Absorption Outflows Research Articles

AGN STORM 2. VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations* * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO-16196, and archival data

We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in the Hubble Space Telescope/Cosmic Origins Spectrograph spectra, both during the campaign and in other epochs extending over 14 yr. We conclude that, while the narrow absorption outflow system (at −3750 km s−1 with FWHM = 177 km s−1) responds to the variations of the UV continuum as modified by the X-ray obscurer, its total column density (log N H = 19.5 −0.13+0.61 cm−2) did not change across all epochs. The adjusted ionization parameter (scaled with respect to the variations in the hydrogen-ionizing continuum flux) is log U H = −1.0 −0.3+0.1 . The outflow is located at a distance smaller than 38 pc from the central source, which implies a hydrogen density of n H > 3000 cm−3. The absorption outflow system only covers the continuum emission source and not the broad emission line region, which suggests that its transverse size is small (< 1016 cm), with potential cloud geometries ranging from spherical to elongated along the line of sight.

Connection between Emission and Absorption Outflows through the Study of Quasars with Extremely High Velocity Outflows

A recently discovered class of outflows, extremely high velocity outflows (EHVOs), may be key to understanding feedback processes, as it is likely the most powerful in terms of mass energy. These EHVOs have been observed at redshifts 1.052 < z em < 7.641, but the potential connection with outflows in emission has not been studied. We find that EHVOs, albeit their small numbers at the moment, appear to show distinct C iv and He ii properties. In particular, EHVOs are more predominant in quasars with large blueshifts of the C iv emission line, suggesting a connection between emission and absorption outflowing signatures for these extreme outflows. We also find incipient trends with the maximum velocity of the outflows, which is similar to what has been previously found in BALQSOs but now extending previous studies to speeds up to ∼0.2c. We find that the bolometric luminosities, Eddington ratios, and black hole masses of our sample are overall very similar to the general quasar population upon considering their C iv emission properties. This is close to the case for He ii EW, as we observe a tentative upper limit to the He ii strength for a quasar to host an EHVO. This study shows that extreme outflows such as EHVOs appear in quasars that are clearly a distinct class from the overall BALQSO population and solidify the relation between outflows observed in emission and absorption.

The Farthest Quasar Mini-Broad Absorption Line Outflow from Its Central Source: Very Large Telescope/UVES Observation of SDSS J0242+0049

Abstract We analyze Very Large Telescope/UVES observations of the quasar SDSS J024221.87+004912.6. We identify four absorption outflow systems: a C iv broad absorption line (BAL) at v ≈ −18,000 km s−1 and three narrower low-ionization systems with centroid velocities ranging from –1200 to –3500 km s−1. These outflows show similar physical attributes to the [O iii] outflows studied by Liu et al. (2013). We find that two of the systems are energetic enough to contribute to active galactic nucleus feedback, with one system reaching above 5% of the quasar’s Eddington luminosity. We also find that this system is at a distance of 67 kpc away from the quasar, the farthest detected mini-BAL absorption outflow from its central source to date. In addition, we examine the time-variability of the BAL and find that its velocity monotonically increases, while the trough itself becomes shallower over time.

The contribution of quasar absorption outflows to AGN feedback

ABSTRACT Determining the distance of quasar absorption outflows from the central source (R) and their kinetic luminosity ($\dot{E}_\mathrm{\scriptstyle k}$) is crucial for understanding their contribution to active galactic nucleus (AGN) feedback. Here, we summarize the results for a sample of nine luminous quasars that were observed with the Hubble Space Telescope. We find that the outflows in more than half of the objects are powerful enough to be the main agents for AGN feedback, and that most outflows are found at R &amp;gt; 100 pc. The sample is representative of the quasar absorption outflow population as a whole and is unbiased towards specific ranges of R and $\dot{E}_\mathrm{\scriptstyle k}$. Therefore, the analysis results can be extended to the majority of such objects, including broad absorption line quasars. We find that these results are consistent with those of another sample (seven quasars) that is also unbiased towards specific ranges of R and $\dot{E}_\mathrm{\scriptstyle k}$. Assuming that all quasars have absorption outflows, we conclude that most luminous quasars produce outflows that can contribute significantly to AGN feedback. We also discuss the criterion for whether an outflow is energetic enough to cause AGN feedback effects.

Evidence that emission and absorption outflows in quasars are related

ABSTRACT We analyse VLT/X-shooter data for seven quasars, where we study the relationships between their broad absorption line (BAL) and emission line outflows. We find (1) the luminosity of the [O iii] λ5007 emission profile decreases with increasing electron number density ($n_\mathrm{e}$) derived from the BAL outflow in the same quasar, (2) the measured velocity widths from the [O iii] emission features and C iv absorption troughs in the same object are similar, and (3) the mean radial velocity derived from the BAL outflow is moderately larger than the one from the [O iii] emission outflow. These findings are consistent with [O iii] and BAL outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution. When we have outflows with smaller distances to the central source, their $n_\mathrm{e}$ is higher. Therefore, the [O iii] emission is collisionally de-excited and the [O iii] luminosity is then suppressed. Comparisons to previous studies show that the objects in our sample exhibit broad [O iii] emission features similar to the ones in extremely red quasars (ERQs). This might imply that BAL quasars and ERQs have the same geometry of outflows or are at a similar evolutionary stage. We find that the physical parameters derived from the BAL outflows can explain the amount of observed [O iii] luminosity, which strengthens our claim that both BAL and [O iii] outflows are from the same wind. These estimates can be tested with upcoming James Webb Space Telescope, which will be able to spatially resolve some of the ionized gas outflows.

HST/COS Observations of Quasar Outflows in the 500–1050 Å Rest Frame. I. The Most Energetic Outflows in the Universe and Other Discoveries

The Hubble Space Telescope/Cosmic Origins Spectrograph (COS) has opened a new discovery space for studying quasar absorption outflows and their contribution to AGN feedback. Specifically, COS provides high-quality far-ultraviolet (FUV) spectra covering the diagnostic-rich 500-1050 Angstrom rest frame (hereafter, EUV500) of medium redshift objects. The quality and quantity of EUV500 diagnostic troughs allow us to probe the very high-ionization phase, which carries 90% or more of the outflowing material, as well as to determine the distance of most outflows from the central source ($R$). The first objective is impossible to achieve with ground-based spectra, and $R$ can be measured in only $\sim$1% of them. Here, we summarize the main results of the first dedicated survey of such outflows, including the following: 1) Measurements of the three most energetic outflows to date, which can be the main agents for AGN feedback processes in the environments of the host galaxies. 2) All the outflows have a very high-ionization component, similar to the one found in warm absorbers, which carries most of the outflow's kinetic luminosity. This finding suggests that all the high-ionization outflows observed from the ground also have a similar undetected very high-ionization component. 3) Of the 13 studied EUV500 outflows, 9 have $100<R<2000$ parsecs, 2 have $5<R<20$ parsecs, 1 has $0.05<R<50$ parsecs, and in 1 case, $R$ cannot be determined. 4) One of the outflows has the largest velocity shift (1550 km s$^{-1}$) and acceleration (1.5 cm s$^{-2}$) measured to date. This outflow is physically similar to the fast X-ray outflow detected in quasar PG 1211+143.

Distance, Energy, and Variability of Quasar Outflows: Two HST/COS Epochs of LBQS 1206+1052∗

Abstract We analyze new HST/COS spectra for two quasar absorption outflows seen in the quasi-stellar object LBQS 1206+1052. These data cover, for the first time, absorption troughs from S iv, Si ii, and P v. From the ratio of the S iv* to S iv column densities, we measure the electron number density of the higher-velocity (−1400 km s−1, v1400) outflow to be cm−3 and constrain the lower-velocity (−730 km s−1, v700) outflow to log(n e ) &gt; 5.3 cm−3. The n e associated with the higher-velocity outflow is an order of magnitude larger than reported in prior work. We find that the previous measurement was unreliable since it was based on density-sensitive absorption troughs that were likely saturated. Using photoionization models, we determine the best χ 2-minimization fit for the ionization parameter and hydrogen column density of the higher-velocity outflow: log( and log( cm−2, respectively. We calculate from U H and n e a distance of pc from the central source to the outflow. Using an SED attenuated by the v700 outflow yields a two-phase photoionization solution for the v1400 outflow, separated by a . Otherwise, the resultant distance, mass flux, and kinetic luminosity are similar to the unattenuated case. However, the attenuated analysis has significant uncertainties due to a lack of constraints on the v700 outflow in 2017.

Evidence that 50% of BALQSO Outflows Are Situated at Least 100 pc from the Central Source

Abstract The most robust way for determining the distance of quasar absorption outflows is the use of troughs from ionic excited states. The column density ratio between the excited and resonance states yields the outflow number density. Combined with a knowledge of the outflow’s ionization parameter, a distance from the central source (R) can be determined. Here we report results from two surveys targeting outflows that show troughs from S iv. One survey includes 1091 SDSS and BOSS quasar spectra, and the other includes higher-quality spectra of 13 quasars observed with the Very Large Telescope. Our S iv samples include 38 broad absorption line (BAL) outflows and four mini-BAL outflows. The S iv is formed in the same physical region of the outflow as the canonical outflow-identifying species C iv. Our results show that S iv absorption is only detected in 25% of C iv BAL outflows. The smaller detection fraction is due to the higher total column density (N H) needed to detect S iv absorption. Since R empirically anticorrelates with N H, the results of these surveys can be extrapolated to C iv quasar outflows with lower N H as well. We find that at least 50% of quasar outflows are at distances larger than 100 pc from the central source, and at least 12% are at distances larger than 1000 pc. These results have profound implications for the study of the origin and acceleration mechanism of quasar outflows and their effects on the host galaxy.

Leaked Lyα Emission: An Indicator of the Size of Quasar Absorption Outflows

Abstract The galactocentric distance of quasar absorption outflows are conventionally determined using absorption troughs from excited states, a method hindered by severely saturated or self-blended absorption troughs. We propose a novel method to estimate the size of a broad absorption line (BAL) region, which partly obscures an emission line region by assuming virialized gas in the emission region surrounding a supermassive black hole with known mass. When a spiky Lyα line emission is present at the flat bottom of the deep N v absorption trough, the size of the BAL region can be estimated. We have found three BAL quasars in the SDSS database showing such Lyα lines. The scale of their BAL outflows are found to be 3–26 pc, moderately larger than the theoretical scale (0.01–0.1 pc) of trough forming regions for winds originating from accretion disks, but significantly smaller than most outflow sizes derived using the absorption troughs of the excited states of ions. For these three outflows, the lower limits of the ratio of kinetic luminosity to Eddington luminosity are 0.02%–0.07%. These lower limits are substantially smaller than that required to have a significant feedback effect on their host galaxies.

Outflow in Overlooked Luminous Quasar: Subaru Observations of AKARI J1757$+$5907

Abstract We present Subaru observations of the newly discovered luminous quasar AKARI J1757$+$5907, which shows an absorption outflow in its spectrum. The absorption consists of 9 distinct troughs, and our analysis focuses on the troughs at $\sim-$1000 km s$^{-1}$ for which we could measure accurate column densities of He I$^*$, Fe II, and Mg II. We used photoionization models to constrain the ionization parameter, total hydrogen column density, and number density of the outflowing gas. These constraints yielded lower limits for the distance, mass-flow rate, and kinetic luminosity for outflows of 3.7 kpc, 70 $M_{\odot}$ yr$^{-1}$, and 2.0 $\times$10$^{43}$ erg s$^{-1}$, respectively. Such a mass-flow rate value can contribute significantly to metal enrichment of the intra-cluster medium. We found that this moderate velocity outflow is similar to those recently discovered in massive post-starburst galaxies. Finally, we describe the scientific potential of future observations targeting this object.

Improved redshifts for SDSS quasar spectra

A systematic investigation of the relationship between different redshift estimation schemes for more than 91000 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 6 (DR6) is presented. The publicly available SDSS quasar redshifts are shown to possess systematic biases of Dz/(1+z)>=0.002 (600km/s) over both small (dz~0.1) and large (dz~1) redshift intervals. Empirical relationships between redshifts based on i) CaII H & K host galaxy absorption, ii) quasar [OII] 3728, iii) [OIII] 4960,5008 emission, and iv) cross-correlation (with a master quasar template) that includes, at increasing quasar redshift, the prominent MgII 2799, CIII] 1908 and CIV 1549 emission lines, are established as a function of quasar redshift and luminosity. New redshifts in the resulting catalogue possess systematic biases a factor of ~20 lower compared to the SDSS redshift values; systematic effects are reduced to the level of Dz/(1+z)<10^-4 (30km/s) per unit redshift, or <2.5x10^-5 per unit absolute magnitude. Redshift errors, including components due both to internal reproducibility and the intrinsic quasar-to-quasar variation among the population, are available for all quasars in the catalogue. The improved redshifts and their associated errors have wide applicability in areas such as quasar absorption outflows, quasar clustering, quasar-galaxy clustering and proximity-effect determinations.

Broad Absorption Line Quasars and the Radio‐Loud/Radio‐Quiet Dichotomy

ABSTRACTThe observation that the extremely broad, blueshifted absorption troughs which characterize broad absorption line quasars (BALQs) occur exclusively in radio‐quiet quasars (RQQs) suggests that this class of active galactic nuclei (AGN) may offer important clues to the radio‐loud/radio‐quiet (RL/RQ) dichotomy in quasars. Interestingly, there is also substantial observational evidence for similar, but lower velocity, intrinsic absorption outflows in some Seyfert galaxies and radio‐loud quasars (RLQs) as well. Theoretically, however, it is difficult to interpret this broad range of mass ejection phenomena in the context of the standard model for BALQs. Thus, a new model is considered here in which the thermal gas producing the blueshifted absorption troughs is associated with a poorly collimated outflow of weakly radio‐emitting plasma—in essence, a weak jet. This model provides an appropriate framework not only for assessing the possible connection between the BAL phenomenon in RQQs and related intrinsic absorption outflows in stronger radio sources and in less luminous sources, both of which are known to possess jetlike radio structure, but also for understanding the RL/RQ dichotomy in light of recent observations which indicate that at least some RQQs possess central engines that are capable of producing weak versions of the powerful radio jets characteristic of RLQs. In the context of a weak jet model for BALQs, it is shown that observational constraints on the physical properties of the radio‐emitting plasma are consistent with other theoretical arguments suggesting that the differences amongst RL and RQ sources can be attributed to jets with intrinsically different physical properties. Similarly, theoretical constraints on the physical properties of absorbing clouds embedded in weak jets are shown to be consistent with the properties directly inferred from the observed BAL troughs. Most importantly, however, it is argued that a weak jet model provides a successful explanation for the anticorrelation between the terminal velocity of the absorption outflow and the radio power of the quasar.

In vitro techniques for modelling rumen transformation and syntheses

Abstract There are two major ways to model the microbial activity in the rumen. The first is the material or physical modelling with in vitro systems and the other is mathematical modelling with sets of equations.The evaluation of the ability of in vitro devices is to mimic in vivo ruminal digestion needs to perform first a typology of the most known and published in vitro procedures. This typology is aimed at clustering them according to their basic function (batch or continuous), to their major targets (studies of food degradation, of microbial proteosynthesis, of volatile fatty acid (VFA) production and profile, of gas production and composition, of outflow influences, of interactions between microbe species … also of prediction of intake of food nutritive value), to their level of time integration (cumulative at a given time or kinetic values), to their actual validity to simulate one or several items of ruminal digestion. Another key of typology of in vitro procedures is also the nature of the active substance, microbes or enzymes.Rumen mathematical modelling can be variously used in connection with in vitro and in vivo experimentations. At least three main targets can be pursued in this perspective:To model in vivo ruminal digestion. This aspect already has a long history because the first actual mechanistic model of whole rumen digestion was that of Baldwin et al. (1970). Since this date around a tenth of whole rumen models were proposed. Their current limits are those of the knowledge on rumen digestion: proteosynthesis, VFA production, nutrient absorption, liquid and particle outflows. As far as we are aware, none of these published rumen models was checked against in vitro data. One reason could be that some of them were more or less built from in vitro data.To model in vitro devices. Surprisingly no such specific model seemed to be published until now. In our opinion it is urgent to develop such models because they could be highly useful: to compare analogies and discrepancies between the various in vitro procedures; to try to build a unique model of in vitro ruminal digestion which could be parameterized according to the type of device; to elucidate intrinsic properties of micro-organisms.To model both in vitro and in vivo digestion. This way is likely to be the most difficult but it is also potentially the most fruitful. Effectively the use of an intermediate mathematical model of the rumen seems to be a priori the best way to check the major areas of analogy and discrepancy between in vivo and in vitro events. Thus this approach could be an objective mean of validation of in vitro studies.