scholarly journals Emission Line Properties of GPS/CSS Galaxies

2003 ◽  
Vol 20 (1) ◽  
pp. 147-150
Author(s):  
Anton M. Koekemoer ◽  
Christopher P. O'Dea ◽  
Stefi A. Baum
Keyword(s):  
Emission Line ◽  
Observational Data ◽  
Spectroscopic Data ◽  
Source Size ◽  
Emission Lines ◽  
Turnover Frequency ◽  
Intrinsic Properties ◽  
Excitation State ◽  
Compact Sources ◽  
Initial Results

AbstractWe present initial results from a program that we have begun, aimed at increasing the number of GPS and CSS sources for which good spectroscopic data are available for a variety of emission lines. We combine new observational data with previously published results to investigate whether there are any relationships between the excitation state of the gas and the radio properties of the sources, retaining distinctions between GPS and GSS galaxies and quasars. In scenarios where the youngest, most compact sources interact most strongly with the gas, it is perhaps to be expected that this can have an effect on the overall excitation state of the gas, which could therefore correlate with radio properties such as turnover frequency that plausibly trace the source size and age. However, we find a degree of scatter between the turnover frequency and gas excitation state that is several times larger than the characteristic degree of uncertainty in our line ratio measurements. This would suggest that either there is no underlying relationship between turnover frequency and excitation state, or alternatively that any potential relationship is completely diluted by variations in the intrinsic properties of the gas from one source to the next, which would thus be an important factor in determining the source properties.

scholarly journals Long Term UV Continuum and Line Variability in NGC 1275

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Bryan Rithesh Miranda ◽  
Vijayakumar H Doddamani ◽  
Vedavathi P
Keyword(s):  
Emission Line ◽  
Spectroscopic Data ◽  
Wavelength Region ◽  
Emission Lines ◽  
Observational Period ◽  
Flux Variability Analysis ◽  
Variability Analysis ◽  
Ngc 1275 ◽  
First Time

In this paper, we present our results for the first time on long term emission-line and continuum variability studies using the International Ultraviolet Explorer’s final archive of UV spectroscopic data obtained in the wavelength region from 1150 Å to 3200 Å for NGC 1275, a dust dominated BL Lac characterized by the Rmax and  F-variance parameter. The UV continuum flux variability analysis presented in this paper covers more number of emission-line free continuum windows in the UV region centred at  1710 Å, 1800 Å, 2625 Å, 2875 Å & 3025 Å. We have obtained a higher value of Fvar  ~ 45 % at 1710 Å and a lower value of ~ 30 % at 1800 Å for the IUE's observational period of 1978 - 1989. The Lyα, C IV, C III] and Mg II emission lines have been observed as weaker line features on fewer occasions intermittently.

scholarly journals Early Observations of the Interstellar Comet 2I/Borisov

Geosciences ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 519
Author(s):  
Chien-Hsiu Lee
Keyword(s):  
Solar System ◽  
Emission Line ◽  
Spectroscopic Data ◽  
Emission Lines ◽  
Short Tail ◽  
Upper Limit ◽  
Early Imaging

2I/Borisov is the second ever interstellar object (ISO). It is very different from the first ISO ’Oumuamua by showing cometary activities, and hence provides a unique opportunity to study comets that are formed around other stars. Here we present early imaging and spectroscopic follow-ups to study its properties, which reveal an (up to) 5.9 km comet with an extended coma and a short tail. Our spectroscopic data do not reveal any emission lines between 4000–9000 Angstrom; nevertheless, we are able to put an upper limit on the flux of the C2 emission line, suggesting modest cometary activities at early epochs. These properties are similar to comets in the solar system, and suggest that 2I/Borisov—while from another star—is not too different from its solar siblings.

scholarly journals Solar EUV Rocket Telescope and Spectrograph (SERTS) Observations of Fe XII Emission Lines

1996 ◽  
Vol 152 ◽  
pp. 531-536
Author(s):  
F.P. Keenan ◽  
R.J. Thomas ◽  
W.M. Neupert ◽  
V.J. Foster ◽  
C.J. Greer ◽  
...  
Keyword(s):  
Active Region ◽  
Emission Line ◽  
Electron Temperature ◽  
Observational Data ◽  
Electron Density ◽  
Wavelength Range ◽  
Solar Spectrum ◽  
Emission Lines ◽  
First Time ◽  
Good Agreement

Abstract.Theoretical electron density sensitive emission line ratios involving transitions in the 186–383 Å wavelength range are compared with observational data for a solar active region and a subflare, obtained by the Solar EUV Rocket Telescope and Spectrograph (SERTS). Electron densities derived from the majority of the ratios are consistent with one another, and are also in good agreement with the values of density estimated from diagnostic lines in other species formed at similar temperatures to Fe XII. These results provide observational support for the general accuracy of the diagnostic calculations. In addition, our analysis indicates that a line at 283.70 Å in the active region spectrum is the 3s23p32D3/2−3s3p42P1/2 transition in Fe XII, the first time (to the best of our knowledge) that this line has been identified in the solar spectrum. Several of the line ratios considered are predicted to be relatively insensitive to the adopted electron temperature and density, and the generally good agreement found between theory and observation for these provides evidence for the reliability of the SERTS instrument calibration. The application of the Fe XII diagnostics to EUVE observations of the F5 subgiant Procyon is briefly discussed.

Properties of LBGs with [OIII] detection at z > 3: The importance of including nebular emission data in SED fitting

2019 ◽  
Vol 15 (S341) ◽  
pp. 201-205
Author(s):  
Fang-Ting Yuan ◽  
Denis Burgarella ◽  
David Corre ◽  
Veronique Buat ◽  
Médéric Boquien ◽  
...  
Keyword(s):  
Physical Properties ◽  
Emission Line ◽  
Equivalent Width ◽  
Spectroscopic Data ◽  
Rest Frame ◽  
High Redshift ◽  
Emission Lines ◽  
Emission Data ◽  
Strong Emission ◽  
The Difference

AbstractAt high redshift, the contribution of strong emission lines to the broadband photometry can cause large uncertainties when estimating galaxy physical properties. To examine this effect, we investigate a sample of 54 LBGs at 3 < zspec < 3.8 with detected [OIII] line emissions. We use CIGALE to fit simultaneously the rest-frame UV-to-NIR SEDs of these galaxies and their emission line data. By comparing the results with and without emission line data, we show that spectroscopic data are necessary to constrain the nebular model. We examine the K-band excess, which is usually used to estimate the emissions of [OIII]+Hβ lines when there is no spectral data, and find that the difference between the estimation and observation can reach up to > 1 dex for some galaxies, showing the importance of obtaining spectroscopic measurements of these lines. We also estimate the equivalent width of the Hβ absorption and find it negligible compared to the Hβ emission.

scholarly journals HIGH-RESOLUTION SPECTROSCOPY OF THE B[e] STAR MWC 645

2021 ◽  
Vol 34 ◽  
pp. 59-64
Author(s):  
A.S. Nodyarov ◽  
A.S. Miroshnichenko ◽  
S.A. Khokhlov ◽  
S.V. Zharikov ◽  
N. Manset ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Emission Line ◽  
Spectroscopic Data ◽  
Emission Lines ◽  
Absorption Lines ◽  
High Resolution Spectroscopy ◽  
Cool Component ◽  
Spectroscopic Observations ◽  
First Time

Optical high-resolution spectroscopic observations of the emission-line star MWC645 are presented. The spectrum exhibits strong variable double-peaked Balmer emission lines as well as low-excitation emission lines of FeII, [FeII], and [OI] which are signatures of the B[e] phenomenon, while lines of helium have not been found. In addition to the emission lines, for the first time we identified absorption lines of neutral metals (e.g., LiI 6708  A, CaI 6717 A, and a number of FeI and TiI lines) that indicate the presence of a cool component in the system. The heliocentric radial velocity measured in our best spectrum was found to be −65.1±1.0 kms −1 for the emission lines and −23.2±0.4 kms −1 for the absorption lines. Using a combination of photometric and spectroscopic data as well as the Gaia EDR3 distance (D=6.5±0.9 kpc), we disentangled the component contributions and estimated their temperatures and luminosities (∼15000 K and ∼4000 K, log L/L ? = 3.8±0.2 and 2.8±0.2 for the hot and cool component, respectively).

scholarly journals Gaia-assisted discovery of a detached low-ionisation BAL quasar with very large ejection velocities

2020 ◽  
Vol 634 ◽  
pp. A111 ◽  
Author(s):  
J. P. U. Fynbo ◽  
P. Møller ◽  
K. E. Heintz ◽  
J. N. Burchett ◽  
L. Christensen ◽  
...  
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Emission Lines ◽  
Broad Absorption ◽  
Broad Absorption Line ◽  
Red Edge ◽  
First Case ◽  
Bl Lac ◽  
Spatially Extended ◽  
Extended Emission

We report on the discovery of a peculiar broad absorption line (BAL) quasar identified in our Gaia-assisted survey of red quasars. The systemic redshift of this quasar was difficult to establish because of the absence of conspicuous emission lines. Based on deep and broad BAL troughs of at least Si IV, C IV, and Al III, a redshift of z = 2.41 was established under the assumption that the systemic redshift can be inferred from the red edge of the BAL troughs. However, we observe a weak and spatially extended emission line at 4450 Å that is most likely due to Lyman-α emission, which implies a systemic redshift of z = 2.66 if correctly identified. There is also evidence for the onset of Lyman-α forest absorption bluewards of 4450 Å and evidence for Hα emission in the K band consistent with a systemic redshift of z = 2.66. If this redshift is correct, the quasar is an extreme example of a detached low-ionisation BAL quasar. The BALs must originate from material moving with very large velocities ranging from 22 000 km s−1 to 40 000 km s−1. To our knowledge, this is the first case of a systemic-redshift measurement based on extended Lyman-α emission for a BAL quasar. This method could also be useful in cases of sufficiently distant BL Lac quasars without systemic-redshift information.

scholarly journals The SAMI Galaxy Survey: reconciling strong emission line metallicity diagnostics using metallicity gradients

2021 ◽  
Vol 502 (3) ◽  
pp. 3357-3373
Author(s):  
Henry Poetrodjojo ◽  
Brent Groves ◽  
Lisa J Kewley ◽  
Sarah M Sweet ◽  
Sebastian F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
Electron Temperature ◽  
Gas Phase ◽  
Mass Range ◽  
Accurate Method ◽  
Emission Lines ◽  
Mass Relation ◽  
Strong Emission ◽  
Data Release ◽  
Accurate Comparison

ABSTRACT We measure the gas-phase metallicity gradients of 248 galaxies selected from Data Release 2 of the SAMI Galaxy Survey. We demonstrate that there are large systematic discrepancies between the metallicity gradients derived using common strong emission line metallicity diagnostics. We determine which pairs of diagnostics have Spearman’s rank coefficients greater than 0.6 and provide linear conversions to allow the accurate comparison of metallicity gradients derived using different strong emission line diagnostics. For galaxies within the mass range 8.5 &lt; log (M/M⊙) &lt; 11.0, we find discrepancies of up to 0.11 dex/Re between seven popular diagnostics in the metallicity gradient–mass relation. We find a suggestion of a break in the metallicity gradient–mass relation, where the slope shifts from negative to positive, occurs between 9.5 &lt; log (M/M⊙) &lt; 10.5 for the seven chosen diagnostics. Applying our conversions to the metallicity gradient–mass relation, we reduce the maximum dispersion from 0.11 dex/Re to 0.02 dex/Re. These conversions provide the most accurate method of converting metallicity gradients when key emission lines are unavailable. We find that diagnostics that share common sets of emission line ratios agree best, and that diagnostics calibrated through the electron temperature provide more consistent results compared to those calibrated through photoionization models.

Discovery of five new Galactic symbiotic stars in the VPHAS+ survey

2021 ◽  
Vol 502 (2) ◽  
pp. 2513-2517
Author(s):  
Stavros Akras ◽  
Denise R Gonçalves ◽  
Alvaro Alvarez-Candal ◽  
Claudio B Pereira
Keyword(s):  
Spectroscopic Data ◽  
Selection Criterion ◽  
Optical Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Symbiotic Stars ◽  
Selection Of

ABSTRACT We report the validation of a recently proposed infrared (IR) selection criterion for symbiotic stars (SySts). Spectroscopic data were obtained for seven candidates, selected from the SySt candidates of Akras et al. by employing the new supplementary IR selection criterion for SySts in the VST/OmegaCAM Photometric H-Alpha Survey. Five of them turned out to be genuine SySts after the detection of H α, He ii, and [O iii] emission lines as well as TiO molecular bands. The characteristic O vi Raman-scattered line is also detected in one of these SySts. According to their IR colours and optical spectra, all five newly discovered SySts are classified as S-type. The high rate of true SySts detections of this work demonstrates that the combination of the H α emission and the new IR criterion improves the selection of target lists for follow-up observations by minimizing the number of contaminants and optimizing the observing time.

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 Challenges and Techniques for Simulating Line Emission

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 100 ◽  
Author(s):  
Karen Olsen ◽  
Andrea Pallottini ◽  
Aida Wofford ◽  
Marios Chatzikos ◽  
Mitchell Revalski ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Emission Line ◽  
Line Emission ◽  
Emission Lines ◽  
Synthetic Spectra ◽  
Recent Advances ◽  
The Future ◽  
Important Quality ◽  
Circumgalactic Medium

Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.

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