scholarly journals Star Formation Rate of the Low Redshift Dwarf Galaxies J080947.50+213717.2 and J151839.94+220514.4

2021 ◽  
Vol 7 (1) ◽  
pp. 18-24
Author(s):  
S. P. Gautam ◽  
A. Silwal ◽  
A. Sedain ◽  
B. Aryal
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Strong Emission ◽  
Star Forming ◽  
Normal Galaxies ◽  
Characteristic Lines ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We performed a spectroscopic analysis of two low redshift dwarf galaxies, SDSSJ080947.50+213717.2, and SDSSJ151839.94+220514.4 selected from a catalogue of Paudel et al. 2018. The strong emission lines of the SDSS spectra of both galaxies were studied and the elements responsible were identified for those characteristic lines. The line ratio between Hα and Hβ (Hα/ Hβ) for the galaxies SDSSJ080947.50+213717.2 and SDSSJ151839.94+220514.4 was found to be 2.77 and 2.75, respectively, suggesting these are nearly dust free and star forming galaxies.. The star formation rate of the galaxies SDSSJ080947.50+213717.2 and SDSSJ151839.94+220514.4 was found to be 0.0232 M☉yr-1 and 0.05221 M☉yr-1, respectively. The ratio between NII and Hα was used to calculate the emission line metallicity, which was found to be 8.13 dex and 8.46 dex for the galaxies SDSSJ080947.50+213717.2 and SDSSJ151839.94+220514.4, respectively. From the comparison of our findings with the previous studies, slightly lower star formation rate than normal galaxies were noticed. The metallicity value for both of the galaxies were positioned in the group of low-surface-brightness galaxies of Bargvell's dwarfs..

Star formation in dwarf galaxies in the ELAIS N1 field

2018 ◽  
Vol 14 (S344) ◽  
pp. 292-295
Author(s):  
Tímea O. Kovács ◽  
Denis Burgarella ◽  
L. Viktor Tóth
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Normal Galaxies ◽  
Radiation Data ◽  
Order Of Magnitude ◽  
Stellar Masses

AbstractWe estimated several parameters of dwarf galaxies, including their star formation rate and dust mass, and compared them with galaxies with larger stellar masses.We have chosen dwarf galaxies in the ELAIS N1 field, and fitted their Spectral Energy Distributions (SED). We used data from the new Herschel SPIRE and PACS Point Source catalogues to constrain the infrared radiation. Data available in VIZIER from multiple surveys have also been used.We determined that the star formation rate (SFR), M* and Mdust is one order of magnitude lower in dwarf galaxies compared to galaxies with larger stellar masses. However, the starburtiness was higher in the dwarf galaxies. They also had lower redshifts than normal galaxies, so we compared them to a subsample of normal galaxies with lower redshifts. The dust masses and SFRs of the dwarf galaxies were slightly lower, but their starburtiness was higher.

scholarly journals Rejuvenation triggers nuclear activity in nearby galaxies

2021 ◽  
Author(s):  
Ignacio Martin Navarro ◽  
Francesco Shankar ◽  
Mar Mezcua
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Sudden Increase ◽  
Star Forming ◽  
Normal Galaxies ◽  
Gas Accretion

Abstract Galaxies, forming and evolving within their host dark matter haloes, are the end-product of a balance between gas cooling, star formation and feedback. Energy/Momentum feedback, in particular from active galactic nuclei (AGN), is believed to play a crucial role in the evolution of galaxies by gradually quenching their star formation. In the local Universe many galaxies with an AGN are indeed observed to reside in the so-called green valley, usually interpreted as a transition phase from a blue star formation epoch to a red quenched state. We use data from the Sloan Digital Sky Survey to show that such an interpretation requires substantial revision. Optically-selected nearby AGN galaxies follow exponentially declining star formation histories, as normal galaxies of similar stellar and dark matter halo mass, reaching in the recent past (~0.1 Gyr ago) star formation rate levels consistent with a quiescent population. However, we find that local AGN galaxies have experienced a sudden increase in their star formation rate, unfolding on timescales similar to those typical of AGN activity, suggesting that both star formation and AGN activity were triggered simultaneously. We find that this quenching process followed by an enhancement in the star formation rate is common to AGN galaxies and more pronounced in early type galaxies. Our results demonstrate that local AGN galaxies are not a transition type between star-forming and quiescent galaxies as previously postulated, but simply galaxies experiencing a recent gas accretion episode.

scholarly journals Properties of galaxies with an offset between the position angles of the major kinematic and photometric axes

2020 ◽  
Vol 634 ◽  
pp. A26 ◽  
Author(s):  
L. S. Pilyugin ◽  
E. K. Grebel ◽  
I. A. Zinchenko ◽  
J. M. Vílchez ◽  
F. Sakhibov ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Velocity Fields ◽  
Oxygen Abundance ◽  
Star Forming ◽  
Measured Position ◽  
Central Oxygen ◽  
Straight Lines

We derive the photometric, kinematic, and abundance characteristics of 18 star-forming MaNGA galaxies with fairly regular velocity fields and surface brightness distributions and with a large offset between the measured position angles of the major kinematic and photometric axes, ΔPA ≳ 20°. The aim is to examine if there is any other distinctive characteristic common to these galaxies. We found morphological signs of interaction in some (in 11 out of 18) but not in all galaxies. The observed velocity fields show a large variety; the maps of the isovelocities vary from an hourglass-like appearance to a set of straight lines. The position angles of the major kinematic axes of the stellar and gas rotations are close to each other. The values of the central oxygen abundance, radial abundance gradient, and star formation rate are distributed within the intervals defined by galaxies with small (no) ΔPA of similar mass. Thus, we do not find any specific characteristic common to all galaxies with large ΔPA. Instead, the properties of these galaxies are similar to those of galaxies with small (no) ΔPA. This suggests that either the reason responsible for the large ΔPA does not influence other characteristics or the galaxies with large ΔPA do not share a common origin, they can, instead, originate through different channels.

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.

scholarly journals The ionization parameter of star-forming galaxies evolves with the specific star formation rate

2018 ◽  
Vol 477 (4) ◽  
pp. 5568-5589 ◽  
Author(s):  
Melanie Kaasinen ◽  
Lisa Kewley ◽  
Fuyan Bian ◽  
Brent Groves ◽  
Daichi Kashino ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Ionization Parameter

scholarly journals THE STAR-FORMATION-RATE-DENSITY RELATION AT 0.6

2011 ◽  
Vol 735 (1) ◽  
pp. 53 ◽  
Author(s):  
Shannon G. Patel ◽  
Daniel D. Kelson ◽  
Bradford P. Holden ◽  
Marijn Franx ◽  
Garth D. Illingworth
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Density Relation

scholarly journals Far-Infrared Emission from Clumpy Irregular Galaxies

1987 ◽  
Vol 115 ◽  
pp. 647-647
Author(s):  
U. Klein ◽  
J. Heidmann ◽  
R. Wielebinski ◽  
E. Wunderlich
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Hubble Constant ◽  
Far Infrared ◽  
Hii Regions ◽  
Infrared Emission ◽  
Star Forming ◽  
Irregular Galaxies

The four clumpy irregular galaxies Mkr 8, 296,297 and 325 have been observed by IRAS. All galaxies have been detected in at least two of the four detector bands. The ratios of the 100 to 60-m flux densities are comparable to those of HII regions or violently star forming galaxies. The average star formation rate in clumpy irregular galaxies is of the order of a few solar masses per year (based on their average far-infrared luminosity and a Hubble constant of 75 km s−1 Mpc−1.

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 SDSS J114818.18-013823.7: Forming Compact Dwarf Galaxy through the Dwarf-Dwarf Merger

2021 ◽  
Vol 7 (2) ◽  
pp. 49-57
Author(s):  
D. N. Chhatkuli ◽  
S. Paudel ◽  
A. K. Gautam ◽  
B. Aryal
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Star Formation Rate ◽  
Dwarf Galaxy ◽  
Formation Rate ◽  
Absolute Magnitude ◽  
Spectroscopic Properties ◽  
Normal Galaxies ◽  
Star Formation Activity ◽  
The Galaxy

We studied the spectroscopic properties of the low redshift (z = 0.0130) interacting dwarf galaxy SDSS J114818.18-013823.7. It is a compact galaxy of half-light radius 521 parsec. It’s r-band absolute magnitude is -16.71 mag. Using a publicly available optical spectrum from the Sloan Sky Survey data archive, we calculated star-formation rate, emission line metallicity, and dust extinction of the galaxy. Star formation rate (SFR) due to Hα is found to be 0.118 Mʘ year-1 after extinction correction. The emission-line metallicity, 12+log(O/H), is 8.13 dex. Placing these values in the scaling relation of normal galaxies, we find that SDSS J114818.18-013823.7 is a significant outlier from both size-magnitude relation and SFR-B-band absolute relation. Although SDSS J114818.18-013823.7 possess enhance rate of star-formation, the current star-formation activity can persist several Giga years in the future at the current place and it remains compact.

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