scholarly journals Calculation of velocity dispersion of the nearby galaxies using different stellar template libraries

2010 ◽  
pp. 57-69
Author(s):  
Ana Lalovic
Keyword(s):  
Reasonable Agreement ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Sloan Digital Sky Survey ◽  
Signal To Noise ◽  
Method Of Calculation ◽  
Sky Survey ◽  
Best Fitting ◽  
Nearby Galaxies ◽  
Spectral Libraries

We present the central velocity dispersion measurements of the nearby galaxies from the Sloan Digital Sky Survey (SDSS). Using the sample from the paper by Ho et al. 2009, we have selected 23 galaxies for which we calculate the velocity dispersion. We have used the Penalized Pixel-Fitting code (Cappellari and Emsellem2004) to measure the velocity dispersion throughout the four chosen spectral regions: (3800,4568)?A, (4568,5336)?A, (5336,6104) and (6104,6872)?A. In all these regions, we have separately calculated dispersions and corresponding errors. We found that the measured values may vary with the change of spectral region, but, if weighted properly with the measure of the goodness of the fit, the final results will be shifted coloser to those for the best fitting regions. We have also tested how the use of different spectral libraries (Miles, Valdes and Elodie databases) influences measurements and we showed that they do not affect measurements much. However, Elodie stellar library introduces the smallest errors in the velocity dispersion and it is the most stable throughout all four spectral regions. For these reasons it should be used preferentially when dealing with the SDSS spectra. We compare the results with the above mentioned paper and find a reasonable agreement. The agreement with the dispersions available in the HyperLeda database is very poor. The best agreement is obtained with SDSS measurements. We believe that our measurements are useful since SDSS velocity dispersions measurements are not available for many galaxies and the method of calculation of the velocity dispersion outlined in this work enables calculation of velocity dispersion for any galaxy. Of course, spectra with signal-to-noise ratio below 20 should be taken with caution.

scholarly journals The impact of disturbed galaxy clusters on the kinematics of active galactic nuclei

2020 ◽  
Vol 499 (3) ◽  
pp. 3792-3805
Author(s):  
Lawrence E Bilton ◽  
Kevin A Pimbblet ◽  
Yjan A Gordon
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Cluster Galaxies ◽  
Sky Survey ◽  
The Impact

ABSTRACT We produce a kinematic analysis of AGN-hosting cluster galaxies from a sample of 33 galaxy clusters selected using the X-ray Clusters Database (BAX) and populated with galaxies from the Sloan Digital Sky Survey Data Release 8. The 33 galaxy clusters are delimited by their relative intensity of member galaxy substructuring as a proxy to core merging to derive two smaller sub-samples of 8 dynamically active (merging) and 25 dynamically relaxed (non-merging) states. The AGN were selected for each cluster sub-sample by employing the WHAN diagram to the strict criteria of log10([N ii]/Hα) ≥ −0.32 and EWHα ≥ 6 Å, providing pools of 70 mergings and 225 non-merging AGN sub-populations. By co-adding the clusters to their respective dynamical states to improve the signal-to-noise ratio of our AGN sub-populations we find that merging galaxy clusters on average host kinematically active AGN between 0–1.5r200 as r200 → 0, where their velocity dispersion profile (VDP) presents a significant deviation from the non-AGN sub-population VDP by ≳3σ. This result is indicative that the AGN-hosting cluster galaxies have recently coalesced on to a common potential. Further analysis of the composite distributions illustrates non-merging AGN-hosting sub-populations have, on average, already been accreted and predominantly lie within backsplash regions of the projected phase-space. This suggests merging cluster dynamical states hold relatively younger AGN sub-populations kinematically compared with those found in non-merging cluster dynamical states.

scholarly journals Galaxy properties as revealed by MaNGA – III. Kinematic profiles and stellar population gradients in S0s

2020 ◽  
Vol 495 (3) ◽  
pp. 2894-2908 ◽  
Author(s):  
H Domínguez Sánchez ◽  
M Bernardi ◽  
F Nikakhtar ◽  
B Margalef-Bentabol ◽  
R K Sheth
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Elliptical Galaxies ◽  
Element Abundance ◽  
High Signal ◽  
Galactocentric Distance ◽  
Massive Galaxies ◽  
Nearby Galaxies ◽  
Mass Functions

ABSTRACT This is the third paper of a series where we study the stellar population gradients (SP; ages, metallicities, α-element abundance ratios, and stellar initial mass functions) of early-type galaxies (ETGs) at $z$ ≤ 0.08 from the Mapping Nearby Galaxies at APO Data Release 15 (MaNGA-DR15) survey. In this work, we focus on the S0 population and quantify how the SP varies across the population as well as with galactocentric distance. We do this by measuring Lick indices and comparing them to SP synthesis models. This requires spectra with high signal-to-noise ratio which we achieve by stacking in bins of luminosity (Lr) and central velocity dispersion (σ0). We find that: (1) there is a bimodality in the S0 population: S0s more massive than $3\times 10^{10}\, \mathrm{M}_\odot$ show stronger velocity dispersion and age gradients (age and σr decrease outwards) but little or no metallicity gradient, while the less massive ones present relatively flat age and velocity dispersion profiles, but a significant metallicity gradient (i.e. [M/H] decreases outwards). Above $2\times 10^{11}\, \mathrm{M}_\odot$, the number of S0s drops sharply. These two mass scales are also where global scaling relations of ETGs change slope. (2) S0s have steeper velocity dispersion profiles than fast-rotating elliptical galaxies (E-FRs) of the same luminosity and velocity dispersion. The kinematic profiles and SP gradients of E-FRs are both more similar to those of slow-rotating ellipticals (E-SRs) than to S0s, suggesting that E-FRs are not simply S0s viewed face-on. (3) At fixed σ0, more luminous S0s and E-FRs are younger, more metal rich and less α-enhanced. Evidently for these galaxies, the usual statement that ‘massive galaxies are older’ is not true if σ0 is held fixed.

scholarly journals Clustering and Halo Occupation Distribution of Active Galactic Nuclei

2013 ◽  
Vol 9 (S304) ◽  
pp. 243-243
Author(s):  
Takamitsu Miyaji ◽  
M. Krumpe ◽  
A. Coil ◽  
H. Aceves ◽  
B. Husemann
Keyword(s):  
Cross Correlation ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Bias Parameter ◽  
X Ray ◽  
Sky Survey ◽  
Galaxy Population ◽  
Halo Occupation Distribution

AbstractWe present the results of our series of studies on correlation function and halo occupation distribution of AGNs utilizing data the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we take cross-correlation approach, where cross-correlation functions (CCF) between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are analyzed using the Halo Occupation Distribution (HOD) model, where the CCFs are divided into the term contributed by the AGN-galaxy pairs that reside in one dark matter halo (DMH), (the 1-halo term) and those from two different DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter, which is a function of the typical mass of the DMHs in which AGNs reside. The combination of the 1-halo and 2-halo terms gives, not only the typical DMH mass, but also how the AGNs are distributed among the DMHs as a function of mass separately for those at the center of the DMHs and satellites. The main results are as follows: (1) the range of typical mass of the DMHs in various sub-samples of AGNs log (MDMH/h−1MΘ) ~ 12.4–13.4, (2) we found a dependence of the AGN bias parameter on the X-ray luminosity of AGNs, while the optical luminosity dependence is not significant probably due to smaller dynamic range in luminosity for the optically-selected sample, and (3) the growth of the number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or even may be flat, contrary to that of the galaxy population in general, which grows with MDMH proportionally, suggesting a suppression of AGN triggering in denser environment. In order to investigate the origin of the X-ray luminosity dependence, we are also investigating the dependence of clustering on the black hole mass and the Eddington ratio, we also present the results of this investigation.

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 Global analysis of luminosity- and colour-dependent galaxy clustering in the Sloan Digital Sky Survey

2019 ◽  
Vol 488 (1) ◽  
pp. 1220-1234
Author(s):  
Niladri Paul ◽  
Isha Pahwa ◽  
Aseem Paranjape
Keyword(s):  
Dynamic Range ◽  
Global Analysis ◽  
Spatial Separation ◽  
Sloan Digital Sky Survey ◽  
Independent Manner ◽  
Galaxy Clustering ◽  
Satellite Galaxy ◽  
Sky Survey ◽  
Best Fitting ◽  
Sphere Approximation

ABSTRACT We present a halo occupation distribution (HOD) analysis of the luminosity- and colour-dependent galaxy clustering in the Sloan Digital Sky Survey. A novelty of our technique is that it uses a combination of clustering measurements in luminosity bins to perform a global likelihood analysis, simultaneously constraining the HOD parameters for a range of luminosity thresholds. We present simple, smooth fitting functions which accurately describe the resulting luminosity dependence of the best-fitting HOD parameters. To minimize systematic halo modelling effects, we use theoretical halo 2-point correlation functions directly measured and tabulated from a suite of N-body simulations spanning a large enough dynamic range in halo mass and spatial separation. Thus, our modelling correctly accounts for non-linear and scale-dependent halo bias as well as any departure of halo profiles from universality, and we additionally account for halo exclusion using the hard sphere approximation. Using colour-dependent clustering information, we constrain the satellite galaxy red fraction in a model-independent manner which does not rely on any group-finding algorithm. We find that the resulting luminosity dependence of the satellite red fraction is significantly shallower than corresponding measurements from galaxy group catalogues, and we provide a simple fitting function to describe this dependence. Our fitting functions are readily usable in generating low-redshift mock galaxy catalogues, and we discuss some potentially interesting applications as well as possible extensions of our technique.

scholarly journals Characterisation of the continuum and kinematical properties of nearby NLS1

2019 ◽  
Vol 629 ◽  
pp. A50
Author(s):  
Gabriel A. Oio ◽  
Luis R. Vega ◽  
Eduardo O. Schmidt ◽  
Diego Ferreiro
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Velocity Dispersion ◽  
Spectral Synthesis ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Composite Spectra ◽  
Sky Survey ◽  
Stellar Velocity ◽  
Gaussian Decomposition

Aims. In order to study the slope and strength of the non-stellar continuum, we analysed a sample from nearby Narrow Line Seyfert 1 (NLS1). Also, we re-examined the location of NLS1 galaxies on the MBH − σ⋆ relation, using the stellar velocity dispersion and the [OIII]λ5007 emission line as a surrogate of the former. Methods. We studied spectra of a sample of 131 NLS1 galaxies taken from the Sloan Digital Sky Survey (SDSS) DR7. We approached determining the non-stellar continuum by employing the spectral synthesis technique, which uses the code STARLIGHT, and by adopting a power-law base to model the non-stellar continuum. Composite spectra of NLS1 galaxies were also obtained based on the sample. In addition, we obtained the stellar velocity dispersion from the code and by measuring Calcium II Triplet absorption lines and [OIII] emission lines. From Gaussian decomposition of the Hβ profile we calculated the black hole mass. Results. We obtained a median slope of β = −1.6 with a median fraction of contribution of the non-stellar continuum to the total flux of 0.64. We determined black hole masses in the range of log(MBH/M⊙) = 5.6–7.5, which is in agreement with previous works. We found a correlation between the luminosity of the broad component of Hβ and black hole mass with the fraction of a power-law component. Finally, according to our results, NLS1 galaxies in our sample are located mostly underneath the MBH − σ⋆ relation, both considering the stellar velocity dispersion (σ⋆) and the core component of [OIII]λ5007.

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 COLOR-MAGNITUDE DISTRIBUTION OF FACE-ON NEARBY GALAXIES IN SLOAN DIGITAL SKY SURVEY DR7

2014 ◽  
Vol 787 (1) ◽  
pp. 63 ◽  
Author(s):  
Shuo-Wen Jin ◽  
Qiusheng Gu ◽  
Song Huang ◽  
Yong Shi ◽  
Long-Long Feng
Keyword(s):  
Sloan Digital Sky Survey ◽  
Magnitude Distribution ◽  
Sky Survey ◽  
Nearby Galaxies

scholarly journals Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

2017 ◽  
Vol 154 (1) ◽  
pp. 28 ◽  
Author(s):  
Michael R. Blanton ◽  
Matthew A. Bershady ◽  
Bela Abolfathi ◽  
Franco D. Albareti ◽  
Carlos Allende Prieto ◽  
...  
Keyword(s):  
Milky Way ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Nearby Galaxies
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