Λ5007 Emission Line Research Articles

Determining star formation rates in AGN hosts from strong optical emission lines

ABSTRACT The influence of Active Galactic Nuclei (AGN) on star formation within their host galaxies remains a topic of intense debate. One of the primary challenges in quantifying the star formation rate (SFR) within AGN hosts arises from the prevalent assumption in most methodologies, which attribute gas excitation to young stars alone. However, this assumption does not consider the contribution of the AGN to the ionization of the gas in their environment. To address this issue, we evaluate the use of strong optical emission lines to obtain the SFR surface density ($\Sigma {{\rm SFR_{AGN}}}$) in regions predominantly ionized by an AGN, using a sample of 293 AGN hosts from the MaNGA survey, with SFR measurements available through stellar population fitting. We propose calibrations involving the H$\alpha$ and [O iii]$\lambda$5007 emission lines, which can be used to determine $\Sigma {{\rm SFR_{AGN}}}$, resulting in values consistent with those estimated through stellar population fitting.

Narrow [O iii] Emission Lines as a Potential Proxy for the Evolutionary Stage of Quasars

Radio spectral shape of quasars can provide insight into the ages of quasars. We have compiled data for 1804 quasars with z ≲ 1 from the Sloan Digital Sky Survey (SDSS). Additionally, these quasars were also mapped by the Low-Frequency Array at 144 MHz and the Very Large Array Sky Survey at 3000 MHz. The radio spectral index, designated as α3000144 (with S(ν) ∝ ν α ), is analyzed between 144 and 3000 MHz as a proxy for the ages of quasars. We measure the [O III] λ5007 emission line in the SDSS spectra. A strong correlation was found between the equivalent width of the core component of the [O III] λ5007 emission line and α3000144 . This relationship suggests that the core component of the [O III] λ5007 emission line could potentially serve as a surrogate for the evolutionary stage of a quasar. The quasars at an early stage of evolutions tend to show weaker [O III] λ5007 emission, while older quasars exhibit stronger [O III] λ5007 emission.

AT2023vto: An Exceptionally Luminous Helium Tidal Disruption Event from a Massive Star

We present optical/UV observations and the spectroscopic classification of the transient AT2023vto as a tidal disruption event (TDE) at z = 0.4846. The spectrum is dominated by a broad blueshifted He ii λ4686 emission line, classifying it as a member of the TDE-He class. The light curve exhibits a persistent blue color of g − r ≈ −0.4 mag, long rise, and decline timescale, with a large peak absolute magnitude of M g ≈ −23.2, making it the most luminous of the classical optical TDEs (H, H+He, He) discovered to date by about 1.5 mag. We identify the host galaxy of AT2023vto in archival Pan-STARRS images and find that the transient is located at the galaxy center. Modeling the light curves of AT2023vto, we find that it resulted from the disruption of a ≈8 M ⊙ star by a ≈107 M ⊙ supermassive black hole. The star mass is about 5 times larger than the highest star masses previously inferred in TDEs, and the black hole mass is at the high end of the distribution. AT2023vto is comparable in luminosity and timescale to some putative TDEs (blue featureless continuum), as well as to the mean of a recently identified population of ambiguous nuclear transients (ANTs). ANTs have been speculated to arise from tidal disruptions of massive stars, perhaps in active galactic nuclei, and AT2023vto may represent a similar case to ANTs but in a dormant black hole, thereby bridging the TDE and ANT populations. We anticipate that the Rubin Observatory/LSST will uncover similar luminous TDEs to z ∼ 3.

QSOFEED: Relationship between star formation and active galactic nuclei feedback

Context. Large-scale cosmological simulations suggest that feedback from active galactic nuclei (AGN) plays a crucial role in galaxy evolution. More specifically, outflows are one of the mechanisms by which the accretion energy of the AGN is transferred to the interstellar medium (ISM), heating and driving out gas and impacting star formation (SF). Aims. The purpose of this study is to directly test this hypothesis utilising SDSS spectra of a well-defined sample of 48 low-redshift (z < 0.14) type 2 quasars (QSO2s). Methods. By exploiting these data, we were able to characterise the kinematics of the warm ionised gas by performing a non-parametric analysis of the [OIII]λ5007 emission line. We also constrained the properties of the young stellar populations (YSP; tysp < 100 Myr) of their host galaxies via spectral synthesis modelling. Results. These analyses revealed that 85% of the QSO2s display velocity dispersions in the warm ionised gas phase greater than that of the stellar component of their host galaxies, indicating the presence of AGN-driven outflows. We compared the gas kinematics with the intrinsic properties of the AGN and found that there is a positive correlation between gas velocity dispersion and 1.4 GHz radio luminosity – but not with the AGN bolometric luminosity or Eddington ratio. This either suggests that the radio luminosity is the key factor driving outflows or that the outflows themselves are shocking the ISM and producing synchrotron emission. We found that 98% of the sample host YSPs to varying degrees, with star formation rates (SFRs) of 0 ≤ SFR ≤ 92 M⊙ yr−1, averaged over 100 Myr. We compared the gas kinematics and outflow properties to the SFRs to establish possible correlations that could suggest that the presence of the outflowing gas could be impacting SF, but we found that no such correlation exists. This leads us to the conclusion that on the scales probed by the SDSS fibre (between 2 and 7 kpc diameters), AGN-driven outflows do not impact SF on the timescales probed in this study. However, we find a positive correlation between the light-weighted stellar ages of the QSO2s and the black hole mass, which might indicate that successive AGN episodes lead to the suppression of SF over the course of galaxy evolution.

Testing He ii Emission from Wolf–Rayet Stars as a Dust Attenuation Measure in Eight Nearby Star-forming Galaxies

The ability to determine galaxy properties such as masses, ages, and star formation rates robustly is critically limited by the ability to measure dust attenuation accurately. Dust reddening is often characterized by comparing observations to models of either nebular recombination lines or the UV continuum. Here, we use a new technique to measure dust reddening by exploiting the He ii λ1640 and λ4686 emission lines originating from the stellar winds of Wolf–Rayet stars. The intrinsic line ratio is determined by atomic physics, enabling an estimate of the stellar reddening similar to how the Balmer lines probe gas-emission reddening. The He ii line ratio is measured from UV and optical spectroscopy using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope for eight nearby galaxies hosting young massive star clusters. We compare our results to dust reddening values estimated from UV spectral slopes and from Balmer line ratios and find tentative evidence for systematic differences. The reddening derived from the He ii lines tends to be higher, whereas that from the UV continuum tends to be lower. A larger sample size is needed to confirm this trend. If confirmed, this may indicate an age sequence probing different stages of dust clearing. Broad He ii lines have also been detected in galaxies more distant than in our sample, providing the opportunity to estimate the dust reddening of the youngest stellar populations out to distances of ∼100 Mpc.

Chemical Abundances of a Sample of Oxygen-dominated Galaxies

We spectroscopically analyzed a sample of 85 Sloan Digital Sky Survey compact, oxygen-dominated galaxies located at redshift z ∼ 0.001–0.350, selected because of their large equivalent width of [O iii]λ5007 (larger than 200 Å). These galaxies might be considered as extreme emission-line galaxies due to their strong [O iii]λ5007 emission line. We detected high-ionization lines, even those related to the presence of Wolf–Rayet stars, in almost all the galaxies studied. We obtained physical properties (electron density and temperature) as well as chemical abundances by using the direct method based on the electron temperature. In this analysis, we obtained three different measurements of T(high): the usual one, T([O iii]), but also that of T([S iii]) and T([Ar iii]) for five and three of the galaxies, respectively. Further, we established a new calibration for T([S iii]). We determined oxygen, nitrogen, sulfur, neon, argon, iron, and chlorine abundances when possible, and we compared to the results of other late-type, low-metallicity galaxies, such as blue compact dwarfs, Ims, and green peas. From such a detailed study, we can conclude that the majority of the galaxies in this sample have similar metallicities to the SMC (about ) ≈ 8 dex), and that only 12% of the galaxies are extremely metal-poor, with abundances lower than 7.7 dex. Also, a comparison with some chemical evolution models as well as a brief discussion on the chemical evolution with time is considered.

Ionized-gas Metallicity of the Strong [O iii]λ5007 Emission-line Compact Galaxies in the LAMOST Survey

This article reports a sample of 1830 strong [O iii]λ5007 emission-line compact galaxies discovered with the LAMOST spectroscopic survey and the photometric catalog of the Sloan Digital Sky Survey. We newly identify 402 spectra of 346 strong [O iii]λ5007 emission-line compact galaxies by finding compact isolated point sources. Combined with the samples in our previous work, this returns a sample of 1830 unique strong [O iii]λ5007 emission-line compact galaxies with 2033 spectra of z ≤ 0.53. For the sources with 2σ[O iii]λ4363 detections, we calculate the gas-phase metallicity with the direct-T e method, and verify that the strong-line metallicity diagnostics calibrated with the direct-T e method also applies to this sample. The strong [O iii]λ5007 emission-line compact galaxies fall below several T e -calibrated mass–metallicity relations. The N/O measurements of the strong [O iii]λ5007 emission-line compact galaxies mainly locate at a plateau at low metallicity, indicating the product of primary nucleosynthesis. The Ne3O2 and O32 relation follows a tight linear relation with no redshift evolution. The Ne3O2 anticorrelates with the stellar mass, and at fixed stellar mass the Ne3O2 increases with the redshift. Eight sources with asymmetric [O iii]λ5007 emission-line profiles have been identified, however with no [O iii]λ4363 detection, which proves the rich metal content and complex ionized-gas kinematics within the galaxies. Higher-resolution spectroscopy will be necessary to identify the ionized-gas components in detail.

The impact of environmental effects on active galactic nuclei: A decline in the incidence of ionized outflows

Active galactic nuclei (AGNs) have generally been considered to be less frequent in denser environments due to a lower number of galaxy-galaxy interactions and/or the removal of their gas-rich reservoirs by the dense intergalactic medium. However, recent observational and theoretical works suggest that the effect of ram-pressure stripping acting on galaxies in dense environments might reduce the angular momentum of their gas, causing it to infall towards the super massive black hole at their centre, activating the AGN phase. In this work we explore the connection between environment and nuclear activity by evaluating the variation in the incidence of ionized outflows, a common phenomenon associated with nuclear activity, in AGNs across different environments. We select a sample of approximately 3300 optical AGNs from the Sloan Digital Sky Survey Data Release 13, which we match with a group catalogue to identify galaxies in isolation or residing in groups. We further probe their environments through the projected distance to the central galaxy of the group or cluster and the projected surface density to the fifth neighbour (δ5). The presence of ionized outflows is determined through the modelling of the [O III] λ5007 emission line. We find that at lower masses (< 1010.3 M⊙), the fraction of ionized outflows is significantly lower in satellite AGNs (∼7%) than in isolated (∼22%) AGNs, probably due to their different AGN luminosity, L[O III], in this stellar mass range. The fraction of outflows decreases at distances closer to the central galaxy of the group or cluster for all satellite AGNs; however, only the lower-mass ones (109 − 1010.3 M⊙) display a significant decline with δ5. Although this study does not include AGNs in the densest regions of galaxy clusters, our findings suggest that AGNs in dense environments accrete less gas than those in the field, potentially due to the removal of the gas reservoirs via stripping or starvation, leading to a negative connection between environment and AGN activity. Based on our results, we propose that the observed change in the incidence of outflows when moving towards denser regions of groups and clusters could contribute to the higher gas metallicities of cluster galaxies compared to field galaxies, especially at lower masses.

The long-term broad-line responsivity in MKN 110

ABSTRACT We examine the long-term history of the optical spectrum of the extremely variable Active Galactic Nucleus (AGN) MKN 110. By combining various archival data with new data, we cover an unprecedented long period of ∼30 yr (1987–2019). We find that the He ii λ4686 emission line changes by a factor of forty and varies more strongly than the optical continuum. Following Ferland et al., we take He ii λ4686 as a proxy for the FUV continuum and compare the flux of several other line species against it. This comparison reveals a clear pattern, whereby lines respond close to linearly at low FUV fluxes, and saturate at high FUV fluxes. The saturation level of the response appears to depend on the excitation energy of the line species. In addition to this global pattern, we note changes among observational epochs, indicating a structural evolution in the broad line region (BLR). The line profiles in our spectra show an offset between the narrow and broad components of the He ii λ4686 and H β lines. This offset shows a significant negative correlation with the FUV flux and a positive correlation with the line velocity width. Our analysis reveals a complex BLR response to a changing continuum. The clear presence of a non-responsive component of the broad lines indicates the existence of multiple contributions to the line emission. We find there are several kinematic models of the BLR and inner regions of the AGN that match our data.

Deep Narrowband Photometry of the M101 Group: Strong-line Abundances of 720 H ii Regions

We present deep, narrowband imaging of the nearby spiral galaxy M101 and its satellites to analyze the oxygen abundances of their H ii regions. Using Case Western Reserve University’s Burrell Schmidt telescope, we add to the narrowband data set of the M101 Group, consisting of Hα, Hβ, and [O iii] emission lines and the blue [O ii] λ3727 emission line for the first time. This allows for complete spatial coverage of the oxygen abundance of the entire M101 Group. We used the strong-line ratio R 23 to estimate oxygen abundances for the H ii regions in our sample, utilizing three different calibration techniques to provide a baseline estimate of the oxygen abundances. This results in ∼650 H ii regions for M101, 10 H ii regions for NGC 5477, and ∼60 H ii regions for NGC 5474, the largest sample for this Group to date. M101 shows a strong abundance gradient, while the satellite galaxies present little or no gradient. There is some evidence for a flattening of the gradient in M101 beyond R ∼ 14 kpc. Additionally, M101 shows signs of azimuthal abundance variations to the west and southwest. The radial and azimuthal abundance variations in M101 are likely explained by an interaction it had with its most massive satellite, NGC 5474, ∼300 Myr ago combined with internal dynamical effects such as corotation.

Finding of a Population of Active Galactic Nuclei Showing a Significant Luminosity Decline in the Past ∼103–104 yr

Recent observations have revealed an interesting active galactic nucleus (AGN) subclass that shows strong activity at large scales (∼1 kpc) but weaker at small scales (<10 pc), suggesting a strong change in the mass accretion rate of the central engine in the past 103–104 yr. We systematically search for such declining or fading AGNs by cross-matching the Sloan Digital Sky Survey type 1 AGN catalog at z < 0.4, covering the [O iii] λ5007 emission line, which is a tracer for the narrow-line region emission, with the Wide-field Infrared Survey Explorer (WISE) mid-infrared (MIR) catalog covering the emissions from the dusty tori. Out of the 7653 sources, we found 57 AGNs whose bolometric luminosities estimated from the MIR band are at least one order of magnitude fainter than those estimated from the [O iii] λ5007 emission line. This luminosity-declining AGN candidate population shows four important properties: (1) the past AGN activity estimated from the [O iii] λ5007 line reaches approximately the Eddington limit; (2) more than 30% of the luminosity-declining AGN candidates show a large absolute variability of ΔW1 > 0.45 mag in the previous ∼10 yr at the WISE 3.4 μm band; (3) the median ratio of log([N ii] λ6584/Hα λ6563) = −0.52, suggesting a lower gas metallicity and/or higher ionization parameter compared to other AGN populations; and (4) the second-epoch spectra of the population indicate a spectral type change for 15% of the sources. This population provides insights on the possible connection between the luminosity decline that started ∼103–104 yr ago and the decline in the recent 10 yr.

Optical Characterization of Two Cataclysmic Variables: RBS 0490 and SDSS J075939.79+191417.3

We present optical photometric and spectroscopic observations of two cataclysmic variables (CVs), namely RBS 0490 and SDSS J075939.79+191417.3. The optical variations of RBS 0490 have been found to occur with a period of 1.689 ± 0.001 hr, which appears to be the probable orbital period of the system. Present photometric observations of SDSS J075939.79+191417.3 confirm and refine the previously determined orbital period as 3.14240928 ± 0.00000096 hr. The presence of long-duration eclipse features in the light curves of SDSS J075939.79+191417.3 indicates that eclipses might be due to an accretion disk and bright spot. The orbital inclination of SDSS J075939.79+191417.3 is estimated to be ∼78° using the eclipse morphology. The phased light-curve variations during the orbital cycle of RBS 0490 provide evidence of emission from an independent second accretion region or a second fainter pole. Optical spectra of RBS 0490 and SDSS J075939.79+191417.3 show the presence of strong Balmer and weak He ii (λ4686) emission lines, along with the detection of strong Hβ emission lines with a large equivalent width. The characteristic features of RBS 0490 seem to favor low-field polars, while SDSS J075939.79+191417.3 appears to be similar to nonmagnetic systems.

The Close AGN Reference Survey (CARS)

Context.The strong asymmetry in the optical [O III]λ5007 emission line is one of the best signatures of active galactic nuclei (AGN) driven warm (∼104K) ionized gas outflows on host galaxy scales. While large spectroscopic surveys such as the sloan digital sky survey (SDSS) have characterized the kinematics of [O III] for large samples of AGN, estimating the associated energetics requires spatially resolving these outflows with, for example, integral field unit (IFU) studies.Aims.As part of the Close AGN Reference Survey, we obtained spatially resolved IFU spectroscopy for a representative sample of 39 luminous type 1 AGN at 0.01 &lt; z &lt; 0.06 with the multi unit spectroscopic explorer and the visible multi object spectrograph IFUs at the very large telescope to infer the spatial location of the ionized gas outflows.Methods.We compared the 2D light distributions of the [O III] wing to that of the Hβbroad emission line region, a classical point source (PSF). We then used the PSF to distinguish between the unresolved and resolved [O III] wing emission. We further determined its location using spectro-astrometry for the point-like sources.Results.The [O III] wing is spatially unresolved in 23 out of the 36 AGN with &gt; 80% of the flux associated with a point-like source. We measured &lt; 100 pc offsets in the spatial location of the outflow from the AGN nucleus using the spectro-astrometry technique for these sources. For the other 13 AGN, the [O III] wing emission is resolved and possibly extended on several kiloparsec scales.Conclusions.We conclude that [O III] wing emission can be compact or extended in an unbiased luminous AGN sample, where both cases are likely to appear. Electron density in the compact [O III] wing regions (medianne ∼ 1900 cm−3) is nearly a magnitude higher than in the extended ones (medianne ∼ 500 cm−3). The presence of spatially extended and compact [O III] wing emission is unrelated to the AGN bolometric luminosity and to inclination effects, which means other features such as time delays, or mechanical feedback (radio jets) may shape the ionized gas outflow properties.

Determining Star Formation Rates of Active Galactic Nucleus Host Galaxies Based on SED Fitting with Submillimeter Data

Abstract We present the star formation rate (SFR) measurements based on the spectral energy distribution (SED) analysis with new submillimeter fluxes combined with archival multiwavelength data for a sample of 52 active galactic nucleus (AGN) host galaxies at z &lt; 0.2. We carried out submillimeter observations using the SCUBA-2 camera at the James Clerk Maxwell Telescope and obtained flux or an upper limit at 450 and 850 μm for each target. By experimenting with the effect of the AGN dust component in the SED fit, we find that the dust luminosity can be overestimated if the AGN contribution is ignored. While the SFR based on the 4000 Å break shows a significant offset compared to the dust-luminosity-based SFR, the SFR obtained by the artificial neural network generally shows consistency, albeit with a large scatter. We find that SFR correlates with the AGN outflow strength manifested by the [O iii] λ5007 emission line, and that AGNs with higher Eddington ratios and stronger outflows are generally hosted by galaxies with a higher SFR, which is consistent with the correlation reported by Woo et al. This suggests no instantaneous quenching of star formation due to AGN feedback.

Strong [O iii] λ5007 Emission-line Compact Galaxies in LAMOST DR9: Blueberries, Green Peas, and Purple Grapes

Abstract Green Pea and Blueberry galaxies are well known for their compact size, low mass, strong emission lines, and analogs to high-z Lyα-emitting galaxies. In this study, 1547 strong [O iii] λ5007 emission-line compact galaxies with 1694 spectra are selected from LAMOST DR9 at the redshift range from 0.0 to 0.59. According to the redshift distribution, these samples can be separated into three groups: Blueberries, Green Peas, and Purple Grapes. Optical [Mg ii] λ2800 line feature, BPT diagram, multiwavelength spectral energy distribution (SED) fitting, mid-IR (MIR) color, and MIR variability are deployed to identify 23 active galactic nucleus candidates from these samples, which are excluded for the following star formation rate (SFR) discussions. We perform the multiwavelength SED fitting with GALEX UV and WISE MIR data. Color excess from the Balmer decrement shows that these strong [O iii] λ5007 emission-line compact galaxies are not highly reddened. The stellar mass of the galaxies is obtained by fitting LAMOST calibrated spectra with the emission lines masked. We find that the SFR is increasing with the increase of redshift, while for the sources within the same redshift bin the SFR increases with mass with a similar slope to the star-forming main sequence. These samples have a median metallicity of 12 + log(O/H) of 8.10. The metallicity increases with mass, and all the sources are below the mass–metallicity relation. The direct-derived T e -based metallicity from the [O iii] λ4363 line agrees with the empirical N2-based empirical gas-phase metallicity. Moreover, these compact strong [O iii] λ5007 lines are mostly in a less dense environment.

Spatially resolved evidence of the impact of quasar-driven outflows on recent star formation: the case of Mrk 34

ABSTRACT We present the results of our spatially resolved investigation into the interplay between the ages of the stellar populations and the kinematics of the warm ionized outflows in the well-studied type II quasar Markarian 34 (Mrk 34). Utilizing integral field spectroscopy data, we determine the spatial distribution of the young stellar population (YSP; tYSP &amp;lt; 100 Myr) using spectral synthesis modelling. We also employ the [O iii] λ5007 emission line as a tracer of the warm ionized gas kinematics. We demonstrate a spatial correlation between the outer edges of the blue side of the outflow and an enhancement in the proportion of the YSP flux, suggesting that the outflow is responsible for triggering star formation in this region. In regions with more highly disrupted gas kinematics, we find that the proportion of YSP flux is consistent with that found outside the outflow region, suggesting that the increased disruption is preventing a similar enhancement in star formation from occurring. Our analysis suggests that Mrk 34 is an example of quasar-driven outflows simultaneously producing both ‘positive’ and ‘preventive’ feedback, further demonstrating the complex nature of the relationship between quasars and their host galaxies.

SDSS-IV MaNGA: Observational Evidence of a Density-bounded Region in a Lyα Emitter

Abstract Using integral field unit spectroscopy, we present here the spatially resolved morphologies of [S ii]λ6717,6731/Hα and [S ii]λ6717,6731/[O iii]λ5007 emission line ratios for the first time in a blueberry Lyα emitter (BBLAE) at z ∼ 0.047. Our derived morphologies show that the extreme starburst region of the BBLAE, populated by young (≤10 Myr), massive Wolf–Rayet stars, is [S ii] deficient, while the rest of the galaxy is [S ii] enhanced. We infer that the extreme starburst region is density-bounded (i.e., optically thin to ionizing photons), and the rest of the galaxy is ionization-bounded, indicating a Blister-type morphology. We find that the previously reported small escape fraction (10%) of Lyα photons is from our identified density-bounded H ii region of the BBLAE. This escape fraction is likely constrained by a porous dust distribution. We further report a moderate correlation between [S ii] deficiency and inferred Lyman continuum (LyC) escape fraction using a sample of confirmed LyC leakers studied in the literature, including the BBLAE studied here. The observed correlation also reveals its dependency on the stellar mass and gas-phase metallicity of the leaky galaxies. Finally, the future scope and implications of our work are discussed in detail.

Fitting spectral energy distributions of FMOS-COSMOS emission-line galaxies atz∼ 1.6: Star formation rates, dust attenuation, and [OIII]λ5007 emission-line luminosities

We perform a spectral energy distribution fitting analysis on a COSMOS photometric sample covering the ultra-violet up to the far-infrared wavelengths and including emission lines from the Fiber Multi-Object Spectrograph survey. The sample consists of 182 objects with Hαand [OIII]λ5007 emission line measurements lying in a redshift range of 1.40 &lt; z &lt; 1.68. We obtain robust estimates of the stellar mass and star-formation rate spanning over a range of 109.5 − 1011.5M⊙and 101 − 103M⊙yr−1from the Bayesian analysis performed with CIGALE and using continuum photometry and Hαfluxes. Combining photometry and spectroscopy gives secure estimations of the amount of dust attenuation for both continuum and line emissions. We obtain a median attenuation ofAHα = 1.16 ± 0.19 mag andA[OIII] = 1.41 ± 0.22 mag. Hαand [OIII]λ5007 attenuations are found to increase with stellar mass, confirming previous findings with Hα. A difference of 57% in the attenuation experienced by emission lines and continuum is found to be in agreement with the emission lines being more attenuated than the continuum emission. Implementation of new CLOUDY HII-region models in CIGALE enables good fits of the Hα, Hβ, [OIII]λ5007 emission lines with discrepancies smaller than 0.2 dex in the predicted fluxes. Fitting the [NII]λ6584 line is found challenging due to well-known discrepancies in the locus of galaxies in the [NII]-BPT diagram at intermediate and high redshifts. We find a positive correlation between SFR andL[OIII]λ5007 after correcting for dust attenuation and we derive the linear relation log10(SFR/M⊙yr−1)=log10(L[OIII]/ergs s−1)−(41.20 ± 0.02). Leaving the slope as a free parameter leads to log10(SFR/M⊙yr−1)=(0.83 ± 0.06)log10(L[OIII]/ergs s−1)−(34.01 ± 2.63). The spread in the relation is driven by differences in the gas-phase metallicity and ionization parameter accounting for a 0.24 dex and 1.1 dex of the dispersion, respectively. We report an average value of logU ≈ −2.85 for this sample of galaxies. Including HII-region models to fit simultaneously photometric data and emission line fluxes is paramount to analyses of upcoming data sets from large spectroscopic surveys of the future, such as MOONS and PFS.

The MURALES survey

We analyze VLT/MUSE observations of 37 radio galaxies from the Third Cambridge catalogue (3C) with redshift &lt; 0.3 searching for nuclear outflows of ionized gas. These observations are part of the MURALES project (a MUse RAdio Loud Emission line Snapshot survey), whose main goal is to explore the feedback process in the most powerful radio-loud AGN. We applied a nonparametric analysis to the [O III] λ5007 emission line, whose asymmetries and high-velocity wings reveal signatures of outflows. We find evidence of nuclear outflows in 21 sources, with velocities between ∼400 and 1000 km s−1, outflowing masses of ∼105 − 107 M⊙, and a kinetic energy in the range ∼1053 − 1056 erg. In addition, evidence for extended outflows is found in the 2D gas velocity maps of 13 sources of the subclasses of high-excitation (HEG) and broad-line (BLO) radio galaxies, with sizes between 0.4 and 20 kpc. We estimate a mass outflow rate in the range 0.4–30 M⊙ yr−1 and an energy deposition rate of Ėkin ∼ 1042 − 1045 erg s−1. Comparing the jet power, the nuclear luminosity of the active galactic nucleus, and the outflow kinetic energy rate, we find that outflows of HEGs and BLOs are likely radiatively powered, while jets likely only play a dominant role in galaxies with low excitation. The low loading factors we measured suggest that these outflows are driven by momentum and not by energy. Based on the gas masses, velocities, and energetics involved, we conclude that the observed ionized outflows have a limited effect on the gas content or the star formation in the host. In order to obtain a complete view of the feedback process, observations exploring the complex multiphase structure of outflows are required.

Discovery of optical outflows and inflows in the black hole candidate GRS 1716−249

ABSTRACT We present optical spectroscopy obtained with the GTC, VLT, and SALT telescopes during the decline of the 2016–2017 outburst of the black hole candidate GRS 1716−249 (Nova Oph 1993). Our 18-epoch data set spans 6 months and reveals that the observational properties of the main emission lines are very variable, even on time-scales of a few hours. Several epochs are characterized by P-Cyg (as well as flat-top and asymmetric) profiles in the Hα, Hβ, and He ii (λ4686) emission lines, implying the presence of an accretion disc wind, which is likely hot and dense. The wind’s terminal velocity (∼2000 km s−1) is similar to that observed in other black hole X-ray transients. These lines also show transient and sharp red-shifted absorptions, taking the form of inverted P-Cyg profiles. We argue that these profiles can be explained by the presence of infalling material at ∼1300 km s−1. We propose a failed wind scenario to explain this inflow and discuss other alternatives, such as obscuration produced by an accretion-related structure (e.g. the gas stream) in a high inclination system.