Studies investigating the relationship between AGN power and the star formation rates (SFRs) of their host galaxies often rely on averaging techniques -- such as stacking -- to incorporate information from non-detections. However, averages, and especially means, can be strongly affected by outliers and can therefore give a misleading indication of the "typical" case. Recently, a number of studies have taken a step further by binning their sample in terms of AGN power (approximated by the 2-10keV luminosity of the AGN), and investigating how the SFR distribution differs between these bins. These bin thresholds are often weakly motivated, and binning implicitly assumes that sources within the same bin have similar (or even identical) properties. In this paper, we investigate whether the distribution of host SFRs -- relative to the locus of the star-forming main sequence (i.e., $R_{\rm MS}$) -- changes continuously as a function of AGN power. We achieve this by using a hierarchical Bayesian model that completely removes the need to bin in AGN power. In doing so, we find strong evidence that the $R_{\rm MS}$ distribution changes with 2-10keV X-ray luminosity. The results suggest that higher X_ray luminosity AGNs have a tighter physical connection to the star-forming process than lower X-ray luminosity AGNs, at least within the $0.8 < z < 1.2$ redshift range considered here.
Offset active galactic nuclei (AGNs) are AGNs that are in ongoing galaxy mergers, which produce kinematic offsets in the AGNs relative to their host galaxies. Offset AGNs are also close relatives of dual AGNs. We conduct a systematic search for offset AGNs in the Sloan Digital Sky Survey, by selecting AGN emission lines that exhibit statistically significant line-of-sight velocity offsets relative to systemic. From a parent sample of 18314 Type 2 AGNs at z<0.21, we identify 351 offset AGN candidates with velocity offsets of 50 km/s < |v| < 410 km/s. When we account for projection effects in th…
Galaxy mergers are likely to play a role in triggering active galactic nuclei (AGN), but the conditions under which this process occurs are poorly understood. In Paper I, we constructed a sample of spatially offset X-ray AGN that represent galaxy mergers hosting a single AGN. In this paper, we use our offset AGN sample to constrain the parameters that affect AGN observability in galaxy mergers. We also construct dual AGN samples with similar selection properties for comparison. We find that the offset AGN fraction shows no evidence for a dependence on AGN luminosity, while the dual AGN fractio…
In the last few years, it became possible to observationally resolve galaxies with two distinct nuclei in their centre. For separations smaller than 10kpc, dual and offset active galactic nuclei (AGN) are distinguished: in dual AGN, both nuclei are active, whereas in offset AGN only one nucleus is active. To study the origin of such AGN pairs, we employ a cosmological, hydrodynamic simulation with a large volume of (182Mpc)^3 from the set of Magneticum Pathfinder Simulations. The simulation self-consistently produces 35 resolved black hole (BH) pairs at redshift z=2, with a comoving distance s…
Prompted by a recent claim by Barrows et al. that X-ray AGN are often found significantly offset from the centres of their host galaxies, we have looked for examples of compact radio sources which are offset from the optical centroids of nearby (z < 0.2) galaxies. We have selected a sample of 345 galaxies from the Sloan Digital Sky Survey (SDSS) galaxy catalog which have nearby compact radio sources listed in the Cosmic-Lens All Sky Survey (CLASS) catalog. We find only three matches (0.87 per cent of the sample) with offsets greater than 600 milliarcsec (mas), which is considerably fewer than …
We examine the dual (both BHs active) and offset (one BH active) AGN population (comprising $\sim$ 2000 pairs at $0.5\,\text{kpc}\lesssimΔr<30\,\text{kpc}$) at $z=2\sim3$ in the ASTRID simulation covering (360 cMpc)${^3}$. The dual (offset) AGN make up $3.0(2.2)\%$ of all AGN at $z=2$. The dual fraction is roughly constant while the offset fraction increases by a factor of ten from $z=4\sim2$. Compared with the full AGN population, duals are characterized by a low $M_\text{BH}/M_*$ ratio, a high specific star-formation rate (sSFR) of $\sim 1\,\text{Gyr}^{-1}$, and a high Eddington ratio ($\sim…
During galaxy mergers, gas and dust is driven towards the centers of merging galaxies, triggering enhanced star formation and supermassive black hole (SMBH) growth. Theory predicts that this heightened activity peaks at SMBH separations $<$20 kpc; if sufficient material accretes onto one or both of the SMBHs for them to become observable as active galactic nuclei (AGNs) during this phase, they are known as offset and dual AGNs, respectively. To better study these systems, we have built the ACS-AGN Merger Catalog, a large catalog ($N=220$) of uniformly selected offset and dual AGN observed by $…
While 2% of active galactic nuclei (AGNs) exhibit narrow emission lines with line-of-sight velocities that are significantly offset from the velocity of the host galaxy's stars, the nature of these velocity offsets is unknown. We investigate this question with Chandra/ACIS and Hubble Space Telescope/Wide Field Camera 3 observations of seven velocity-offset AGNs at z<0.12, and all seven galaxies have a central AGN but a peak in emission that is spatially offset by < kpc from the host galaxy's stellar centroid. These spatial offsets are responsible for the observed velocity offsets and are due t…
Gravitational-wave (GW) and gravitational slingshot recoil kicks, which are natural products of SMBH evolution in merging galaxies, can produce active galactic "nuclei" that are offset from the centers of their host galaxies. Detections of offset AGN would provide key constraints on SMBH binary mass and spin evolution and on GW event rates. Although numerous offset AGN candidates have been identified, none have been definitively confirmed. The ngVLA offers unparalleled capabilities to identify and confirm candidate offset AGN from sub-parsec to kiloparsec scales, opening a new avenue for multi…
Gravitational wave (GW) and gravitational slingshot recoil kicks, which are natural products of SMBH evolution in merging galaxies, can produce active galactic "nuclei" that are offset from the centers of their host galaxies. Detections of offset AGN would provide key constraints on SMBH binary mass and spin evolution and on GW event rates. Although numerous offset AGN candidates have been identified, none have been definitively confirmed. Multi-wavelength observations with next-generation telescopes, including systematic large-area surveys, will provide unprecedented opportunities to identify…
We present a sample of 18 optically-selected and X-ray detected spatially offset active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS). In 9 systems, the X-ray AGN is spatially offset from the galactic stellar core that is located within the 3'' diameter SDSS spectroscopic fiber. In 11 systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of 2. To build the sample, we cross-matched Type II AGN selected from the SDSS galaxy catalogue with archival Chandra imaging and employed our custom astrometric and registration proc…
Significant positional offsets of the value from 1 mas to more than 10 mas were found previously between radio (VLBI) and optical (Gaia) positions of active galactic nuclei (AGN). They happen preferentially parallel to the parsec-scale jet direction. AGN with VLBI-to-Gaia offsets pointed downstream the jet are found to have favourably higher optical polarization, as expected if extended optical jets dominate in the emission and shift the Gaia centroid away from the physical nucleus of the source. Upstream offsets with the suggested domination of accretion disks manifest themselves through the …
Galaxy pairs with separations of only a few kpc represent important stages in the merger-driven growth of supermassive black holes (SMBHs). However, such mergers are difficult to identify observationally due to the correspondingly small angular scales. In Paper I we presented a method of finding candidate kpc-scale galaxy mergers that is leveraged on the selection of X-ray sources spatially offset from the centers of host galaxies. In this paper we analyze new Hubble Space Telescope (HST) WFC3 imaging for six of these sources to search for signatures of galaxy mergers. The HST imaging reveals …
We report the detection of an intriguing parsec-scale radio source in the "offset AGN" candidate, KISSR 102. The elliptical host galaxy includes two optical nuclei at a projected separation of 1.54 kpc, N1 and N2, to the south-east and north-west, respectively. Phase-referenced VLBA observations at 1.5 and 4.9 GHz of this LINER galaxy, have detected double radio components (A and B) at a projected separation of 4.8 parsec at 1.5 GHz, and another partially-resolved double radio structure at 4.9 GHz coincident with the brighter radio component A. These radio detections are confined to the optica…
The gravitational waves from Massive black-hole (MBH) binaries are expected to be detected by pulsar timing arrays in the next few years. While they are a promising source for multimessenger observations as binary AGN, few convincing candidates have been identified in electromagnetic surveys. One approach to identifying candidates has been through spectroscopic surveys searching for offsets or time-dependent offsets of broad emission lines (BLs), which may be characteristic of Doppler shifts from binary orbital motion. In this study, we predict the parameter space of MBH binaries that should b…
We study the displacements between the centres of galaxies and their supermassive black holes (BHs) in the cosmological hydrodynamical simulation Horizon-AGN, and in a variety of observations from the literature. The BHs in Horizon-AGN feel a sub-grid dynamical friction force, sourced by the surrounding gas, which prevents recoiling BHs being ejected from the galaxy. We find that i) the fraction of spatially offset BHs increases with cosmic time, ii) BHs live on prograde orbits in the plane of the galaxy with an orbital radius that decays with time but stalls near $z=0$, and iii) the magnitude…
We have observed two kinematically offset active galactic nuclei (AGN), whose ionised gas is at a different line-of-sight velocity to their host galaxies, with the SAMI integral field spectrograph (IFS). One of the galaxies shows gas kinematics very different to the stellar kinematics, indicating a recent merger or accretion event. We demonstrate that the star formation associated with this event was triggered within the last 100 Myr. The other galaxy shows simple disc rotation in both gas and stellar kinematics, aligned with each other, but in the central region has signatures of an outflow d…
Using photometric variability information from the new Gaia DR3 release, I show for the first time that photometric variability is inversely correlated with the prevalence of optical-radio position offsets in the active galactic nuclei (AGNs) that comprise the International Celestial Reference Frame (ICRF). While the overall prevalence of statistically significant optical-radio position offsets is $11\%$, objects with the largest fractional variabilities exhibit an offset prevalence of only $\sim2\%$. These highly variable objects have redder optical color and steeper optical spectral indices …
We report the results of an investigation to determine the nature of the offset active galactic nucleus (AGN) found in the source CXO J101527.2+625911. Hubble Space Telescope and Chandra X-ray observatory data had suggested that the offset AGN, which has an angular separation of only 0\farcs26 from the center of the host galaxy, is a recoiled Super Massive Black Hole (rSMBH). We carried out high angular resolution observations with both the VLBA (1.54 GHz) and the VLA (10.0 GHz \& 33.0 GHz) and detected a single compact radio source in the center of the host galaxy, with no radio continuum emi…
We present a spectroscopic and imaging study of an abnormal active galactic nucleus (AGN), 2MASX J00423991+3017515. This AGN is newly identified in the hard X-rays by the Swift BAT All-Sky survey and found in an edge-on disk galaxy interacting with a nearby companion. Here, we analyze the first optical spectra obtained for this system (taken in 2011 and 2016), high-resolution imaging taken with the Hubble Space Telescope and Chandra X-ray Observatory, and 1" imaging with the Very Large Array. Two unique properties are revealed: the peaks of the broad Balmer emission lines (associated with gas …
A supermassive black hole (SMBH) ejected from the potential well of its host galaxy via gravitational wave recoil carries important information about the mass ratio and spin alignment of the pre-merger SMBH binary. Such a recoiling SMBH may be detectable as an active galactic nucleus (AGN) broad line region offset by up to 10\,kpc from a disturbed host galaxy. We describe a novel methodology using forward modeling with \texttt{The Tractor} to search for such offset AGN in a sample of 5493 optically variable AGN detected with the Zwicky Transient Facility (ZTF). We present the discovery of 9 AG…
The nearby galaxy NGC 3115 contains a known radio-emitting, low-luminosity active galactic nucleus (AGN), and was recently claimed to host a candidate AGN displaced 14.3 pc from the galaxy's optical photocenter. Our goal is to understand whether this represents a single offset AGN, an AGN in orbit around a central black hole, or something else. We present a new, sensitive (RMS = 4.4 $μ$Jy beam$^{-1}$) 10 GHz image, which finds evidence for only one AGN. We place a stringent limit on the radio luminosity of any secondary supermassive black hole of $L_{10~\rm{GHz}}<5.8\times10^{33}$ ergs/s. An a…
This paper presents a detection of significant velocity offset between emission and absorption lines for a dual core system in SDSS~J155708.82+273518.74 (= SDSS~J1557). The photometric image of SDSS~J1557 exhibits clear two cores with a projected separation of $\sim$2.2 arcseconds (4.9 kpc) determined by GALFIT. Based on the applications of the commonly accepted pPXF code with 636 theoretical SSP templates, the host galaxy contribution can be well determined. Then, the emission line features of SDSS~J1557 can be well measured after subtraction of host starlight. It is found that the velocity o…
We present spatially resolved Hubble Space Telescope grism spectroscopy of 15 galaxies at $z\sim0.8$ drawn from the DEEP2 survey. We analyze H$α$+[N II], [S II] and [S III] emission on kpc scales to explore which mechanisms are powering emission lines at high redshifts, testing which processes may be responsible for the well-known offset of high redshift galaxies from the $z\sim0$ locus in the [O III]/H$β$ versus [N II]/H$α$ BPT (Baldwin-Phillips-Terlevich) excitation diagram. We study spatially resolved emission line maps to examine evidence for active galactic nuclei (AGN), shocks, diffuse i…
Supermassive black hole (BH) mergers produce powerful gravitational wave (GW) emission. Asymmetry in this emission imparts a recoil kick to the merged BH, which can eject the BH from its host galaxy altogether. Recoiling BHs could be observed as offset active galactic nuclei (AGN). Several candidates have been identified, but systematic searches have been hampered by large uncertainties regarding their observability. By extracting merging BHs and host galaxy properties from the Illustris cosmological simulations, we have developed a comprehensive model for recoiling AGN. Here, for the first ti…
We present a multi-wavelength analysis of the galaxy cluster A1668, performed by means of new EVLA and Chandra observations and archival H$α$ data. The radio images exhibit a small central source ($\sim$14 kpc at 1.4 GHz) with L$_{\text{1.4 GHz}}$ $\sim$6 $\cdot$ 10$^{23}$ W Hz$^{-1}$. The mean spectral index between 1.4 GHz and 5 GHz is $\sim$ -1, consistent with the usual indices found in BCGs. The cooling region extends for 40 kpc, with bolometric X-ray luminosity L$_{\text{cool}} = 1.9\pm 0.1 \cdot$ 10$^{43}$ erg s$^{-1}$. We detect an offset of $\sim$ 6 kpc between the cluster BCG and the…
We present the ionized gas properties of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme optical/IR color, $(i - [22])_{\rm AB} > 7.0$, selected with the Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer (WISE). For 36 IR-bright DOGs that show [OIII]$λ$5007 emission in the SDSS spectra, we performed a detailed spectral analysis to investigate their ionized gas properties. In particular, we measured the velocity offset (the velocity with respect to the systemic velocity measured from the stellar absorption lines) and the velocity dispersion of the […
We analyze differences in positions of active galactic nuclei between Gaia data release 2 and VLBI and compare the significant VLBI-to-Gaia offsets in more than 1000 objects with their jet directions. Remarkably at least 3/4 of the significant offsets are confirmed to occur downstream or upstream the jet representing a genuine astrophysical effect. Introducing redshift and Gaia color into analysis can help distinguish between the contribution of the host galaxy, jet, and accretion disk emission. We find that strong optical jet emission at least 20-50pc long is required to explain the Gaia posi…
SDSS J150243.09+111557.3 is a merging system at z = 0.39 that hosts two confirmed AGN, one unobscured and one dust-obscured, offset by several kiloparsecs. Deane et al. recently reported evidence from the European VLBI Network (EVN) that the dust-obscured AGN exhibits two flat-spectrum radio sources, J1502SE/SW, offset by 26 mas (140 pc), with each source being energized by its own supermassive black hole (BH). This intriguing interpretation of a close binary BH was reached after ruling out a double-hotspot scenario, wherein both hotspots are energized by a single, central BH, a configuration …
Several recent papers have reported on the occurrence of active galactic nuclei (AGN) containing under-massive black holes relative to a linear scaling relation between black hole mass (M_bh) and host spheroid stellar mass (M_sph,*). Dramatic revisions to the M_bh-M_sph,* and M_bh-L_sph relations, based on samples containing predominantly inactive galaxies, have however recently identified a new steeper relation at M_bh < (2-10)x10^8 M_Sun, roughly corresponding to M_sph,* < (0.3-1)x10^{11} M_Sun. We show that this steeper, quadratic-like M_bh-M_sph,* relation defined by the Sersic galaxies, i…
We investigate a sample of 2293 ICRF2 extragalactic radio-loud sources with accurate positions determined by VLBI, mostly active galactic nuclei (AGN) and quasars, which are cross-matched with optical sources in the first Gaia release (Gaia DR1). The distribution of offsets between the VLBI sources and their optical counterparts is strongly non-Gaussian, with powerful wings extending beyond 1 arcsecond. Limiting our analysis to only high-confidence difference detections, we find (and publish) a list of 188 objects with normalized variances above 12 and offsets below 1 arcsecond. Pan-STARRS sta…
We present a combined radio/X-ray analysis of the poorly studied galaxy cluster Abell 2495 (z=0.07923) based on new EVLA and Chandra data. We also analyze and discuss Halpha emission and optical continuum data retrieved from the literature. We find an offset of 6 kpc between the cluster BCG (MCG+02-58-021) and the peak of the X-ray emission, suggesting that the cooling process is not taking place on the central galaxy nucleus. We propose that sloshing of the ICM could be responsible for this separation. Furthermore, we detect a second, 4 kpc offset between the peak of the Halpha emission and t…
Hunting Wandering 3<z<8 Black Holes: Spatial Offsets in Ionization Ratio and Continuum Emission
The University of Texas at Austin（德克萨斯大学奥斯汀分校）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；University of Connecticut（康涅狄格大学）；University of Kansas（堪萨斯大学）；The Pennsylvania State University（宾夕法尼亚州立大学）
Cosmic Pairs: A DESI Census of Dual and Offset AGN as Precursors to Massive Black Hole Binaries
Carnegie Mellon University（卡内基梅隆大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Institute for Advanced Study, Princeton（普林斯顿高等研究院）；Institute of Space Sciences, ICE-CSIC（空间科学研究所，西班牙国家科学研究委员会）；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚太空研究学院）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）
该研究基于 DESI DR1 光谱数据，构建了超大样本双与偏移 AGN，结合 ASTRID 模拟揭示其演化特征，为 LISA 可探测的大质量黑洞并合提供了前身星系群样本。
We present a comparative study of active galactic nuclei (AGN) between galaxy pairs and isolated galaxies with the final data release of the MaNGA integral field spectroscopic survey. We build a sample of 391 kinematic galaxy pairs within the footprint of the survey and select AGN using the survey's spectra. We use the comoving volume densities of the AGN samples to quantify the effects that tidal interactions have on the triggering of nuclear accretion. Our hypothesis is that the pair sample contains AGN that are triggered by not only stochastic accretion but also tidally induced accretion an…
A High Resolution Search for Dual AGN Candidates in Mergers: A Pre-Selection Strategy using Keck AO
George Mason University（乔治梅森大学）；University of California, Riverside（加州大学河滨分校）；U.S. Naval Observatory（美国海军天文台）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；Ehime University（爱媛大学）；U.S. Naval Research Laboratory（美国海军研究实验室）；University of Florida（佛罗里达大学）；University of Maryland（马里兰大学）
Feedback processes from active galactic nuclei (AGN) are thought to play a crucial role in regulating star formation in massive galaxies. Previous studies using \textit{Herschel} have resulted in conflicting conclusions as to whether star formation is quenched, enhanced, or not affected by AGN feedback. We use new deep 850 $μ$m observations from the SCUBA-2 Cosmology Legacy survey (S2CLS) to investigate star formation in a sample of X-ray selected AGN, probing galaxies up to $L_{0.5-7~\rm keV} = 10^{46}$ erg s$^{-1}$. Here we present the results of our analysis on a sample of 1957 galaxies at …
We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of giant low surface brightness (GLSB) galaxies. GLSB galaxies are extreme late type spirals that are large, isolated and poorly evolved compared to regular spiral galaxies. Earlier studies have indicated that their nuclei have relatively low mass black holes. Using data from the Sloan Digital Sky Survey (SDSS), we selected a sample of 30 GLSB galaxies that showed broad H$α$ emission lines in their AGN spectra. In some galaxies such as UGC 6284, the broad component of H$α$ is more related to…
We combine two approaches to isolate the AGN luminosity at near-infrared wavelengths and relate the near-IR pure AGN luminosity to other tracers of the AGN. Using integral-field spectroscopic data of an archival sample of 51 local AGNs, we estimate the fraction of non-stellar light by comparing the nuclear equivalent width of the stellar 2.3 micron CO absorption feature with the intrinsic value for each galaxy. We compare this fraction to that derived from a spectral decomposition of the integrated light in the central arc second and find them to be consistent with each other. Using our estima…
As part of our KMOS AGN Survey at High-redshift (KASHz), we present spatially-resolved VLT/KMOS and VLT/SINFONI spectroscopic data and ALMA 870$μ$m continuum imaging of eight $z$=1.4--2.6 moderate AGN ($L_{\rm 2-10 \rm kev}$ = $10^{42} - 10^{45}$ ergs s$^{-1}$). We map [OIII], H$α$ and rest-frame FIR emission to search for any spatial anti-correlation between ionised outflows (traced by the [OIII] line) and star formation (SF; traced by H$α$ and FIR), that has previously been claimed for some high-z AGN and used as evidence for negative and/or positive AGN feedback. Firstly, we conclude that H…
Despite their reputation as being "red and dead", the unique environment inhabited by Brightest Cluster Galaxies (BCGs) can often lead to a self-regulated feedback cycle between radiatively cooling intracluster gas and star formation and AGN activity in the BCG. However the prevalence of "active" BCGs, and details of the feedback involved, are still uncertain. We have performed an optical, UV and Mid-IR photometric analysis of the BCGs in 981 clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using Pan-STARRS PS1 3pi, GALEX and WISE survey data we look for BCGs with photometri…
We present a multi-wavelength analysis of two highly magnified strong gravitationally lensed galaxies, CLASS B0712+472 and CLASS B1608+656, at redshifts $1.34$ and $1.394$, respectively, using new VLBI and archival HST observations. We reconstruct the positions of the radio and optical emissions with their uncertainties using Monte Carlo sampling. We find that in CLASS B0712+472 the optical and radio emissions are co-spatial within $2\pm5$ mas ($17\pm 42$ pc at redshift of 1.34). But, in CLASS B1608+656, we reconstruct an optical-radio offset of $25\pm16$ mas ($214\pm137$ pc at redshift of 1.3…
Using $I$-band images of 35 nearby ($z<0.1$) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly measure the $I$-band brightness and the effective radius of bulges in our sample. Along with black hole (BH) mass estimates from single-epoch spectroscopic data, we present the relation between BH mass and $I$-band bulge luminosity ($M_{\rm BH}-M_{I,\r…
We present the results of a stacking analysis performed on Spitzer/Infrared Spectrograph high-resolution mid-infrared spectra of luminous infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey (GOALS). By binning on mid-infrared active galactic nucleus (AGN) fraction and stacking spectra, we detect bright emission lines [Ne II] and [Ne III], which trace star formation, and fainter emission lines [Ne V] and [O IV], which trace AGN activity, throughout the sample. We find the [Ne II] luminosity is fairly constant across all AGN fraction bins, while the [O IV] and [Ne V] luminos…
We have performed a spectral decomposition to search for dual active galactic nuclei (DAGNs) in the Sloan Digital Sky Survey (SDSS) quasars with $z<0.25$. Potential DAGN candidates are searched by referencing velocity offsets and spectral shapes of double-peaked [O III] lines of known DAGNs. Out of 1271 SDSS quasars, we have identified 77 DAGN candidates. Optical and mid-infrared diagnostic diagrams are used to investigate the ionizing source in the DAGN candidates. The optical diagnostic analysis suggests 93\% of them are powered by AGNs, and mid-infrared diagnostic analysis suggests 97\% are…
We use a suite of hydrodynamical simulations of galaxy mergers to compare star formation rate (SFR) and black hole accretion rate (BHAR) for galaxies before the interaction ('stochastic' phase), during the `merger' proper, lasting ~0.2-0.3 Gyr, and in the `remnant' phase. We calculate the bi-variate distribution of SFR and BHAR and define the regions in the SFR-BHAR plane that the three phases occupy. No strong correlation between BHAR and galaxy-wide SFR is found. A possible exception are galaxies with the highest SFR and the highest BHAR. We also bin the data in the same way used in several …
The SHINING survey (Paper I; Herrera-Camus et al. 2018) offers a great opportunity to study the properties of the ionized and neutral media of galaxies from prototypical starbursts and active galactic nuclei (AGN) to heavily obscured objects. Based on Herschel/PACS observations of the main far-infrared (FIR) fine-structure lines, in this paper we analyze the physical mechanisms behind the observed line deficits in galaxies, the apparent offset of luminous infrared galaxies (LIRGs) from the mass-metallicity relation, and the scaling relations between [CII] 158 $μ$m line emission and star format…
Does the Fundamental Metallicity Relation Evolve with Redshift? I: The Correlation Between Offsets from the Mass-Metallicity Relation and Star Formation Rate
We present the Advanced Camera for Surveys Active Galactic Nuclei (ACS-AGN) Catalog, a catalog of 2585 active galactic nucleus (AGN) host galaxies that are at redshifts 0.2<z<2.5 and that were imaged with the Hubble Space Telescope's Advanced Camera for Surveys (ACS). Using the ACS General Catalog (ACS-GC) as our initial sample, we select an AGN subsample using Spitzer and Chandra data along with their respective established AGN selection criteria. We then gather further multi-wavelength photometric data in order to construct spectral energy distributions (SEDs). Using these SEDs we are able t…
