We studied AGN activity in twelve LSSs in the ORELSE survey, at 0.65<z<1.28, using a combination of Chandra observations, optical and NIR imaging and spectroscopy. We located a total of 61 AGNs across our sample that were successfully matched to optical counterparts in the LSSs. Seeking to study AGN triggering mechanisms, we examined the spatial distribution of the AGNs and their average spectral properties. We found that AGN populations across our sample had less time since the last starburst than the overall galaxy populations. We did not find any relation between AGN activity and location within the LSSs, suggesting triggering mechanisms which depend on global environment are at most sub-dominant. To focus on differences between our AGNs, we grouped them into four sub-samples based on the spectral properties of their parents LSSs. We found one of the sub-samples, SG0023 & SC1604, stood out from the others: AGNs in this sample were disproportionately luminous, their average time since the last starburst event was the smallest, despite the fact that this was not true of the overall galaxy population in those LSSs, and both the AGNs and the overall galaxy population had the largest fraction of close kinematic pairs, which indicates a higher rate of galaxy mergers and interactions. These results suggest that major mergers are driving AGN activity in SG0023 & SC1604, while other processes are likely triggering less luminous AGNs in the rest of our sample. Additionally, minor mergers are unlikely to play a significant role, since the same conditions that lead to more major mergers should should also lead to more minor mergers, which is not observed in SG0023 & SC1604.
Recent hydrodynamic simulations and observations of radio jets have shown that the surrounding environment has a large effect on their resulting morphology. To investigate this we use a sample of 50 Extended Radio Active Galactic Nuclei (ERAGN) detected in the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey. These sources are all successfully cross-identified to galaxies within a redshift range of $0.55 \leq z \leq 1.35$, either through spectroscopic redshifts or accurate photometric redshifts. We find that ERAGN are more compact in high-density environments than…
Radio Active Galactic Nuclei (RAGNs) are mainly found in dense structures (i.e., clusters/groups) at redshifts of z$<$2 and are commonly used to detect protoclusters at higher redshift. Here, we attempt to study the host and environmental properties of two relatively faint ($\mathrm L_\mathrm{1.4GHz} \sim10^{25}$ W Hz$^{-1}$) RAGNs in a known protocluster at z=3.3 in the PCl J0227-0421 field, detected using the latest radio observation obtained as part of the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey. Using new spectroscopic observations obtained from Keck/…
The FeII emission in active galactic nuclei: excitation mechanisms and location of the emitting region
我们提出了一个研究FeII发射在近红外区域（NIR）的25个活动星系核（AGN），以获得有关的激励机制，它的权力和它的形成位置的信息。我们采用了近红外FeII模板来自文献中，发现它成功地再现了所观察到的FeII光谱。在所研究的所有物体中检测到的9200埃的FeII碰撞证实了活动星系核中总是存在莱曼α荧光。9200埃凸点的通量、1微米线和光学Fe II之间的相关性表明，莱曼α荧光在Fe II的产生中起着重要作用。我们确定至少18%的光学FeII是由于这个过程，而碰撞激发在观察到的FeII的产生中占主导地位。比较Fe II 10502、OI 11287、Ca II 8664和Paschen-beta的谱线轮廓，以收集关于它们最可能发射的位置的信息。我们发现，FeII，OI和CaII具有相似的宽度，平均比Paschen-beta窄30%。假设发射线的云是维里化的，我们表明，FeII是在一个区域的两倍远的中央源比Paschen-beta。距离变化很大：从NGC 4051的8.5光日到Mrk 509的198.2光日。我们的研究结果加强了FeII在NIR中的重要性，以限制驱动其物理和基本活动星系核运动学的关键参数，以及旨在再现这种复杂发射的更准确的模型。
Basing our analysis on ROGUE I, a catalog of over 32,000 radio sources associated with optical galaxies, we provide two diagnostics to select the galaxies where the radio emission is due to an active galactic nucleus (AGN). Each of these diagnostics can be applied independently. The first one, dubbed MIRAD, compares the flux $F_{W3}$ in the $W3$ mid-infrared band of the WISE telescope, with the radio flux at 1.4 GHz, $\Frad$. MIRAD requires no optical spectra. The second diagnostic, dubbed DLM, relates the 4000 Å break strength, $D_{\rm n}(4000)$, with the radio luminosity per unit stellar mas…
Simulating X-ray Reverberation in the UV-Emitting Regions of Active Galactic Nuclei Accretion Disks with 3D Multi-Frequency Magnetohydrodynamic Simulations
The discovery of $γ$-ray emission from some radio-loud narrow-line Seyfert 1 galaxies (RLNLS1s) indicated the presence of a relativistic beamed jet in these objects. This immediately opened a new question about their parent population: is how do they look like when observed at large angles? The study of the parent population has provided important new insights on the physical properties of this fascinating class of active galactic nuclei (AGN). In this work, I will review the most recent advances in the study of parent sources, and I will show the impact that a recent continuum survey carried …
We investigate the structure of the Mg II broad line emission region in a sample of 284 Type 1 active galactic nuclei (AGNs), through comparing the kinematical parameters of the broad Mg II and broad H$β$ lines. We found that the Mg II emitting region has more complex kinematics than the H$β$ one. It seems that the \ion{Mg}{ii} broad line originates from two subregions: one which contributes to the line core, which is probably virialized, and the other, 'fountain-like' emitting region, with outflows-inflows nearly orthogonal to the disc, which become suppressed with stronger gravitational infl…
Tracing the Energetic Outflows from Galactic Nuclei: Observational Evidence for a Large-Scale Bipolar Radio and X-ray-emitting Bubble-like Structure in M106
In the hierarchical structure formation model, galaxies grow through various merging events. Numerical simulations indicate that the mergers can enhance the activity of the central supermassive black holes in the galaxies. Pfeifle et al. (2019a) identified a system of three interacting galaxies, J0849$+$1114, and provided multiwavelength evidence of all three galaxies containing active galactic nuclei. The system has substantial radio emission, and with high-resolution radio interferometric observation we aimed to investigate its origin, whether it is related to star formation or to one or mor…
Using 57 Radio Active Galactic nuclei (RAGN) at 0.55 $\leq$ z $\leq$ 1.3 drawn from five fields of the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey, we study the effect of injection of energy from outbursts of RAGN on their spectroscopically-confirmed neighboring galaxies (SNGs). We observe an elevated fraction of quenched neighbors (fq) within 500 kpc projected radius of RAGN in the most dense local environments compared to those of non-RAGN control samples matched to the RAGN population in colour, stellar mass, and local environment at 2$σ$ significance. Fur…
Reverberation mapping (RM) is a widely-used method for probing the physics of broad-line regions (BLRs) in active galactic nuclei (AGNs). There are increasing preliminary evidences that the RM behaviors of broad emission lines are influenced by BLR densities, however, the influences have not been investigated systematically from theoretical perspective. In the present paper, we adopt locally optimally emitting cloud model and use CLOUDY to obtain the one-dimensional transfer functions of the prominent UV and optical emission lines for different BLR densities. We find that the influences of BLR…
Mapping the nuclear environments of extreme coronal line emitting galaxies
University of Portsmouth（朴茨茅斯大学）；American Museum of Natural History（美国自然历史博物馆）；University of Southampton（南安普顿大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）；Università degli Studi di Milano（米兰大学）；INAF-Osservatorio Astronomico di Brera（INAF-布雷拉天文台）；University College London（伦敦大学学院）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）
Constraining UV Continuum Slopes of Active Galactic Nuclei With CLOUDY Models of Broad Line Region EUV Emission Lines
了解活动星系核（AGN）宽线区（BLR）的组成和结构对于解答超大质量黑洞演化、星系演化和星系际介质电离等许多悬而未决的问题具有重要意义。我们使用哈勃太空望远镜上的宇宙起源摄谱仪（COS）的单历元紫外光谱，测量了四个单独的活动星系核与$0.49 \le z \le 0.64$，两个活动星系核与$0.32 \le z \le 0.40$，和159个活动星系核的复合物的EUV发射线通量。用云光电离程序计算了BLR云的发射线通量，并给出了不同密度、氢电离通量和入射连续谱指数的BLR云的发射线通量。使用单组分和局部最佳发射云（ORFO）模型将光电离网格拟合到观测结果。双组分模型能很好地拟合实测通量，而单组分模型则不能。紫外光谱指数的首选我们的COMS模型是一致的COS光谱测量。EUV发射线，例如N IV λ765、O II λ833和O III λ834，主要源自电子温度在37000 K和55000 K之间的气体。这种气体存在于具有高氢密度（n_H \ge 10^12 cm^-3）和氢电离光子通量（Φ_H \ge 10^22 cm^-2 s^-1）的BLR云中。
Broad Emission Lines are the most characteristic features of Active Galaxies, but the mechanism of creating a medium able to emit these intense lines is not quite clear. Observations clearly indicate that the motion of the material is predominantly Keplerian, with traces of inflow and clear signatures of outflow, but this still does not point out whether the lines partially come from the disk surface, or exclusively from the circumnuclear material, and whether this material originates from the disk as a wind, or comes, at least partially, from outside. I review the basic scenarios for the form…
This article reviews our current understanding about $γ$-ray detected narrow-line Seyfert 1 ($γ$-NLSy1) galaxies. The detection with the Large Area Telescope onboard {\it Fermi}~Gamma-ray Space Telescope has provided the strongest evidence for the presence of closely aligned relativistic jet in these intriguing active galactic nuclei (AGN) and opened up a realm to explore the physical conditions needed to launch the jet in a different central engine and host galaxy environment than that is known for blazars. Promising results acquired from various multi-wavelength campaigns are converging to a…
Lyman continuum and line emission are thought to be important agents in the reionization of the early universe. Haro 11 is a rare example of a local galaxy in which Ly$α$ and continuum emission have escaped without being absorbed or scattered by ambient gas and dust, potentially as a consequence of feedback from its X-ray sources. We build on our previous Chandra analysis of Haro 11 by analyzing three new observations. Our subpixel spatial analysis reveals that the two previously known X-ray sources are each better modelled as ensembles of at least 2 unresolved point sources. The spatial varia…
One of the major challenges in studying the cosmic evolution of relativistic jets is the identification of the high-redshift ($z>3$) BL Lacertae objects, a class of jetted active galactic nuclei characterized by their quasi-featureless optical spectra. Here we report the identification of the first $γ$-ray emitting BL Lac object, 4FGL~J1219.0+3653 (J1219), beyond $z=3$, i.e., within the first two billion years of the age of the Universe. The optical and near-infrared spectra of J1219 taken from 10.4 m Gran Telescopio Canarias exhibit no emission lines down to an equivalent width of $\sim$3.5 A…
Active Galactic Nuclei (AGN) are remarkable astronomical sources emitting over the whole electromagnetic spectrum, with different bands providing unique windows on distinct sub-structures and their related physics. AGN come in a large number of types only partially related to intrinsic differences. I highlight here the most important AGN classes, namely jetted and non-jetted, radiatively efficient and inefficient, and face-on and edge-on, the source types selected by different bands together with the most important selection effects and biases, and the underlying emission processes, emphasisin…
In this study we investigate 179 radio-IR galaxies drawn from a sample of spectroscopically-confirmed galaxies that are detected in radio and mid-infrared (MIR) in the redshift range of $0.55 \leq z \leq 1.30$ in the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey. We constrain the Active Galactic Nuclei (AGN) contribution in the total IR luminosity (f$_{\text{AGN}}$), and estimate the AGN luminosity (L$_{\text{AGN}}$) and the star formation rate (SFR) using the CIGALE Spectral Energy Distribution (SED) fitting routine. Based on the f$_{\text{AGN}}$ and radio lum…
The line parameters and ratios as the physical probe of the line emitting regions in AGN
本文讨论了活动星系核（AGN）发射线区（ELR）的物理条件，特别强调了尚未解决的问题，如宽线区（BLR）的分层或光电离不能解释观测到的强光学Fe II发射。在这里，我们使用不同的线通量，以探测ELR的属性，如氢巴耳末线（Ha到He），氦线从两个随后的电离水平（He II 4686和He I 5876）和最强的Fe II线在波长范围4400-5400 nm。我们发现，氢巴耳末和氦线可以用于估计的物理参数的BLR，我们表明，Fe II发射主要是从中间线区域（ILR），这是位于更远离中央连续源比BLR。
The central engines of Active Galactic Nuclei (AGNs) are powered by accreting supermassive black holes, and while AGNs are known to play an important role in galaxy evolution, the key physical processes occur on scales that are too small to be resolved spatially (aside from a few exceptional cases). Reverberation mapping is a powerful technique that overcomes this limitation by using echoes of light to determine the geometry and kinematics of the central regions. Variable ionizing radiation from close to the black hole drives correlated variability in surrounding gas/dust, but with a time dela…
The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of gamma-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum radio quasars (FSRQs), their gamma-ray emission is thought to be produced via the external Compton mechanism whereby relativistic jet electrons upscatter a photon field external to the jet, e.g. from the accretion disc, broad line region (BLR) and dusty torus, to higher energies. Here we study the origin of the gamma-ray emission in the lowest-redsh…
What triggers collimated relativistic outflows or jets, from the centers of galaxies remains a fundamental question in astrophysics. The merging of two galaxies has been proposed to realize the conditions to successfully launch and drive such jets into the intergalactic medium. However, evidences for the operation of this mechanism are scarce. Here we report the first unambiguous detection of an ongoing merger of a narrow-line Seyfert 1 galaxy, TXS 2116$-$077, hosting a closely aligned, $γ$-ray emitting relativistic jet with a Seyfert 2 galaxy at a separation of $\sim$12 kpc, using the observa…
A long standing problem in the study of Active Galactic Nuclei (AGNs) is that the observed VLBI core is in fact a blending of the actual AGN core (classically defined by the $τ=1$ surface) and the upstream regions of the jet or optically thin emitting region flows. This blending may cause some biases towards the observables of the core, such as its flux density, size or brightness temperature, which may lead to misleading interpretation of the derived quantities and physics. We study the effects of such blending under the view of the Korean VLBI Network (KVN) for a sample of AGNs at 43 GHz by …
The narrow-line Seyfert 1 (NLS1) galaxy PMN J0948+0022 is an archetype of gamma-ray-emitting NLS1s in active galactic nuclei (AGNs). In this study, we investigate its radio structures using archival data obtained using the Karl G.~Jansky very large array (VLA) and the very long baseline array (VLBA). The new VLA images reveal an outermost radio emission separated by 9.1 arcsec. Its resolved structure and steep spectrum suggest a terminal shock in a radio lobe energized by the jet from the PMN J0948+0022 nucleus. This large-scale radio component is found at almost the same position angle as tha…
In this paper, transient high energy events and their hosts are discussed with focus on signatures of radio synchrotron emission. Outstanding questions range from the origin of the two phases of radio emission in supernovae to the formation of conical jets launched at relativistic velocities in active nuclei to the formation of radio hotspots in FR II sources to the formation of radio relics and halos in clusters of galaxies to the origin of the relativistic electron population and its energy spectrum which is responsible for the synchrotron emission to the composition of the radio synchrotron…
POLAMI: Polarimetric Monitoring of Active Galactic Nuclei at Millimetre Wavelengths. III. Characterisation of total flux density and polarisation variability of relativistic jets
The apparent position of jet base (core) in radio-loud active galactic nuclei changes with frequency because of synchrotron self-absorption. Studying this `core shift` effect enables us to reconstruct properties of the jet regions close to the central engine. We report here results from core shift measurements in AGNs observed with global VLBI at 2 and 8 GHz at epochs from 1994 to 2016. Our sample contains 40 objects observed at least 10 times during that period. The core shift is determined using a new automatic procedure introduced to minimize possible biases. The resulting multiple epoch me…
Coronal-Line Forest AGN: the best view of the inner edge of the AGN torus?
我们介绍冕线森林活动星系核（CLiF AGN），AGN具有丰富的禁止高电离线（FHILs，例如[FeVII]，[FeX]和[NeV]），以及相对较强的窄（$\sim$ 300 km s $^{-1}$）H $α$发射相比，其他巴耳末过渡线。我们发现，CLiF发射区的运动学是类似的禁戒低电离发射线（FLIL）区域。我们将FHIL和FLIL的发射线强度与CLOUDY光电离结果进行比较，发现当与FLIL发射区（10 $^{3.0}$ $<$ n $_H$ $<$ 10 $^{7.5}$ cm $^{-3}$）相比时，CLiF发射区具有更高的密度（10 $^{4.5}$ $<$ n $_H$ $<$ 10 cm $^{-3}$）。我们使用光电离的结果来计算CLiF区域的径向距离（0.04 $<$ R $_{CLiF}$ $<$ 32.5 pc），并发现它们是可比的尘埃颗粒升华距离（0.10 $<$ R $_{SUB}$ $<$ 4.3 pc）。因此，我们认为，内环面壁是最有可能的位置的CLiF区域，和不寻常的强度的FHILs是由于一个特定的视角给出了一个最大的视图的远壁的环面没有连续被发现。
Ultraviolet (UV) line driven winds may be an important part of the active galactic nucleus (AGN) feedback process, but understanding their impact is hindered by the complex nature of the radiation hydrodynamics. Instead, we have taken the approach pioneered by Risaliti & Elvis, calculating only ballistic trajectories from radiation forces and gravity, but neglecting gas pressure. We have completely re-written their QWIND code using more robust algorithms, and can now quickly model the acceleration phase of these winds for any AGN spectral energy distribution spanning UV and X-ray wavebands. We…
