scholarly journals Star formation in low-redshift cluster dwarf galaxies

2020 ◽  
Vol 493 (4) ◽  
pp. 5625-5635
Author(s):  
Cody M Rude ◽  
Madina R Sultanova ◽  
Gihan L Ipita Kaduwa Gamage ◽  
Wayne A Barkhouse ◽  
Sandanuwan P Kalawila Vithanage
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Sloan Digital Sky Survey ◽  
Galaxy Interactions ◽  
Cluster Data ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Ram Pressure ◽  
Low Mass ◽  
Central Concentration

ABSTRACT Evolution of galaxies in dense environments can be affected by close encounters with neighbouring galaxies and interactions with the intracluster medium. Dwarf galaxies (dGs) are important as their low mass makes them more susceptible to these effects than giant systems. Combined luminosity functions (LFs) in the r and u band of 15 galaxy clusters were constructed using archival data from the Canada–France–Hawaii Telescope. LFs were measured as a function of clustercentric radius from stacked cluster data. Marginal evidence was found for an increase in the faint-end slope of the u-band LF relative to the r-band with increasing clustercentric radius. The dwarf-to-giant ratio (DGR) was found to increase toward the cluster outskirts, with the u-band DGR increasing faster with clustercentric radius compared to the r-band. The dG blue fraction was found to be ∼2 times larger than the giant galaxy blue fraction over all clustercentric distance (∼5σ level). The central concentration (C) was used as a proxy to distinguish nucleated versus non-nucleated dGs. The ratio of high-C to low-C dGs was found to be ∼2 times greater in the inner cluster region compared to the outskirts (2.8σ level). The faint-end slope of the r-band LF for the cluster outskirts (0.6 ≤ r/r200 < 1.0) is steeper than the Sloan Digital Sky Survey field LF, while the u-band LF is marginally steeper at the 2.5σ level. Decrease in the faint-end slope of the r- and u-band cluster LFs towards the cluster centre is consistent with quenching of star formation via ram pressure stripping and galaxy–galaxy interactions.

scholarly journals What is Important? Morphological Asymmetries are Useful Predictors of Star Formation Rates of Star-forming Galaxies in SDSS Stripe 82

2021 ◽  
Vol 923 (2) ◽  
pp. 205
Author(s):  
Hassen M. Yesuf ◽  
Luis C. Ho ◽  
S. M. Faber
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Imaging Data ◽  
Galaxy Interactions ◽  
Star Forming ◽  
Sky Survey ◽  
Structural Variables ◽  
Central Concentration

Abstract The morphology and structure of galaxies reflect their star formation and assembly histories. We use the framework of mutual information (MI) to quantify the interdependence among several structural variables and to rank them according to their relevance for predicting the specific star formation rate (SSFR) by comparing the MI of the predictor variables with the SSFR and penalizing variables that are redundant. We apply this framework to study ∼3700 face-on star-forming galaxies (SFGs) with varying degrees of bulge dominance and central concentration and with stellar mass M ⋆ ≈ 109 M ⊙−5 × 1011 M ⊙ at redshift z = 0.02–0.12. We use the Sloan Digital Sky Survey (SDSS) Stripe 82 deep i-band imaging data, which improve measurements of asymmetry and bulge dominance indicators. We find that star-forming galaxies are a multiparameter family. In addition to M ⋆, asymmetry emerges as the most powerful predictor of SSFR residuals of SFGs, followed by bulge prominence/concentration. Star-forming galaxies with higher asymmetry and stronger bulges have higher SSFR at a given M ⋆. The asymmetry reflects both irregular spiral arms and lopsidedness in seemingly isolated SFGs and structural perturbations by galaxy interactions or mergers.

Further Investigation of the Effect of Galaxy Interactions on Star Formation

2013 ◽  
Vol 22 (2) ◽  
Author(s):  
Xin-Fa Deng ◽  
Fuyang Zhang
Keyword(s):  
Star Formation ◽  
Survey Data ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Apparent Magnitude ◽  
Galaxy Interactions ◽  
Main Galaxy ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample

AbstractFrom the apparent magnitude-limited the Main galaxy sample of the Sloan Digital Sky Survey Data Release 7, we construct a paired galaxy sample and a control sample without close companions with the projected separations

scholarly journals Galaxy pairs in the Sloan Digital Sky Survey – X. Does gas content alter star formation rate enhancement in galaxy interactions?

2015 ◽  
Vol 449 (4) ◽  
pp. 3719-3740 ◽  
Author(s):  
Jillian M. Scudder ◽  
Sara L. Ellison ◽  
Emmanuel Momjian ◽  
Jessica L. Rosenberg ◽  
Paul Torrey ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Gas Content ◽  
Galaxy Interactions ◽  
Rate Enhancement ◽  
Sky Survey

Outlying Hα blobs in SDSS IV MaNGA

2018 ◽  
Vol 14 (S344) ◽  
pp. 265-266
Author(s):  
Omkar Bait ◽  
Yogesh Wadadekar ◽  
Sudhanshu Barway
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Continuum Emission ◽  
Host Galaxy ◽  
Deep Imaging ◽  
Sky Survey ◽  
Optical Continuum ◽  
Low Mass ◽  
Field Unit ◽  
Rule Out

AbstractWe have discovered a population of 29 outlying Hα emitters which appear like unresolved blobs in the DR14 data release of the SDSS IV MaNGA integral field unit survey. They do not have any underlying optical continuum emission in deep imaging from the DECam Legacy Survey or Beijing-Arizona Sky Survey. These blobs either lie away from the disc of the host galaxy in the MaNGA IFU and/or have velocities which are different from the velocity map of the host galaxy. Interestingly, all of them show photoionisation due to star formation. These galaxies have very high specific star formation rates compared to the known population of dwarf galaxies. However, their metallicities are consistent with or even lowerthan those of the local volume dwarfs. Thus, we can possibly rule out tidal dwarf galaxies. They could represent a new population of low mass and starbursting dwarf galaxies.

scholarly journals Virgo Cluster Early?Type Dwarf Galaxies with the Sloan Digital Sky Survey. II. Early?Type Dwarfs with Central Star Formation

2006 ◽  
Vol 132 (6) ◽  
pp. 2432-2452 ◽  
Author(s):  
Thorsten Lisker ◽  
Katharina Glatt ◽  
Pieter Westera ◽  
Eva K. Grebel
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Central Star ◽  
Virgo Cluster ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Sky Survey

scholarly journals Active Galactic Nuclei Abundance in Cosmic Voids

2021 ◽  
Vol 922 (1) ◽  
pp. L17
Author(s):  
Hora D. Mishra ◽  
Xinyu Dai ◽  
Eduardo Guerras
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Void Size ◽  
Galaxy Interactions ◽  
Sky Survey ◽  
Void Galaxies ◽  
Ram Pressure ◽  
Cosmic Voids ◽  
Environmental Dependence

Abstract The abundance of active galactic nuclei (AGN) in cosmic voids is relatively unexplored in the literature, but can potentially provide new constraints on the environmental dependence of AGN activity and the AGN-host coevolution. We investigated AGN fractions in one of the largest samples of optically selected cosmic voids from Sloan Digital Sky Survey Data Release 12 for redshift range 0.2–0.7 for moderately bright and bright AGN. We separated inner and outer void regions based on the void size, given by its effective void radius. We classified galaxies at a distance <0.6 R eff as inner void members and galaxies in the interval 0.6 < R/R eff < 1.3 as outer void galaxies. We found higher average fractions in the inner voids (4.9 ± 0.7)% than for their outer counterparts (3.1 ± 0.1)% at z > 0.42, which clearly indicates an environmental dependence. This conclusion was confirmed upon further separating the data in narrower void-centric distance bins and measured a significant decrease in AGN activity from inner to outer voids for z > 0.42. At low redshifts (z < 0.42), we find very weak dependence on the environment for the inner and outer regions for two out of three bins. We argue that the higher fraction in low-density regions close to void centers relative to their outer counterparts observed in the two higher-redshift bins suggests that more efficient galaxy interactions may occur at a one-to-one level in voids that may be suppressed in denser environments due to higher velocity dispersions. It could also indicate less prominent ram pressure stripping in voids or some intrinsic host or void environment properties.

A comparison of the star formation rate and the specific star formation rate distributions between paired galaxies and isolated ones

2013 ◽  
Vol 91 (4) ◽  
pp. 337-342
Author(s):  
Xin-Fa Deng
Keyword(s):  
Star Formation ◽  
Comparative Studies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Galaxy Interactions ◽  
Isolated Galaxies ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample

From each of two volume-limited main galaxy samples of the Sloan Digital Sky Survey data release 7, a paired galaxy sample and an isolated galaxy sample are constructed and comparative studies between the star formation of galaxies in pairs and isolated are performed to explore influences of galaxy interactions on star formation. It is found that isolated galaxies have an enhancement of the star formation rate and the specific star formation rate, which suggests that interactions between galaxies are not the trigger of enhanced star formation.

Isolated groups of extremely blue dwarf galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 168-169
Author(s):  
Vitor Bootz ◽  
Marina Trevisan ◽  
Trinh Thuan ◽  
Yuri Izotov ◽  
Angela Krabbe ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Statistical Tests ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Tidal Forces ◽  
Star Formation Activity ◽  
Sky Survey ◽  
Blue Galaxies ◽  
Very High

AbstractInteractions and mergers between dwarf galaxies are mostly gas-rich and should be marked by an intense star formation activity. But these processes, which are expected to be common at earlier times, are very difficult to observe at low redshifts. To investigate that, we look in the Sloan Digital Sky Survey (SDSS) for compact groups that contain one luminous compact galaxy (LCG) with very high specific star formation rate (sSFR) and at least two other blue galaxies. We found 24 groups that satisfy these criteria, among which 12 groups have SDSS spectroscopic data for at least 2 member galaxies. Here we want to investigate, using the tidal strength estimator Q, how interactions between neighbouring galaxies affect the sSFR and concentration of each LCG. Statistical tests reveal a correlation between Q and their sSFR, indicating that tidal forces between neighbouring galaxies might be inducing bursts of star formation in the LCGs.

scholarly journals Broad line emission in dwarf galaxies: the first detection of low-metallicity AGN

2008 ◽  
Vol 4 (S255) ◽  
pp. 370-374
Author(s):  
Yuri I. Izotov
Keyword(s):  
Dwarf Galaxies ◽  
Line Emission ◽  
Sloan Digital Sky Survey ◽  
Strongly Correlated ◽  
Collisional Excitation ◽  
Sky Survey ◽  
Balmer Lines ◽  
Low Metallicity ◽  
Low Mass ◽  
High Metallicity

AbstractObservations of AGN show that they generally possess a high metallicity, varying from solar to supersolar metallicities. This is the case since AGN are usually found in massive, bulge-dominated galaxies that have converted most of their gas into stars by the present epoch. Since AGN metallicity is strongly correlated with stellar mass, low-metallicity AGN are expected to be in low-mass dwarf galaxies. However, until now, searches in low-mass galaxies have only turned up AGN with metallicities around half that of typical AGN, i.e. with solar or slightly subsolar values. We report the discovery of four low-metallicity dwarf galaxies in the Data Release 6 of the Sloan Digital Sky survey, with 12 + log O/H in the range 7.4–8.0, and that appear to harbor an AGN. In the course of a long-range program to search for extremely metal-deficient emission-line dwarf galaxies, we have come across four galaxies with very unusual spectra: the strong permitted emission lines, mainly the Hα line, show very prominent broad components, with full widths at zero intensity corresponding to velocities varying between 2200 and 3500 km s−1, and extraordinarily large broad Hα luminosities, varying from 3×1041 to 2×1042 erg s−1. The Balmer lines show a very steep decrement, suggesting collisional excitation and that the broad emission comes from very dense gas (Ne ≫ 104 cm−3). Only the presence of an accretion disk around an intermediate-mass black hole in the dwarf galaxies appears to account for these properties.

scholarly journals Are sdAs helium core stars?

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Ingrid Pelisoli ◽  
S. O. Kepler ◽  
Detlev Koester
Keyword(s):  
Main Sequence ◽  
Galactic Disk ◽  
Physical Nature ◽  
Sloan Digital Sky Survey ◽  
Distance Modulus ◽  
Main Sequence Stars ◽  
Sky Survey ◽  
Balmer Lines ◽  
Low Mass ◽  
Binary Evolution

AbstractEvolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

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