- ID:
- ivo://CDS.VizieR/J/A+A/550/A12
- Title:
- NGC253 near-infrared H_2_ emission
- Short Name:
- J/A+A/550/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Because of its large angular size and proximity to the Milky Way, NGC 253, an archetypal starburst galaxy, provides an excellent laboratory to study the intricacies of this intense episode of star formation. We aim to characterize the excitation mechanisms driving the emission in NGC 253. Specifically we aim to distinguish between shock excitation and ultraviolet (UV) excitation as the dominant driving mechanism, using Br{gamma}, H_2_ and [FeII] as diagnostic emission line tracers.
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- ID:
- ivo://CDS.VizieR/J/A+A/638/A13
- Title:
- NGC 3516 optical flare
- Short Name:
- J/A+A/638/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations from the short-term intensive optical campaign (from September 2019 to January 2020) of the changing-look Seyfert NGC 3516. This active galactic nucleus is known to have strong optical variability and has changed its type in the past. It has been in the low-activity state in the optical since 2013, with some rebrightening from the end of 2015 to the beginning of 2016, after which it remained dormant. We aim to study the photometric and spectral variability of NGC 3516 from the new observations in U- and B-bands and examine the profiles of the optical broad emission lines in order to demonstrate that this object may be entering a new state of activity. NGC 3516 has been monitored intensively for the past 4 months with an automated telescope in U and B filters, enabling accurate photometry of 0.01 precision. Spectral observations were triggered when an increase in brightness was spotted. We support our analysis of past-episodes of violent variability with the UV and X-ray long-term light curves constructed from the archival Swift/UVOT and Swift/XRT data. An increase of the photometric magnitude is seen in both U and B filters to a maximum amplitude of 0.25mag and 0.11mag, respectively. During the flare, we observe stronger forbidden high-ionization iron lines ([FeVII] and [FeX]) than reported before, as well as the complex broad H{alpha} and H{beta} lines. This is especially seen in H{alpha}, which appears to be double-peaked. It seems that a very broad component of ~10000km/s in width in the Balmer lines is appearing. The trends in the optical, UV, and X-ray light curves are similar, with the amplitudes of variability being significantly larger in the case of UV and X-ray bands. The increase of the continuum emission, the variability of the coronal lines, and the very broad component in the Balmer lines may indicate that the AGN of NGC 3516 is finally leaving the low-activity state in which it has been for the last ~3 years.
- ID:
- ivo://CDS.VizieR/J/A+A/314/43
- Title:
- NGC 5548 Profile variability
- Short Name:
- J/A+A/314/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical emission line intensities of the variable Seyfert 1 galaxy NGC 5548 are presented.
- ID:
- ivo://CDS.VizieR/J/A+A/371/79
- Title:
- NGC 5548 UBVRI phot. and Halpha, Hbeta fluxes
- Short Name:
- J/A+A/371/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of a ground-based optical monitoring campaign on NGC 5548 in June 1998 are presented. The broad-band fluxes (U, B, V), and the spectrophotometric optical continuum flux F_{lambda}_ (5100{AA}) monotonically decreased in flux while the broad-band R and I fluxes and the integrated emission-line fluxes of H{alpha} and H{beta} remained constant to within 5%. On June 22, a short continuum flare was detected in the broad band fluxes. It had an amplitude of about ~18% and it lasted only =~90 min. The broad band fluxes and the optical continuum F_{lambda}_ (5100{AA}) appear to vary simultaneously with the EUV variations. No reliable delay was detected for the broad optical emission lines in response to the EUVE variations. Narrow H{beta} emission features predicted as a signature of an accretion disk were not detected during this campaign. However, there is marginal evidence for a faint feature at {lambda}=~4962{AA} with FWHM=~6{AA} redshifted by {Delta}v=~1100km/s with respect to H{beta}_narrow_.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A41
- Title:
- NGC 5427 WiFeS data cubes
- Short Name:
- J/A+A/566/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed the nearby, nearly face-on, Seyfert 2 galaxy, NGC 5427, using optical integral field spectroscopy of both the nuclear regions and the HII regions in the spiral arms. The observed spectra have been modelled using the MAPPINGS IV photoionisation code, both to derive the chemical abundances in the HII regions and the Seyfert nucleus, and to constrain the EUV spectral energy distribution of the AGN illuminating the extended narrow-line region.
- ID:
- ivo://CDS.VizieR/J/A+A/560/A99
- Title:
- NIR long-slit spectra of Seyfert galaxies
- Short Name:
- J/A+A/560/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The excitation of the gas phase of the interstellar medium can be driven by various mechanisms. In galaxies with an active nucleus, such as Seyfert galaxies, both radiative and mechanical energy from the central black hole, or the stars in the disk surrounding it may play a role. We investigate the relative importance and range of influence of the active galactic nucleus for the excitation of ionized and molecular gas in the central kiloparsec of its host galaxy. We present H- and K-band long-slit spectra for a sample of 21 nearby (D<70Mpc) Seyfert galaxies obtained with the NIRSPEC instrument on the Keck telescope. For each galaxy, we fit the nebular line emission, stellar continua, and warm molecular gas as a function of distance from the nucleus.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/L113
- Title:
- Nitrogen abundance of Seyfert 2 AGN
- Short Name:
- J/MNRAS/468/L113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained new quantitative determinations of the nitrogen abundance and a consistent relation between the nitrogen and oxygen abundances for a sample of Seyfert 2 galaxies located at redshift z<0.1. We carried out this analysis using the CLOUDY code to build detailed photoionization models. We were able to reproduce observed optical narrow emission line intensities for 44 sources compiled from the literature. Our results show that Seyfert 2 nuclei have nitrogen abundances ranging from ~0.3 to ~7.5 times the solar value. We derived the relation log (N/H)=1.05(+/-0.09)x[log(O/H)]-0.35(+/-0.33). Results for N/O versus O/H abundance ratios derived for Seyfert 2 galaxies are in consonance with those recently derived for a sample of extragalactic disc HII regions with high metallicity.
98. NLS1 at 37GHz
- ID:
- ivo://CDS.VizieR/J/A+A/614/L1
- Title:
- NLS1 at 37GHz
- Short Name:
- J/A+A/614/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected six narrow-line Seyfert 1 (NLS1) galaxies at 37GHz that were previously classified as radio silent and two that were classified as radio quiet. These detections reveal the presumption that NLS1 galaxies labelled radio quiet or radio silent and hosted by spiral galaxies are unable to launch jets to be incorrect. The detections are a plausible indicator of the presence of a powerful, most likely relativistic jet because this intensity of emission at 37GHz cannot be explained by, for example, radiation from supernova remnants. Additionally, one of the detected NLS1 galaxies is a newly discovered source of gamma rays and three others are candidates for future detections.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/942
- Title:
- Nuclear activity of NGC 5548
- Short Name:
- J/PAZh/27/942
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI observations of the nucleus of the Seyfert galaxy NGC 5548 from 1990 until 2000 at four astronomical observatories are given in Table2. All data have been reduced to a single system and are given for an A=14.3" aperture.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/83
- Title:
- Nuclear activity of NGC 4151 in 1989-2000
- Short Name:
- J/PAZh/27/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband UBVRI observations of the nucleus of the Seyfert galaxy NGC 4151 from 1989 until 2000 at three astronomical observatories: the Crimean Station of the Sternberg astronomical institute, The Special Astronomical observatory in the Caucasus and the Maidanac observatory of the Ulugbek Astronomical institute in Uzbekistan. All data have been reduced to a single system and are given for an A=27.5" aperture.
