scholarly journals Quantifying correlations between galaxy emission lines and stellar continua using a PCA-based technique

2014 ◽  
Vol 10 (S306) ◽  
pp. 301-303
Author(s):  
Róbert Beck ◽  
László Dobos ◽  
István Csabai
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Active Galaxies ◽  
Emission Lines ◽  
Theoretical Modelling ◽  
Support Vector ◽  
Population Synthesis ◽  
Star Forming ◽  
Stellar Population Synthesis ◽  
Empirical Curve

AbstractWe analyse the correlations between continuum properties and emission line equivalent widths of star-forming and narrow-line active galaxies from SDSS. We show that emission line strengths can be predicted reasonably well from PCA coefficients of the stellar continuum using local multiple linear regression. Since upcoming sky surveys will make broadband observations only, theoretical modelling of spectra will be essential to estimate physical properties of galaxies. Combined with stellar population synthesis models, our technique will help generate more accurate model spectra and mock catalogues of galaxies to be used to fit data from new surveys. We also show that, by combining PCA coefficients from the pure continuum and the emission lines, a plausible distinction can be made between weak AGNs and quiescent star-forming galaxies. Our method uses a support vector machine, and allows a more refined separation of active and star-forming galaxies than the empirical curve of Kauffmann et al. (2003).

scholarly journals Determining star-formation rates in Active Galactic Nuclei hosts via stellar population synthesis

2020 ◽  
Author(s):  
Rogério Riffel ◽  
Nicolas D Mallmann ◽  
Gabriele S Ilha ◽  
Thaisa Storchi-Bergmann ◽  
Rogemar A Riffel ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
Stellar Population ◽  
Control Sample ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Host Galaxy ◽  
Population Synthesis ◽  
Stellar Population Synthesis

Abstract The effect of active galactic nuclei (AGN) feedback on the host galaxy, and its role in quenching or enhancing star-formation, is still uncertain due to the fact that usual star-formation rate (SFR) indicators – emission-line luminosities based on the assumption of photoionisation by young stars – cannot be used for active galaxies as the ionising source is the AGN. We thus investigate the use of SFR derived from the stellar population and its relation with that derived from the gas for a sample of 170 AGN hosts and a matched control sample of 291 galaxies. We compare the values of SFR densities obtained via the Hα emission line ($\rm \Sigma SFR_{Gas}$) for regions ionised by hot stars according to diagnostic diagrams with those obtained from stellar population synthesis ($\rm \Sigma SFR_\star$) over the last 1 to 100 Myr. We find that the $\rm \Sigma SFR_\star$over the last 20 Myrs closely reproduces the $\rm \Sigma SFR_{Gas}$, although a better match is obtained via the transformation: $\mbox{log($ \rm \Sigma SFR_\star $)} = (0.872\pm 0.004)\mbox{log($\rm \Sigma SFR_{Gas}$)} -(0.075\pm 0.006)$ (or $\mbox{log($\rm \Sigma SFR_{Gas}$)} = (1.147\pm 0.005)\mbox{log($ \rm \Sigma SFR_\star $)} +(0.086\pm 0.080)$), which is valid for both AGN hosts and non-active galaxies. We also compare the reddening obtained via the gas Hα/Hβ ratio with that derived via the full spectral fitting in the stellar population synthesis. We find that the ratio between the gas and stellar extinction is in the range 2.64 ≤AVg/AV⋆ ≤ 2.85, in approximate agreement with previous results from the literature, obtained for smaller samples. We interpret the difference as being due to the fact that the reddening of the stars is dominated by that affecting the less obscured underlying older population, while the reddening of the gas is larger as it is associated to a younger stellar population buried deeper in the dust.

scholarly journals Stellar Population Synthesis of Star-forming Clumps in Galaxy Pairs and Non-interacting Spiral Galaxies

2018 ◽  
Vol 234 (2) ◽  
pp. 35 ◽  
Author(s):  
Javier Zaragoza-Cardiel ◽  
Beverly J. Smith ◽  
Margarita Rosado ◽  
John E. Beckman ◽  
Theodoros Bitsakis ◽  
...  
Keyword(s):  
Stellar Population ◽  
Spiral Galaxies ◽  
Population Synthesis ◽  
Star Forming ◽  
Stellar Population Synthesis

scholarly journals Synthetic high-resolution line spectra of star-forming galaxies below 1200 Å, based on FUSE spectral libraries of hot stars

2003 ◽  
Vol 212 ◽  
pp. 744-746
Author(s):  
Carmelle Robert ◽  
Anne Pellerin ◽  
Alessandra Aloisi ◽  
Claus Leitherer ◽  
Charles G. Hoopes ◽  
...  
Keyword(s):  
Stellar Population ◽  
Magellanic Clouds ◽  
Population Synthesis ◽  
Hot Stars ◽  
Star Forming ◽  
Synthetic Spectra ◽  
Stellar Population Synthesis ◽  
The Galaxy ◽  
Wind Profiles ◽  
Spectral Libraries

We have generated far-UV stellar libraries using spectra of hot stars in the Galaxy and the Large and Small Magellanic Clouds. These libraries were implemented into the stellar population synthesis codes starburst99 and lavalsb and used to compute synthetic spectra of star-forming galaxies. Model spectra for galaxies are presented and variations of the hot star photospheric and wind profiles are discussed. This poster summarizes the work of Robert et al. (2002).

scholarly journals Wolf–Rayet stars in the Antennae unveiled by MUSE

2020 ◽  
Vol 500 (2) ◽  
pp. 2076-2095
Author(s):  
V M A Gómez-González ◽  
Y D Mayya ◽  
J A Toalá ◽  
S J Arthur ◽  
J Zaragoza-Cardiel ◽  
...  
Keyword(s):  
Stellar Population ◽  
Young Star ◽  
Interacting Galaxies ◽  
Population Synthesis ◽  
Large Telescope ◽  
Single Star ◽  
Star Forming ◽  
Evolutionary Scenario ◽  
Very Large Telescope ◽  
Stellar Population Synthesis

ABSTRACT We present the analysis of archival Very Large Telescope (VLT) Multi-Unit Spectroscopic Explorer (MUSE) observations of the interacting galaxies NGC 4038/39 (a.k.a. the Antennae) at a distance of 18.1 Mpc. Up to 38 young star-forming complexes with evident contribution from Wolf–Rayet (WR) stars are unveiled. We use publicly available templates of Galactic WR stars in conjunction with available photometric extinction measurements to quantify and classify the WR population in each star-forming region, on the basis of its nearly Solar oxygen abundance. The total estimated number of WR stars in the Antennae is 4053 ± 84, of which there are 2021 ± 60 WNL and 2032 ± 59 WC-types. Our analysis suggests a global WC to WN-type ratio of 1.01 ± 0.04, which is consistent with the predictions of the single star evolutionary scenario in the most recent bpass stellar population synthesis models.

Optical long-slit spectroscopy in the cluster Abell S0805

2019 ◽  
Vol 488 (3) ◽  
pp. 3685-3715
Author(s):  
P C da Rocha-Poppe ◽  
V A Fernandes-Martin ◽  
M Faúndez-Abans ◽  
M de Oliveira-Abans ◽  
G A Silva ◽  
...  
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Spectral Synthesis ◽  
Emission Lines ◽  
Cluster Galaxy ◽  
Nuclear Activity ◽  
Star Forming ◽  
Line Region ◽  
Nitrogen Emission ◽  
First Time

ABSTRACT This contribution aims to study the nature (kinematic, nuclear activity, and stellar population) of a sample of 10 galaxies in the poor cluster Abell S0805. As no detailed optical spectroscopy for some members has been published yet, the selected sample makes this study ideal for investigating the properties of the following objects: ESO 104- G(002, 006, 007, 008, 009, 010, 013), Fairall 0187, and PGC (062384, 062391). Our main results were obtained after subtraction of the underlying stellar population with the spectral synthesis code starlight. The residual spectra reveal seven galaxies with only absorption lines [ESO 104- G(002, 007, 008, 009), Fairall 0187 and PGC (062384, 062391)], and three galaxies with emission lines [ESO 104- G(006, 010, 013)]. According to the boundaries in the diagnostic diagrams, the intensities of H α and the low-ionization lines ([N ii] λ6584 Å and [S ii] λλ6716,6731 Å) suggest the following results: (i) the brightest cluster galaxy (ESO 104- G006, an elliptical cD galaxy) shows low-ionization nuclear emission-line region (LINER)-like excitation, quite common in ‘cool core clusters’; (ii) the ESO 104- G010 (‘X-Galaxy’ or ‘Crystal Frog’) shows an excess of the nitrogen emission-line [N ii] λ6584 Å not yet reported. We also suggest this object as a LINER; (iii) the spiral ESO 104- G013 is a star-forming galaxy with typical emission lines. No obvious signs of interaction were observed in this study. The heliocentric velocities agree within 1σ with the most recent values. The stellar population, rotation curves, and velocity dispersions are also discussed for the first time for some objects.

Stellar Population Synthesis in AGN Host Galaxies

2001 ◽  
Vol 1 ◽  
pp. 145-152
Author(s):  
M. Joly ◽  
C. Boisson ◽  
J. Moultaka ◽  
D. Pelat
Keyword(s):  
Stellar Population ◽  
Population Synthesis ◽  
Host Galaxies ◽  
Stellar Population Synthesis

Dissecting quasars with the J-PAS narrow-band photometric survey

2019 ◽  
Vol 15 (S356) ◽  
pp. 12-16
Author(s):  
Silvia Bonoli ◽  
Giorgio Calderone ◽  
Raul Abramo ◽  
Jailson Alcaniz ◽  
Narciso Benitez ◽  
...  
Keyword(s):  
Emission Line ◽  
Wavelength Range ◽  
Software Package ◽  
Narrow Band ◽  
Active Galaxies ◽  
Emission Lines ◽  
Low Resolution ◽  
Strong Emission ◽  
Optical Wavelength ◽  
Quasar Spectra

AbstractThe J-PAS survey will soon start observing thousands of square degrees of the Northern Sky with its unique set of 56 narrow band filters covering the entire optical wavelength range, providing, effectively, a low resolution spectra for every object detected. Active galaxies and quasars, thanks to their strong emission lines, can be easily identified and characterized with J-PAS data. A variety of studies can be performed, from IFU-like analysis of local AGN, to clustering of high-z quasars. We also expect to be able to extract intrinsic physical quasar properties from the J-PAS pseudo-spectra, including continuum slope and emission line luminosities. Here we show the first attempts of using the QSFit software package to derive the properties for 22 quasars at 0.8 < z < 2 observed by the miniJPAS survey, the first deg2 of J-PAS data obtained with an interim camera. Results are compared with the ones obtained by applying the same software to SDSS quasar spectra.

scholarly journals Using stellar population studies to determine the progenitors of GRBs and SNe

2009 ◽  
Vol 5 (S262) ◽  
pp. 436-437
Author(s):  
Christina C. Thöne ◽  
Lise Christensen ◽  
Johan P. U. Fynbo
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Population Studies ◽  
Population Models ◽  
Host Galaxy ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions

AbstractWe present spatially resolved emission line studies of three nearby GRB and SN hosts with longslit and/or IFU observations. We compare the environment of the GRBs/SNe with those of other star-forming regions in the host galaxy and try to get informations on the progenitor from stellar population models and metallicities.

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