. Another possible evolutionary track is that the star formation in an “E+A” resumes at some later time, if enough gas remains in the galaxy after its starburst ends. Given this ambiguity, it is important to investigate (1) the environment's role in “E+A” evolution, (2) the stellar and gas morphologies of “E+A”s, (3) the likely progenitors of “E+A”s, and (4) how common the “E+A” phase is in the evolution of galaxies.

scholarly journals Local starbursts seen when the Universe was 2–4 Gyr old

2009 ◽  
Vol 5 (S266) ◽  
pp. 499-499
Author(s):  
S. M. Petty ◽  
D. F. de Mello ◽  
J. P. Gardner ◽  
J. S. Gallagher
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Rest Frame ◽  
Formation Rate ◽  
Starburst Galaxies ◽  
Spectral Energy ◽  
Multiple Star ◽  
Star Forming ◽  
The Galaxy ◽  
The Universe

AbstractWe explore the multiwavelength properties of three nearby starburst galaxies: NGC 3079, NGC 7673, and Mrk 08. We established that each of these galaxies has similar rest-frame far-ultraviolet (FUV) morphologies as Lyman-break galaxies (LBGs) at z ~ 1.5 and 4, when the age of the Universe was ~ 4.3 and ~ 1.6 Gyr, respectively. LBGs are at an important stage in galaxy evolution when the Universe had a peak in the star-formation-rate density. Many LBGs are primarily composed of star-forming clumps, i.e., stellar clusters, with a significant lack of older stellar populations. Here, we present the comparison of the spectral-energy distributions (SEDs) of three nearby starburst galaxies with those of typical LBGs. From our nearby sample, each object has been artificially redshifted to observe what the galaxies would look like at z ~ 1 to 4 in the rest-frame FUV. NGC 3079 is an edge-on Seyfert 2 galaxy. It has a bright bulge and is interacting with two other galaxies, with extended Hi only along NGC 3079. The redshifting process changes its appearance, so that at high z it looks like a chain galaxy with multiple knots of star formation and no bulge. NGC 7673 has extended Hi and the star formation is mostly within the inner optical region in the multiple star-forming clumps defining the galaxy morphology. In the FUV, the galaxy looks highly compact with little detail resolved. As it is artificially redshifted, the galaxy continues to look more spherical. Mrk 8 is a merging pair, with the two galaxies observable in the visible spectrum. It is classified as a Wolf–Rayet galaxy, which suggests a very young burst, and is composed of several large star-forming regions. The FUV image does not resolve the separate galaxies, and the appearance remains similar for each redshift. We use the Gini coefficient, M20, and the Sérsic index to quantify the morphologies. The SEDs of the objects have similarities with LBG stellar population models. Because these local galaxies can be studied in more detail, they act as a bridge between nearby observations of starburst galaxies and high-z starburst galaxies such as LBGs.

scholarly journals Ejective and preventative: the IllustrisTNG black hole feedback and its effects on the thermodynamics of the gas within and around galaxies

2020 ◽  
Vol 499 (1) ◽  
pp. 768-792 ◽  
Author(s):  
Elad Zinger ◽  
Annalisa Pillepich ◽  
Dylan Nelson ◽  
Rainer Weinberger ◽  
Rüdiger Pakmor ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Gas Cooling ◽  
Galaxy Population ◽  
Gas Accretion ◽  
Stellar Masses ◽  
Low Entropy

ABSTRACT Supermassive black holes (SMBHs) that reside at the centres of galaxies can inject vast amounts of energy into the surrounding gas and are thought to be a viable mechanism to quench star formation in massive galaxies. Here, we study the $10^{9-12.5}\, \mathrm{M_\odot }$ stellar mass central galaxy population of the IllustrisTNG simulation, specifically the TNG100 and TNG300 volumes at z = 0, and show how the three components – SMBH, galaxy, and circumgalactic medium (CGM) – are interconnected in their evolution. We find that gas entropy is a sensitive diagnostic of feedback injection. In particular, we demonstrate how the onset of the low-accretion black hole (BH) feedback mode, realized in the IllustrisTNG model as a kinetic, BH-driven wind, leads not only to star formation quenching at stellar masses $\gtrsim 10^{10.5}\, \mathrm{M_\odot }$ but also to a change in thermodynamic properties of the (non-star-forming) gas, both within the galaxy and beyond. The IllustrisTNG kinetic feedback from SMBHs increases the average gas entropy, within the galaxy and in the CGM, lengthening typical gas cooling times from $10\!-\!100\, \mathrm{Myr}$ to $1\!-\!10\, \mathrm{Gyr}$, effectively ceasing ongoing star formation and inhibiting radiative cooling and future gas accretion. In practice, the same active galactic nucleus (AGN) feedback channel is simultaneously ‘ejective’ and ‘preventative’ and leaves an imprint on the temperature, density, entropy, and cooling times also in the outer reaches of the gas halo, up to distances of several hundred kiloparsecs. In the IllustrisTNG model, a long-lasting quenching state can occur for a heterogeneous CGM, whereby the hot and dilute CGM gas of quiescent galaxies contains regions of low-entropy gas with short cooling times.

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