scholarly journals SFR Relation with Galaxy Environment and Colour at z between 0.03 and 0.1

2006 ◽  
Vol 2 (S235) ◽  
pp. 234-235
Author(s):  
Premana W. Premadi ◽  
A. Sitti Maryam
Keyword(s):  
Galaxy Evolution ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Limited Sample ◽  
Data Set ◽  
Star Forming ◽  
Diagnostic Diagram ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Environment

This work is a preliminary result of our attempt to examine the use of SFR in the study of galaxy evolution. For this purpose we use the Sloan Digital Sky Survey Data Release 2 (SDSS DR2) Abazajian et al. (2004) and the SFR Catalogue generated from this data set by Brinchmann et al. (2004) and Kaufmann et al. (2003). Following Kewley et al. (2001) we use the Diagnostic Diagram, log ([OIII]/Hβ) vs log ([NII]/Hα), to separate the star forming galaxies from other emission lines sources such as AGN. Choosing only those with S/N > 3 out of the Brinchmann et al. (2004) catalogue, we arrive at about 200 thousand galaxies as our starting SFR subsample. With 0.05 < z < 0.22 and limit at r = 17.77, the subsample can be used to reconstruct the properties of a volume limited sample of galaxies with M* = 6 1010Modot. We benefit from the fact that Brinchmann et al. (2004) SFR Catalogue has already been aperture-corrected using the likelihood distribution P(SFR/Li/colour) scheme. For the environment, we use the data generated by Kaufmann et al. (2003), and arrive at about 40 thousand target galaxies. In this work the environment is characterised by the number (N=0-30) of neighbouring galaxies within a projected radius of 2 Mpc and velocity di.erence of 500km/s from each target galaxy, and the magnitude limit is 14.5 < r < 17.77.

scholarly journals Influences of Galaxy Interactions on AGN Activity

2013 ◽  
Vol 30 ◽  
Author(s):  
Xin-Fa Deng ◽  
Guisheng Yu ◽  
Peng Jiang
Keyword(s):  
Survey Data ◽  
Strong Evidence ◽  
Sloan Digital Sky Survey ◽  
Limited Sample ◽  
Galaxy Interactions ◽  
Opposite Trend ◽  
Main Galaxy ◽  
Isolated Galaxies ◽  
Sky Survey ◽  
Data Release

AbstractUsing two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 7 , we explore influences of galaxy interactions on AGN activity. It is found that in the faint volume-limited sample, paired galaxies have a slightly higher AGN fraction than isolated galaxies, whereas in the luminous volume-limited sample, an opposite trend can be observed. The significance is <1σ. Thus, we do not observe strong evidence that interactions or mergers likely trigger the AGN activity.

scholarly journals The frequency of gaseous debris discs around white dwarfs

2020 ◽  
Vol 493 (2) ◽  
pp. 2127-2139 ◽  
Author(s):  
Christopher J Manser ◽  
Boris T Gänsicke ◽  
Nicola Pietro Gentile Fusillo ◽  
Richard Ashley ◽  
Elmé Breedt ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Signal To Noise Ratio ◽  
Infrared Emission ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Occurrence Rate ◽  
Limited Sample ◽  
Sky Survey ◽  
Gaseous Disc

ABSTRACT A total of 1–3 per cent of white dwarfs are orbited by planetary dusty debris detectable as infrared emission in excess above the white dwarf flux. In a rare subset of these systems, a gaseous disc component is also detected via emission lines of the Ca ii 8600 Å triplet, broadened by the Keplerian velocity of the disc. We present the first statistical study of the fraction of debris discs containing detectable amounts of gas in emission at white dwarfs within a magnitude and signal-to-noise ratio limited sample. We select 7705 single white dwarfs spectroscopically observed by the Sloan Digital Sky Survey (SDSS) and Gaia with magnitudes g ≤ 19. We identify five gaseous disc hosts, all of which have been previously discovered. We calculate the occurrence rate of a white dwarf hosting a debris disc detectable via Ca ii emission lines as $0.067\, \pm \, ^{0.042}_{0.025}$ per cent. This corresponds to an occurrence rate for a dusty debris disc to have an observable gaseous component in emission as 4 ± $_{2}^{4}$ per cent. Given that variability is a common feature of the emission profiles of gaseous debris discs, and the recent detection of a planetesimal orbiting within the disc of SDSS J122859.93+104032.9, we propose that gaseous components are tracers for the presence of planetesimals embedded in the discs and outline a qualitative model. We also present spectroscopy of the Ca ii triplet 8600 Å region for 20 white dwarfs hosting dusty debris discs in an attempt to identify gaseous emission. We do not detect any gaseous components in these 20 systems, consistent with the occurrence rate that we calculated.

scholarly journals Effect of bars on evolution of SDSS spiral galaxies

2020 ◽  
Vol 494 (4) ◽  
pp. 5839-5850
Author(s):  
Minbae Kim ◽  
Yun-Young Choi ◽  
Sungsoo S Kim
Keyword(s):  
Galaxy Evolution ◽  
Velocity Dispersion ◽  
Sufficient Conditions ◽  
Central Star ◽  
Sloan Digital Sky Survey ◽  
Causal Connection ◽  
Limited Sample ◽  
Massive Black Hole ◽  
Barred Galaxies ◽  
Sky Survey

ABSTRACT We explore the significance of bars in triggering central star formation (SF) and active galactic nucleus (AGN) activity for spiral galaxy evolution using a volume-limited sample with 0.020 &lt; z &lt; 0.055, Mr &lt; −19.5, and σ &gt; 70 km s−1 selected from Sloan Digital Sky Survey Data Release 7. On a central SF rate–σ plane, we measure the fraction of galaxies with strong bars in our sample and also the AGN fractions for barred and non-barred galaxies, respectively. The comparison between the bar and AGN fractions reveals a causal connection between the two phenomena of SF quenching and AGN activity. A massive black hole and abundant gas fuels are sufficient conditions to trigger AGNs. We infer that the AGNs triggered by satisfying the two conditions drive the strong AGN feedback, suddenly suppressing the central SF and leaving the SF sequence. We find that in galaxies where either of the two conditions is not sufficient, bars are a great help for the AGN triggering, accelerating the entire process of evolution, which is particularly evident in pseudo-bulge galaxies. All of our findings are obtained only when plotted in terms of their central velocity dispersion and central SFR (not galactic scale SFR), indicating that the AGN-driven SF quenching is confined in the central kpc region.

scholarly journals Stellar velocity dispersions and emission line properties of SDSS-III/BOSS galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 129-132
Author(s):  
D. Thomas ◽  
O. Steele ◽  
C. Maraston ◽  
J. Johansson ◽  
A. Beifiori ◽  
...  
Keyword(s):  
Emission Line ◽  
Velocity Dispersion ◽  
Target Selection ◽  
Emission Lines ◽  
Clear Correlation ◽  
Data Set ◽  
Star Forming ◽  
Public Data ◽  
Data Release ◽  
Stellar Velocity

AbstractWe perform a spectroscopic analysis of 492,450 galaxy spectra from the first two years of observations of the Sloan Digital Sky Survey-III/Baryonic Oscillation Spectroscopic Survey (BOSS) collaboration. This data set has been released in the ninth SDSS data release, the first public data release of BOSS spectra. We show that the typical signal-to-noise ratio of BOSS spectra is sufficient to measure stellar velocity dispersion and emission line fluxes for individual objects. The typical velocity dispersion of a BOSS galaxy is 240 km/s, with an accuracy of better than 30 per cent for 93 per cent of BOSS galaxies. The distribution in velocity dispersion is redshift independent between redshifts 0.15 and 0.7, which reflects the survey design targeting massive galaxies with an approximately uniform mass distribution in this redshift interval. The majority of BOSS galaxies lack detectable emission lines. We analyse the emission line properties and present diagnostic diagrams using the emission lines [OII], Hβ, [OIII], Halpha, and [NII] (detected in about 4 per cent of the galaxies). We show that the emission line properties are strongly redshift dependent and that there is a clear correlation between observed frame colours and emission line properties. Within in the low-z sample around 0.15 < z < 0.3, half of the emission-line galaxies have LINER-like emission line ratios, followed by Seyfert-AGN dominated spectra, and only a small fraction of a few per cent are purely star forming galaxies. AGN and LINER-like objects, instead, are less prevalent in the high-z sample around 0.4 < z < 0.7, where more than half of the emission line objects are star forming. This is a pure selection effect caused by the non-detection of weak Hβ emission lines in the BOSS spectra. Finally, we show that star forming, AGN and emission line free galaxies are well separated in the g - r vs r - i target selection diagram.

scholarly journals The Chemical Enrichment and Mass Assembly Histories of SDSS Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 307-307
Author(s):  
R. Cid Fernandes ◽  
N. V. Asari ◽  
J. P. Torres-Papaqui ◽  
W. Schoenell ◽  
L. Sodré ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Synthesis Method ◽  
Sloan Digital Sky Survey ◽  
Population Synthesis ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Sky Survey ◽  
Wide Range ◽  
Mass Assembly ◽  
Evolution Systems

AbstractWe explore the mass-assembly and chemical enrichment histories of star forming galaxies by applying a population synthesis method to a sample of nearly 70k galaxies culled from over 500k galaxies from the Sloan Digital Sky Survey Data Release 5. Our method decomposes the entire observed spectrum in terms of a sum of simple stellar populations spanning a wide range of ages and metallicities, thus allowing the reconstruction of galaxy histories. A comparative study of galaxy evolution is presented, where galaxies are grouped onto bins of nebular abundances or mass. We find that galaxies whose warm interstellar medium is poor in heavy elements are slow in forming stars. Their stellar metallicities also rise slowly with time, reaching their current values (Z⋆ ~ 1/4Z⊙) in the last ~100 Myr of evolution. Systems with metal rich nebulae, on the other hand, assembled most of their mass and completed their chemical evolution long ago, reaching Z⋆ ~ Z⊙ already at lookback times of a few Gyr. These same trends, which are ultimately a consequence of galaxy downsizing, appear when galaxies are grouped according to their stellar mass. The reconstruction of galaxy histories to this level of detail out of integrated spectra offers promising prospects in the field of galaxy evolution theories.

scholarly journals Nuclear starburst activity induced by elongated bulges in spiral galaxies

2018 ◽  
Vol 479 (1) ◽  
pp. 562-569 ◽  
Author(s):  
Eunbin Kim ◽  
Sungsoo S Kim ◽  
Yun-Young Choi ◽  
Gwang-Ho Lee ◽  
Richard de Grijs ◽  
...  
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Sloan Digital Sky Survey ◽  
Two Dimensional ◽  
Limited Sample ◽  
Barred Galaxies ◽  
Star Formation Activity ◽  
Sky Survey ◽  
Data Release ◽  
Environmental Dependence

ABSTRACT We study the effects of bulge elongation on the star formation activity in the centres of spiral galaxies using the data from the Sloan Digital Sky Survey Data Release 7. We construct a volume-limited sample of face-on spiral galaxies with Mr &lt; −19.5 mag at 0.02 ≤ $z$ &lt; 0.055 by excluding barred galaxies, where the aperture of the SDSS spectroscopic fibre covers the bulges of the galaxies. We adopt the ellipticity of bulges measured by Simard et al., who performed two-dimensional bulge + disc decompositions using the SDSS images of galaxies, and identify nuclear starbursts using the fibre specific star formation rates derived from the SDSS spectra. We find a statistically significant correlation between bulge elongation and nuclear starbursts in the sense that the fraction of nuclear starbursts increases with bulge elongation. This correlation is more prominent for fainter and redder galaxies, which exhibit higher ratios of elongated bulges. We find no significant environmental dependence of the correlation between bulge elongation and nuclear starbursts. These results suggest that non-axisymmetric bulges can efficiently feed the gas into the centre of galaxies to trigger nuclear starburst activity.

scholarly journals Low-redshift lowest-metallicity star-forming galaxies in the SDSS DR14

2019 ◽  
Vol 623 ◽  
pp. A40 ◽  
Author(s):  
Y. I. Izotov ◽  
N. G. Guseva ◽  
K. J. Fricke ◽  
C. Henkel
Keyword(s):  
Accurate Determination ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Strong Line ◽  
Star Forming ◽  
Line Method ◽  
Sky Survey ◽  
Low Metallicity ◽  
Semi Empirical

We present a sample of low-redshift (z <  0.133) candidates for extremely low-metallicity star-forming galaxies with oxygen abundances 12 + log O/H <  7.4 selected from the Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS). Three methods are used to derive their oxygen abundances. Among these methods two are based on strong [O II]λ3727 Å, [O III]λ4959 Å, and [O III]λ5007 Å emission lines, which we call strong-line and semi-empirical methods. These were applied for all galaxies. We have developed one of these methods, the strong-line method, in this paper. This method is specifically focused on the accurate determination of metallicity in extremely low-metallicity galaxies and may not be used at higher metallicities with 12 + log O/H ≳ 7.5. The third, the direct Te method, was applied for galaxies with detected [O III]λ4363 emission lines. All three methods give consistent abundances and can be used in combination or separately for selection of lowest-metallicity candidates. However, the strong-line method is preferable for spectra with a poorly detected or undetected [O III]λ4363 emission line. In total, our list of selected candidates for extremely low-metallicity galaxies includes 66 objects.

Outflows & Feedback from Extremely Red Quasars

2020 ◽  
Vol 15 (S359) ◽  
pp. 232-237
Author(s):  
Fred Hamann ◽  
Serena Perrotta ◽  
Nadia Zakamska
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Host Galaxies ◽  
Broad Absorption ◽  
Feedback Effects ◽  
Broad Emission ◽  
Sky Survey ◽  
High Incidence

AbstractFeedback from accreting supermassive black holes is often invoked in galaxy evolution models to inhibit star formation, truncate galaxy growth, and establish the observed black-hole/bulge mass correlation. We are studying outflows and feedback in a unique sample of extremely red quasars (ERQs) during the peak epoch of galaxy formation (at redshifts 2.3 < z < 3.4). We identified ERQs in the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey (BOSS) quasar catalog based on their extremely red i–W3 colors, but we find that ERQs typically have a suite of other extreme properties including 1) a high incidence of blueshifted broad absorption lines, 2) broad emission lines with unusually large rest equivalent widths (REWs), peculiar “wingless” profiles, and frequent large blueshifts (reaching ˜8740 km s-1), and 3) characteristically very broad and blueshifted [OIII] 4959,5007Å lines that trace ionized outflows at speeds up to ˜6700 km s-1. We propose that these ERQs represent a young quasar population with powerful outflows on the precipice of causing important disruptive feedback effects in their host galaxies.

scholarly journals Star Forming Galaxies and AGN Hosts: The Seagull Wings

2006 ◽  
Vol 2 (S235) ◽  
pp. 334-334
Author(s):  
Grazyna Stasińska ◽  
Roberto Cid Fernandes ◽  
Abílio Mateus ◽  
Laerte Sodré ◽  
Natalia V. Asari
Keyword(s):  
Optical Spectra ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Normal Star ◽  
Diagnostic Diagram ◽  
Sky Survey ◽  
Dividing Line

AbstractUsing photoionization models applied to the data from the Sloan Digital Sky Survey (SDSS) we propose a physically motivated dividing line in the [OIII]/Hβ vs [NII]/Hα (BPT) diagram between normal star forming (NSF) galaxies and AGN hosts. We also propose a new diagnostic diagram which can be used for optical spectra of galaxies with redshifts up to z= 1.3.

Detecting Gas Outflows in Type-2 AGNs Selected from the Sloan Digital Sky Survey

2012 ◽  
Vol 8 (S292) ◽  
pp. 372-372
Author(s):  
Hyun-Jin Bae ◽  
Jong-Hak Woo ◽  
Semyeong Oh
Keyword(s):  
Galaxy Evolution ◽  
Critical Role ◽  
Sloan Digital Sky Survey ◽  
Host Galaxies ◽  
Star Forming ◽  
Line Region ◽  
Systemic Velocity ◽  
Stellar Component ◽  
Sky Survey

AbstractEnergetic outflow from active galactic nuclei (AGNs) may play a critical role in galaxy evolution (e.g., Silk & Rees 1998). We present a velocity diagnostic for detecting gas outflow in the narrow-line region of Type-2 AGNs using line-of-sight velocity offsets of the [O iii] λ5007 and Hα emission lines with respect to the systemic velocity of stars in host galaxies (See Figure 1). We apply the diagnostics to nearby galaxies at 0.02 < z < 0.05, 3775 AGN-host and 907 star-forming galaxies as a comparison sample, which are selected from the Sloan Digital Sky Survey DR7. After obtaining a best-fit stellar population model for the continuum and a systemic velocity based on stellar lines, we subtract the stellar component to measure velocity offsets of each emission line. We find a sample of 169 AGN-host galaxies with outflow signatures, displaying a larger velocity shift of [O iii] than that of Hα, as expected in a decelerating outflow model (Komossa et al. 2008). We find that the offset velocity of [O iii] increases with Eddington ratio, suggesting that gas outflow depends on the energetics of AGN.

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