Abstract
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 and correlated accretion. With the level of stochastically triggered AGN fixed by the control sample, we model the strength of tidally induced accretion and correlated accretion as a function of projected separation (
r
p
) and compare the model expectations with the observed volume densities of dual AGN and offset AGN (single AGN in a pair). At
r
p
∼ 10 kpc, we find that tidal interactions induce ∼30% more AGN than stochastic fueling and cause ∼12% of the offset AGN to become dual AGN because of correlations. The strength of both these effects decreases with increasing
r
p
. We also find that the O
iii
luminosities of the AGN in galaxy pairs are consistent with those found in isolated galaxies, likely because stochastically fed AGN dominate even among close pairs. Our results illustrate that while we can detect tidally induced effects statistically, it is challenging to separate tidally induced AGN and stochastically triggered AGN in interacting galaxies.
We have identified 105 galaxy pairs at z ∼ 0.04 with the MaNGA integral-field spectroscopic data. The pairs have projected separations between 1 and 30 kpc, and are selected to have radial velocity ...offsets less than 600 km s−1 and stellar mass ratio between 0.1 and 1. The pair fraction increases with both the physical size of the integral-field unit and the stellar mass, consistent with theoretical expectations. We provide the best-fit analytical function of the pair fraction and find that ∼3% of M* galaxies are in close pairs. For both isolated galaxies and paired galaxies, active galactic nuclei (AGNs) are selected using emission-line ratios and H equivalent widths measured inside apertures at a fixed physical size. We find AGNs in ∼24% of the paired galaxies and binary AGNs in ∼13% of the pairs. To account for the selection biases in both the pair sample and the MaNGA sample, we compare the AGN comoving volume densities with those expected from the mass- and redshift-dependent AGN fractions. We find a strong (∼5×) excess of binary AGNs over random pairing and a mild (∼20%) deficit of single AGNs. The binary AGN excess increases from ∼2× to ∼6× as the projected separation decreases from 10-30 to 1-10 kpc. Our results indicate that the pairing of galaxies preserves the AGN duty cycle in individual galaxies but increases the population of binary AGNs through correlated activities. We suggest tidally induced galactic-scale shocks and AGN cross-ionization as two plausible channels to produce low-luminosity narrow-line-selected binary AGNs.
Abstract
We test the merger-induced dual active galactic nuclei (dAGNs) paradigm using a sample of 35 radio galaxy pairs from the Sloan Digital Sky Survey Stripe 82 field. Using Keck optical ...spectroscopy, we confirm 21 pairs have consistent redshifts, constituting kinematic pairs; the remaining 14 pairs are line-of-sight projections. We classify the optical spectral signatures via emission line ratios, equivalent widths, and excess of radio power above star formation predicted outputs. We find six galaxies are classified as LINERs and seven are AGN/starburst composites. Most of the LINERs are retired galaxies, while the composites likely have AGN contribution. All of the kinematic pairs exhibit radio power more than 10× above the level expected from just star formation, suggestive of a radio AGN contribution. We also analyze high-resolution (0.″3) imaging at 6 GHz from the NSF’s Karl G. Jansky Very Large Array for 17 of the kinematic pairs. We find six pairs (two new, four previously known) host two separate radio cores, confirming their status as dAGNs. The remaining 11 pairs contain single AGNs, with most exhibiting prominent jets/lobes overlapping their companion. Our final census indicates a dAGN duty cycle slightly higher than predictions of purely stochastic fueling, although a larger sample (potentially culled from VLASS) is needed to fully address the dAGN fraction. We conclude that while dAGNs in the Stripe 82 field are rare, the merger process plays some role in their triggering and it facilitates low to moderate levels of accretion.
Abstract
We compare the radial profiles of the specific star formation rate (sSFR) in a sample of 169 star-forming galaxies in close pairs with those of mass-matched control galaxies in the SDSS-IV ...MaNGA survey. We find that the sSFR is centrally enhanced (within one effective radius) in interacting galaxies by ∼0.3 dex and that there is a weak sSFR suppression in the outskirts of the galaxies of ∼0.1 dex. We stack the difference profiles for galaxies in five stellar-mass bins in the range log(
M
/
M
⊙
) = 9.0–11.5 and find that the sSFR enhancement has no dependence on the stellar mass. The same result is obtained when comparison galaxies are matched to each paired galaxy in both stellar mass and redshift. In addition, we find that the sSFR enhancement is elevated in pairs with nearly equal masses and closer projected separations, in agreement with previous work based on single-fiber spectroscopy. We also find that the sSFR offsets in the outskirts of the paired galaxies are dependent on whether the galaxy is the more-massive or less-massive companion in the pair. The more-massive companion experiences zero to a positive sSFR enhancement, while the less-massive companion experiences sSFR suppression in their outskirts. Our results illustrate the complex tidal effects on star formation in closely paired galaxies.
The analytical utility of a new and simple to use ionization method, matrix-assisted ionization (MAI), coupled with ion mobility spectrometry (IMS) and mass spectrometry (MS) is used to characterize ...a 2-armed europium(III)-containing poly(ethylene glycol) (Eu-PEG) complex directly from a crude sample. MAI was used with the matrix 1,2-dicyanobenzene, which affords low chemical background relative to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI). MAI provides high ion abundance of desired products in comparison to ESI and MALDI. Inductively coupled plasma-MS measurements were used to estimate a maximum of 10% of the crude sample by mass was the 2-arm Eu-PEG complex, supporting evidence of selective ionization of Eu-PEG complexes using the new MAI matrix, 1,2-dicyanobenzene. Multiply charged ions formed in MAI enhance the IMS gas-phase separation, especially relative to the singly charged ions observed with MALDI. Individual components are cleanly separated and readily identified, allowing characterization of the 2-arm Eu-PEG conjugate from a mixture of the 1-arm Eu-PEG complex and unreacted starting materials. Size-exclusion chromatography, liquid chromatography at critical conditions, MALDI-MS, ESI-MS, and ESI-IMS-MS had difficulties with this analysis, or failed.
Graphical Abstract
ᅟ
In October 2020, the National Cancer Institute (NCI) Serological Sciences Network (SeroNet) was established to study the immune response to COVID-19, and "to develop, validate, improve, and implement ...serological testing and associated technologies" (https://www.cancer.gov/research/key-initiatives/covid-19/coronavirus-research-initiatives/serological-sciences-network). SeroNet is comprised of 25 participating research institutions partnering with the Frederick National Laboratory for Cancer Research (FNLCR) and the SeroNet Coordinating Center. Since its inception, SeroNet has supported collaborative development and sharing of COVID-19 serological assay procedures and has set forth plans for assay harmonization. To facilitate collaboration and procedure sharing, a detailed survey was sent to collate comprehensive assay details and performance metrics on COVID-19 serological assays within SeroNet. In addition, FNLCR established a protocol to calibrate SeroNet serological assays to reference standards, such as the U.S. severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology standard reference material and first WHO international standard (IS) for anti-SARS-CoV-2 immunoglobulin (20/136), to facilitate harmonization of assay reporting units and cross-comparison of study data. SeroNet institutions reported development of a total of 27 enzyme-linked immunosorbent assay (ELISA) methods, 13 multiplex assays, and 9 neutralization assays and use of 12 different commercial serological methods. FNLCR developed a standardized protocol for SeroNet institutions to calibrate these diverse serological assays to reference standards. In conclusion, SeroNet institutions have established a diverse array of COVID-19 serological assays to study the immune response to SARS-CoV-2 and vaccines. Calibration of SeroNet serological assays to harmonize results reporting will facilitate future pooled data analyses and study cross-comparisons.
SeroNet institutions have developed or implemented 61 diverse COVID-19 serological assays and are collaboratively working to harmonize these assays using reference materials to establish standardized reporting units. This will facilitate clinical interpretation of serology results and cross-comparison of research data.
Abstract
We provide a catalog of visually classified objects in the MaNGA integral field spectroscopic survey. The MaNGA survey is designed to target a single galaxy with each of its integral field ...units; however, many of these fields will host ancillary objects. We identify these discrete objects by cleaning up SDSS photometric objects in MaNGA’s fields-of-view. We then use the spectra from MaNGA’s data cubes to spectrally classify the identified objects. The catalog contains the positions and classifications of 1385 stars, 11,439 galaxies, and 107 broad-line active galactic nucleus (BLAGN) from the 10,130 unique MaNGA fields. We also provide spectroscopically derived parameters for the galaxies including; stellar masses, gas and stellar kinematics, and emission-line fluxes and equivalent widths. This catalog effectively expands the size of the MaNGA catalog by ∼50%, increasing the utility of the MaNGA project.
Hydrodynamical simulations of galaxy mergers have suggested that merger-induced gas-inflows may be able to fuel the central supermassive black hole (SMBH), triggering an active galactic nucleus ...(AGN). Despite the results of these simulations, observational studies disagree on whether or not there is merger-induced AGN. We use the recently completed integral field spectroscopic (IFS) survey, MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), to study the volume densities and OIII luminosities of AGN in paired galaxies. We build a sample of 387 spectroscopically confirmed galaxy pairs of which 102 host an AGN and a sample of 24 dual AGN (dAGN). We find that the volume density of AGN in galaxy pairs is higher than what would be expected by the random pairing of stochastically triggered AGN. At close separations, the volume density of AGN in pairs is 2.5x what is expected from the random pairing of AGN. We further find that the volume density of dAGN under separations of 4 kpc is 40x what we would expect from the random pairing of stochastically triggered AGN. We find that neither correlated AGN activity nor merger-induced fueling can fully explain the excess AGN volume density. Instead, we find that a model that includes stochastic fueling, merger-induced fueling, and correlated AGN activity is required to fully explain the excess AGN in our sample of galaxy pairs. We also find that the AGN in our galaxy pairs feature enhanced levels of OIII luminosity in comparison to the AGN in isolated control galaxies to the order of 0.1-0.4 dex. The enhanced volume density and OIII luminosity demonstrates the impact that galaxy interactions have on the development of the supermassive black holes (SMBH) found in the centers of galaxies.
We use the MaNGA integral field spectroscopic (IFS) survey to study star formation in interacting galaxies. We identify a set of galaxy pairs both inside and outside of the MaNGA survey's field of ...view. We build radial profiles of specific star formation rate (sSFR) for the MaNGA targets with spectroscopic pairs and compare their profiles against a set of isolated control galaxies. We study how these profiles are affected by the stellar mass of the galaxy, the mass ratio between the galaxies, and the projected separations between the galaxies. We find that galaxy pairs tend to have centrally enhanced sSFR of about 0.25 $\pm$ 0.1 dex in their centers. This level of enhancement is found to be unaffected by the stellar mass of the galaxy, is strongest in galaxy pairs with 1:1 mass ratios, and is also strongest at projected separations of 5$-$10 kpc. Galaxy pairs with projected separations below 5 kpc are found to have no enhancements to sSFR in comparison to control galaxies, which indicates a delay between the passage of the first pericenter and the arrival of the gas inflows to the centers of the galaxies. The centrally enhanced star formation rate causes the paired galaxies to experience an increased mass growth rate of $\sim$1.5$-$6.5\% in their centers, which is roughly 1.6$\times$ faster than secular evolution.
We provide a catalog of visually classified objects in the MaNGA integral field spectroscopic survey. The MaNGA survey is designed to target a single galaxy with each of its integral field units; ...however, many of these fields will host ancillary objects. We identify these discrete objects by cleaning up SDSS photometric objects in MaNGA's fields-of-view. We then use the spectra from MaNGA's data cubes to spectrally classify the identified objects. The catalog contains the positions and classifications of 1385 stars, 11,439 galaxies, and 107 broad-line active galactic nucleus (BLAGN) from the 10,130 unique MaNGA fields. We also provide spectroscopically derived parameters for the galaxies including; stellar masses, gas and stellar kinematics, and emission-line fluxes and equivalent widths. This catalog effectively expands the size of the MaNGA catalog by ~50%, increasing the utility of the MaNGA project.
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