Variable oxygen emission from the accretion disk of Mrk 110

Six XMM-Newton observations of the bright narrow line Seyfert 1, Mrk 110, from 2004–2020, are presented. The analysis of the grating spectra from the Reflection Grating Spectrometer (RGS) reveals a broad component of the He-like Oxygen (O VII) line, with a full width at half maximum of 15 900 ± 1800 km s−1 measured in the mean spectrum. The broad O VII line in all six observations can be modelled with a face-on accretion disk profile, where from these profiles the inner radius of the line emission is inferred to lie between about 20–100 gravitational radii from the black hole. The derived inclination angle, of about 10 degrees, is consistent with studies of the optical Broad Line Region in Mrk 110. The line also appears variable and for the first time, a significant correlation is measured between the O VII flux and the continuum flux from both the RGS and EPIC-pn data. Thus the line responds to the continuum, being brightest when the continuum flux is highest, similar to the reported behaviour of the optical He II line. The density of the line emitting gas is estimated to be ne ∼ 1014 cm−3, consistent with an origin in the accretion disk.

A flare in the optical spotted in the changing-look Seyfert NGC 3516

Context. 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. Aims. 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. Methods. 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. Results. An increase of the photometric magnitude is seen in both U and B filters to a maximum amplitude of 0.25 mag and 0.11 mag, respectively. During the flare, we observe stronger forbidden high-ionization iron lines ([Fe VII] and [Fe X]) than reported before, as well as the complex broad Hα and Hβ lines. This is especially seen in Hα, which appears to be double-peaked. It seems that a very broad component of ∼10 000 km s−1 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. Conclusions. 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.

Panchromatic properties of the extreme Fe ii emitter PHL 1092

ABSTRACT We present near-infrared spectroscopy of the NLS1 galaxy PHL 1092 (z = 0.394), the strongest Fe ii emitter ever reported, combined with optical and UV data. We modelled the continuum and the broad emission lines using a power-law plus a blackbody function and Lorentzian functions, respectively. The strength of the Fe ii emission was estimated using the latest Fe ii templates in the literature. We re-estimate the ratio between the Fe ii complex centred at 4570 Å and the broad component of H β, R4570, obtaining a value of 2.58, nearly half of that previously reported (R4570 = 6.2), but still placing PHL 1092 among extreme Fe ii emitters. The full width at half-maximum (FWHM) values found for low-ionization lines are very similar (FWHM ∼ 1200 km s−1), but significantly narrower than those of the hydrogen lines (FWHMH β ∼ 1900 km s−1). Our results suggest that the Fe ii emission in PHL 1092 follows the same trend as in normal Fe ii emitters, with Fe ii being formed in the outer portion of the BLR and co-spatial with Ca ii, and O i, while H β is formed closer to the central source. The flux ratio between the UV lines suggests high densities, log(nH) ∼ 13.0 cm−3, and a low ionization parameter, log(U) ∼ −3.5. The flux excess found in the Fe ii bump at 9200 Å after the subtraction of the NIR Fe ii template and its comparison with optical Fe ii emission suggests that the above physical conditions optimize the efficiency of the Ly α-fluorescence process, which was found to be the main excitation mechanism in the Fe ii production. We discuss the role of PHL 1092 in the eigenvector 1 context.

Optical spectroscopy of type 2 LINERs

Context. Type 2 Low-ionization Nuclear Emission-line Regions (LINERs) have been optically classified with the Palomar data as not presenting a broad component in the Balmer emission lines that are associated with the broad-line region (BLR) of the active galactic nuclei (AGN). Aims. We aim to unveil the presence of different kinematic components of emission lines in the nuclear region of a sample of local (z ≤ 0.022) type 2 LINERs. We focus on the analysis of the true nature of LINERs by means of the detection (or nondetection) of a broad component that originated in the BLR of the AGN. Additionally, we search for the possible presence of nonrotational motions such as outflows in these LINERs. Methods. We applied a decomposition of the nuclear emission lines using an spectroscopic analysis of the optical spectra of nine type 2 LINERs of intermediate-resolution spectroscopic data retrieved from the Hubble Space Telescope (HST) archive. The study is completed with archival spectra from the Double Spectrograph from the Palomar Observatory. Results. The emission line fitting reveals the presence of a broad component associated with the BLR in six out of the nine galaxies for the space-based data, and for two out of the eight from the ground-based spectra. The velocity dispersion for two galaxies (NGC 4486 and NGC 4594) measured in HST/STIS data suggest the presence of outflows. Conclusions. The results indicate that the spatial resolution plays a major role in the detection of the BLR, as it appears diluted in the ground-based data (even after removing stellar contribution). This is also true for the emission line diagnostics, as the contaminant light contributes to lower emission line ratios toward the star-forming area of standard BPTs. We propose to reclassify NGC 4594 as a type 1 LINER, since a BLR component is seen in both space- and ground-based spectra. We find ambiguous results for the BLR component of NGC 4486. The modest outflow detection in our sample may indicate that they are not as frequent as seen for type 1 LINERs.

A spectral stacking analysis to search for faint outflow signatures in z ∼ 6 quasars

Aims. Outflows in quasars during the early epochs of galaxy evolution are an important part of the feedback mechanisms that potentially affect the evolution of the host galaxy. However, systematic millimetre (mm) observations of outflows are only now becoming possible with the advent of sensitive mm telescopes. In this study we used spectral stacking methods to search for a faint high-velocity outflow signal in a sample of [C II] detected, z ∼ 6 quasars. Methods. We searched for broad emission line signatures from high-velocity outflows for a sample of 26 z ∼ 6 quasars observed with the Atacama Large Millimeter Array (ALMA), with a detection of the [C II] line. The observed emission lines of the sources are dominated by the host galaxy, and outflow emission is not detected for the individual sources. We used a spectral line stacking analysis developed for interferometric data to search for outflow emission. We stacked both extracted spectra and the full spectral cubes. We also investigated the possibility that only a sub-set of our sample contributes to the stacked outflow emission. Results. We find only a tentative detection of a broad emission line component in the stacked spectra. When taking a region of about 2″ around the central position of the stacked cubes, the stacked line shows an excess emission due to a broad component of 1.1–1.5σ, but the significance drops to 0.4–0.7σ when stacking the extracted spectra from a smaller region. The broad component can be characterised by a line width of full width at half-maximum FWHM > 700 km s−1. Furthermore, we find a sub-sample of 12 sources, the stack of which maximises the broad component emission. The stack of this sub-sample shows an excess emission due to a broad component of 1.2–2.5σ. The stacked line of these sources has a broad component of FWHM > 775 km s−1. Conclusions. We find evidence suggesting the presence of outflows in a sub-sample of 12 out of 26 sources, which demonstrates the importance of spectral stacking techniques in tracing faint signal in galaxy samples. However, deeper ALMA observations are necessary to confirm the presence of a broad component in the individual spectra.

Optical spectroscopy of type-2 LINERs

Low-Ionisation Nuclear Emission-line Regions (LINERs) are the least luminous and the most numerous among the local population of Active Galactic Nuclei (AGN). They can be classified as type-1 or type-2 if their optical spectra show or do not show, respectively, a broad component. It is associated with the presence of a Broad Line Region (BLR) in these systems. However, recent studies have proven that the classification of type-1 LINERs may be controversial, since space- and ground-based spectroscopy provide contradicting results on the presence of very broad components (Cazzoli et al.2018). We have studied the nuclear spectra of 9 type-2 LINERs with intermediate spectral resolution HST/STIS data. We present the results on our analysis of the different spectral components, and discuss the eventual presence of BLR components in type-2 LINER galaxies, together with the possible presence of outflows, both in comparison with type-1 LINERs. We have found a BLR component in 7 out of the 9 analysed objects within the HST/STIS data.

A panchromatic spatially resolved study of the inner 500 pc of NGC 1052 – II. Gas excitation and kinematics

ABSTRACT We map the optical and near-infrared (NIR) emission-line flux distributions and kinematics of the inner 320 × 535 pc2 of the elliptical galaxy NGC 1052. The integral field spectra were obtained with the Gemini Telescope using the GMOS-IFU and NIFS instruments, with angular resolutions of 0.88 and 0.1 arcsec in the optical and NIR, respectively. We detect five kinematic components: (1) and (2) two spatially unresolved components: a broad-line region visible in H α, with a full width at half-maximum (FWHM) of ∼3200 km s−1, and an intermediate broad component seen in the [O iii] λλ4959,5007 doublet; (3) an extended intermediate-width component with 280 km s−1 < FWHM < 450 km s−1 and centroid velocities up to 400 km s−1, which dominates the flux in our data, attributed either to a bipolar outflow related to the jets, rotation in an eccentric disc or to a combination of a disc and large-scale gas bubbles; (4) and (5) two narrow (FWHM < 150 km s−1) components, one visible in [O iii], and another visible in the other emission lines, extending beyond the field of view of our data, which is attributed to large-scale shocks. Our results suggest that the ionization within the observed field of view cannot be explained by a single mechanism, with photoionization being the dominant mechanism in the nucleus with a combination of shocks and photoionization responsible for the extended ionization.

Detection of a double-peaked H α component from the accretion disc of NGC 4958

Active Galactic Nuclei are objects associated with the presence of an accretion disc around supermassive black holes found in the very central region of galaxies with a well-defined bulge. In the optical range of the spectrum, a possible signature of the accretion disc is the presence of a broad double-peaked component that is mostly seen in H α. In this paper, we report the detection of a double-peaked feature in the H α line in the nucleus of the galaxy NGC 4958. The narrow-line region of this object has an emission that is typical of a low-ionization nuclear emission-line region galaxy, which is the usual classification for double-peaked emitters. A central broad component, related to the broad-line region of this object, is seen in H α and also in H β. We concluded that the double-peaked emission is emitted by a circular relativistic Keplerian disc with an inner radius ξi = 570 ± 83, an outer radius ξo = 860 ± 170 (both in units of GMSMBH/c2), an inclination to the line of sight i = 27.2 ± 0.7° and a local broadening parameter σ = 1310 ± 70 km s−1.

The gas distribution and kinematics in the central region of the Seyfert 2 galaxy NGC 1125

We present Gemini Near-Infrared Integral-Field Spectrograph (NIFS) observations of the inner 660 × 660 pc2 of the Seyfert 2 galaxy NGC 1125, which reveals that the emission-line profiles present two kinematic components: a narrow one (σ < 150 km s−1) due to emission of the gas in the disk and a broad component (σ > 150 km s−1) produced by a bipolar outflow, perpendicular to the galaxy’s disk.

Phase transition of BiNb1−xMnxO4−δ: Thermal analyse, NEXAFS, XPS and ESR-study

The manganese-doped polymorphs of bismuth orthoniobate were studied using thermal analysis, ESR, XPS and NEXAFS spectroscopy. It was shown that the phase transition from the orthorhombic (α) to the triclinic (β) modification can be reversible and it can be achieved by prolonged calcination of samples at 750°C. The DSC curves revealed no thermal effects associated with the phase transformation from the triclinic to the orthorhombic modification near 750°C. In the ESR spectra, the absorption band with g = 3.8 characterized by sextet structure disappeared during the phase transformation from the - to the -form and only the broad component with average intensity was observed at g = 2.2-2.0. According to NEXAFS spectroscopy data, the content of oxidized Mn(III) atoms increased and the content of Mn(II) decreased in the orthorhombic polymorph obtained at 750°C from the tri-clinic modification.