bluuebunny/crossref_metadata_2025_split huggingface dataset:
Active galactic nuclei signatures in Red Geyser galaxies from Gemini GMOS-IFU observations
Authors: Ilha Gabriele S , Riffel Rogemar A , Ricci Tiago V , Rembold Sandro B , Storchi-Bergmann Thaisa , Riffel Rogério , Roy Namrata , Bundy Kevin , Nemmen Rodrigo , Schimoia Jáderson S , da Costa Luiz N 
Published: August 2022

ABSTRACTRed Geysers are quiescent galaxies with galactic scale ionized outflows, likely due to low-luminosity active galactic nuclei (AGN). We used Gemini GMOS-IFU observations of the inner ∼1–3 kpc of nine Red Geysers selected from the MaNGA survey to study the gas ionization and kinematics. The emission-line ratios suggest the presence of Seyfert/LINER (Low Ionization Nuclear Emission Region) nuclei in all sources. Two galaxies show  Hα equivalent width ( Hα EW) larger than 3 Å (indicative of AGN ionization) within an aperture 2 ${_{.}^{\prime\prime}}$5 of diameter (1.3–3.7 kpc at the distance of galaxies) for MaNGA data, while with the higher resolution GMOS data, four galaxies present  Hα EW&gt;3 Å within an aperture equal to the angular resolution (0.3–0.9 kpc). For two objects with GMOS-IFU data, the  Hα EW is lower than 3 Å but larger than 1.5 Å, most probably due to a faint AGN. The spatially resolved electron density maps show values between 100 and 3000 cm −3 and are consistent with those determined in other studies. The large (MaNGA) and the nuclear scale (GMOS-IFU) gas velocity fields are misaligned, with a kinematic position angle difference between 12° and 60°. The [N ii] λ6583 emission-line profiles are asymmetrical, with blue wings on the redshifted side of the velocity field and red wings on the blueshifted side. Our results support previous indications that the gas in Red Geysers is ionized by an AGN, at least in their central region, with the presence of outflows, likely originating in a precessing accretion disc.
Core-collapse supernovae in dense environments – particle acceleration and non-thermal emission
Authors: Brose R , Sushch I , Mackey J 
Published: August 2022

ABSTRACT
Supernova remnants (SNRs) are known to accelerate cosmic rays from the detection of non-thermal emission in radio waves, X-rays, and gamma-rays. However, the ability to accelerate cosmic rays up to PeV energies has yet to be demonstrated. The presence of cut-offs in the gamma-ray spectra of several young SNRs led to the idea that PeV energies might only be achieved during the first years of a remnant’s evolution. We use our time-dependent acceleration-code RATPaC to study the acceleration of cosmic rays in supernovae expanding into dense environments around massive stars. We performed spherically symmetric one-dimensional (1D) simulations in which we simultaneously solve the transport equations for cosmic rays, magnetic turbulence, and the hydrodynamical flow of the thermal plasma in the test-particle limit. We investigated typical circumstellar-medium (CSM) parameters expected around red supergiant (RSG) and luminous blue variable (LBV) stars for freely expanding winds and accounted for the strong γγ absorption in the first days after explosion. The maximum achievable particle energy is limited to below $600\,$TeV even for the largest considered values of the magnetic field and mass-loss rates. The maximum energy is not expected to surpass $\approx 200\,$ and $\approx 70\,$TeV for LBVs and RSGs that experience moderate mass-loss prior to the explosion. We find gamma-ray peak-luminosities consistent with current upper limits and evaluate that current-generation instruments are able to detect the gamma-rays from Type-IIP explosions at distances up to $\approx 60\,$ kpc and Type-IIn explosions up to $\approx 1.0\,$ Mpc. We also find a good agreement between the thermal X-ray and radio synchrotron emission predicted by our models with a range of observations.
Did a close tidal encounter cause the Great Dimming of Betelgeuse?
Authors: Aronson Hailey , Baumgarte Thomas W , Shapiro Stuart L 
Published: August 2022

ABSTRACT
We assess whether gravity darkening, induced by a tidal interaction during a stellar fly-by, might be sufficient to explain the Great Dimming of Betelgeuse. Adopting several simple approximations, we calculate the tidal deformation and associated gravity darkening in a close tidal encounter, as well as the reduction in the radiation flux as seen by a distant observer. We show that, in principle, the duration and degree of the resulting stellar dimming can be used to estimate the minimum pericentre separation and mass of a fly-by object, which, even if it remains undetected otherwise, might be a black hole, neutron star, or white dwarf. Our estimates show that, while such fly-by events may occur in other astrophysical scenarios, where our analysis should be applicable, they likely are not large enough to explain the Great Dimming of Betelgeuse by themselves.
Analytic models of dust temperature in high-redshift galaxies
Authors: Hirashita Hiroyuki , Chiang I-Da 
Published: August 2022

ABSTRACT
We investigate physical reasons for high-dust temperatures (Tdust ≳ 40K) observed in some high-redshift ($z$ &gt; 5) galaxies using analytic models. We consider two models that can be treated analytically: the radiative transfer (RT) model, where a broad distribution of values for Tdust is considered, and the one-tempearture (one-T) model, which assumes uniform Tdust. These two extremes serve to bracket the most realistic scenario. We adopt the Kennicutt–Schmidt (KS) law to relate stellar radiation field to gas surface density, and vary the dust-to-gas ratio. As a consequence, our model is capable of predicting the relation between the surface density of star formation rate (ΣSFR) or dust mass (Σdust) and Tdust. We show that the high Tdust observed at $z$ ≳ 5 favour low dust-to-gas ratios (≲ 10−3). An enhanced star formation compared with the KS law gives an alternative explanation for the high Tdust. The dust temperatures are similar between the two (RT and one-T) models as long as we use ALMA Bands 6–8. We also examine the relation among ΣSFR, Σdust, and Tdust without assuming the KS law, and confirm the consistency with the actual observational data at $z$ &gt; 5. In the one-T model, we also examine a clumpy dust distribution, which predicts lower Tdust because of the leakage of stellar radiation. This enhances the requirement of low-dust abundance or high-star formation efficiency to explain the observed high Tdust.
Three-dimensional structure of the central molecular zone
Authors: Sofue Yoshiaki 
Published: August 2022

ABSTRACT
A detailed comparison of H i and CO line cube data of the Galactic Centre (GC) region from the archives is obtained. The central molecular zone (CMZ) is shown to be embedded in the H i disc (central H i zone, CHZ) of radius ∼320 pc and vertical scale height ∼70 pc. A radio continuum belt is shown to run parallel to molecular Arms I and II. The belt draws a double infinity (∞∞) on the sky, connecting Sgr E (l ∼ −1${_{.}^{\circ}}$2), C, B1, B2, and Sgr D (+1${_{.}^{\circ}}$2), and is interpreted as a warping star-forming ring. The molecular Arms are closely associated with the H i arms on the longitude-velocity diagram (LVD), showing coherent rigid-body ridges. Due to the close relationship between H i and CO, the H i line absorption can be used to determine the Arms’ position relative to Sgr A, B1, B2, and C. Combining the trigonometric data of proper motions of Sgr A* and maser sources of Sgr B2 as well as radial velocities, the 3D velocity vector of Sgr B2 is determined. From these analyses, the molecular Arm I with Sgr B2 is shown to be located in the near side of Sgr A*, and Arm II with Sgr C in the other side, both composing a pair of symmetrical Arms around the GC. We present a possible 3D view of Sgr A through E and Arms I and II along with a parameter list.
Characterizing the daytime sextantids meteor shower and unveiling the nature of the phaethon-geminid stream complex
Authors: Kipreos Y , Campbell-Brown Margaret , Brown P , Vida D 
Published: August 2022

ABSTRACTThe Daytime Sextantids meteor shower, part of the Phaethon-Geminid Stream Complex (PGC), is closely related to the Geminids, currently the strongest meteor shower visible at the Earth. The Daytime Sextantids (DSX) share a similar orbit to asteroid 2005 UD, but the nature of the association remains unclear. From optical data we find that DSX meteors ablate similarly to Geminids, suggesting that they are also high density and consistent with a common origin. From radar data we have isolated 19 007 DSX orbits through application of a novel convex hull approach to determine stream membership. We find at the peak the mean semimajor axis is near 1 au, eccentricity is 0.86 and that both decrease as a function of solar longitude. The inclination averages 25 deg at the peak but increases over time. Noticeable DSX activity extends from solar longitude 173–196° with a flux plateau between 186 and 189°. The peak flux is 2 ± 0.05 × 10−3 km−2 hr−1, equivalent to a ZHR of 20. We estimate a true differential mass index for the shower of s = 1.64 ± 0.06 at the time of peak and an average of 1.70 ± 0.07 for days surrounding the peak. The mass of the DSX stream is estimated to be 1016 g, the same order as 2005 UD, suggesting the stream is too massive to have been created by recent meteoroid production from 2005 UD. We propose that the DSX and 2005 UD were created in the same break-up event that created 3200 Phaethon.
Nature of helicity injection in non-erupting solar active regions
Authors: Vemareddy P 
Published: August 2022

ABSTRACT
Using time-sequence vector magnetic field and coronal observations from Solar Dynamics Observatory, we report the observations of the magnetic field evolution and coronal activity in four emerging active regions (ARs). The ARs emerge with leading polarity being the same as for the majority of ARs in a hemisphere of solar cycle 24. After emergence, the magnetic polarities separate each other without building a sheared polarity inversion line. In all four ARs, the magnetic fields are driven by foot point motions such that the sign of the helicity injection (dH/dt) in the first half of the evolution is changed to the opposite sign in the later part of the observation time. This successive injection of opposite helicity is also consistent with the sign of mean force–free twist parameter (αav). Further, the EUV light curves off the ARs in 94 Å and GOES X-ray flux reveal flaring activity below C-class magnitude. Importantly, the white-light coronagraph images in conjunction with the AR images in Atmospheric Imaging Assembly (AIA) 94 Å delineate the absence of associated Coronal Mass ejections (CMEs) with the studied ARs. These observations imply that the ARs with successive injection of opposite sign magnetic helicity are not favourable to twisted flux rope formation with excess coronal helicity, and therefore are unable to launch CMEs, according to recent reports. This study provides the characteristics of helicity flux evolution in the ARs referring to the conservative property of magnetic helicity and more such studies would help to quantify the eruptive capability of a given AR.
The complex stellar system M 22: confirming abundance variations with high precision differential measurements
Authors: McKenzie M , Yong D , Marino A F , Monty S , Wang E , Karakas A I , Milone A P , Legnardi M V , Roederer I U , Martell S , Horta D 
Published: August 2022

ABSTRACT
M 22 (NGC 6656) is a chemically complex globular cluster-like system reported to harbour heavy element abundance variations. However, the extent of these variations and the origin of this cluster is still debated. In this work, we investigate the chemical in-homogeneity of M 22 using differential line-by-line analysis of high-quality (R = 110 000, S/N = 300 per pixel at 514 nm) VLT/UVES spectra of six carefully chosen red giant branch stars. By achieving abundance uncertainties as low as ∼0.01 dex (∼2 per cent), this high precision data validates the results of previous studies and reveals variations in Fe, Na, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Y, Zr, La, Ce, Nd, Sm, and Eu. Additionally, we can confirm that the cluster hosts two stellar populations with a spread of at least 0.24 dex in [Fe/H] and an average s-process abundance spread of 0.65 dex. In addition to global variations across the cluster, we also find non-negligible variations within each of the two populations, with the more metal-poor population hosting larger spreads in elements heavier than Fe than the metal-rich. We address previous works that do not identify anomalous abundances and relate our findings to our current dynamical understanding of the cluster. Given our results, we suggest that M 22 is either a nuclear star cluster, the product of two merged clusters, or an original building block of the Milky Way.
Probing dark matter with strong gravitational lensing through an effective density slope
Authors: Şengül Atinç Çagan , Dvorkin Cora 
Published: August 2022

ABSTRACT
Many dark matter (DM) models that are consistent with current cosmological data show differences in the predicted (sub)halo mass function, especially at sub-galactic scales, where observations are challenging due to the inefficiency of star formation. Strong gravitational lensing has been shown to be a useful tool for detecting dark low-mass (sub)haloes through perturbations in lensing arcs, therefore allowing the testing of different DM scenarios. However, measuring the total mass of a perturber from strong lensing data is challenging. Overestimating or underestimating perturber masses can lead to incorrect inferences about the nature of DM. In this paper, we argue that inferring an effective slope of the DM density profile, which is the power-law slope of perturbers at intermediate radii, where we expect the perturber to have the largest observable effect, is a promising way to circumvent these challenges. Using N-body simulations, we show that (sub)halo populations under different DM scenarios differ in their effective density slope distributions. Using realistic mocks of Hubble Space Telescope observations of strong lensing images, we show that the effective density slope of perturbers can be robustly measured with high enough accuracy to discern between different models. We also present our measurement of the effective density slope $\gamma =1.96\substack{+0.12 \\ -0.12}$ for the perturber in JVAS B1938+666, which is a 2σ outlier of the cold DM scenario. More measurements of this kind are needed to draw robust conclusions about the nature of DM.
Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields
Authors: Burke Colin J , Liu Xin , Shen Yue , Phadke Kedar A , Yang Qian , Hartley Will G , Harrison Ian , Palmese Antonella , Guo Hengxiao , Zhang Kaiwen , Kron Richard , Turner David J , Giles Paul A , Lidman Christopher , Chen Yu-Ching , Gruendl Robert A , Choi Ami , Amon Alexandra , Sheldon Erin , Aguena M , Allam S , Andrade-Oliveira F , Bacon D , Bertin E , Brooks D , Rosell A Carnero , Kind M Carrasco , Carretero J , Conselice C , Costanzi M , da Costa L N , Pereira M E S , Davis T M , De Vicente J , Desai S , Diehl H T , Everett S , Ferrero I , Flaugher B , García-Bellido J , Gaztanaga E , Gruen D , Gschwend J , Gutierrez G , Hinton S R , Hollowood D L , Honscheid K , Hoyle B , James D J , Kuehn K , Maia M A G , Marshall J L , Menanteau F , Miquel R , Morgan R , Paz-Chinchón F , Pieres A , Malagón A A Plazas , Reil K , Romer A K , Sanchez E , Schubnell M , Serrano S , Sevilla-Noarbe I , Smith M , Suchyta E , Tarle G , Thomas D , To C , Varga T N , Wilkinson R D ,   (DES Collaboration)
Published: August 2022

ABSTRACT
We present a sample of 706, z &lt; 1.5 active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg2. We construct light curves using difference imaging aperture photometry for resolved sources and non-difference imaging PSF photometry for unresolved sources, respectively, and characterize the variability significance. Our DES light curves have a mean cadence of 7 d, a 6-yr baseline, and a single-epoch imaging depth of up to g ∼ 24.5. Using spectral energy distribution (SED) fitting, we find 26 out of total 706 variable galaxies are consistent with dwarf galaxies with a reliable stellar mass estimate ($M_{\ast }\lt 10^{9.5}\, {\rm M}_\odot$; median photometric redshift of 0.9). We were able to constrain rapid characteristic variability time-scales (∼ weeks) using the DES light curves in 15 dwarf AGN candidates (a subset of our variable AGN candidates) at a median photometric redshift of 0.4. This rapid variability is consistent with their low black hole (BH) masses. We confirm the low-mass AGN nature of one source with a high S/N optical spectrum. We publish our catalogue, optical light curves, and supplementary data, such as X-ray properties and optical spectra, when available. We measure a variable AGN fraction versus stellar mass and compare to results from a forward model. This work demonstrates the feasibility of optical variability to identify AGNs with lower BH masses in deep fields, which may be more ‘pristine’ analogues of supermassive BH seeds.
Observational window effects on multi-object reverberation mapping
Authors: Malik Umang , Sharp Rob , Martini Paul , Davis Tamara M , Tucker Brad E , Yu Zhefu , Penton Andrew , Lewis Geraint F , Calcino Josh 
Published: August 2022

ABSTRACT
Contemporary reverberation mapping campaigns are employing wide-area photometric data and high-multiplex spectroscopy to efficiently monitor hundreds of active galactic nuclei (AGNs). However, the interaction of the window function(s) imposed by the observation cadence with the reverberation lag and AGN variability time-scales (intrinsic to each source over a range of luminosities) impact our ability to recover these fundamental physical properties. Time dilation effects due to the sample source redshift distribution introduce added complexity. We present comprehensive analysis of the implications of observational cadence, seasonal gaps, and campaign baseline duration (i.e. the survey window function) for reverberation lag recovery. We find that the presence of a significant seasonal gap dominates the efficacy of any given campaign strategy for lag recovery across the parameter space, particularly for those sources with observed-frame lags above 100 d. Using the Australian Dark Energy Survey as a baseline, we consider the implications of this analysis for the 4MOST/Time-Domain Extragalactic Survey campaign providing concurrent follow-up of the Legacy Survey of Space and Time deep-drilling fields, as well as upcoming programmes. We conclude that the success of such surveys will be critically limited by the seasonal visibility of some potential field choices, but show significant improvement from extending the baseline. Optimizing the sample selection to fit the window function will improve survey efficacy.
Pulsar radio emission mechanism – II. On the origin of relativistic Langmuir solitons in pulsar plasma
Authors: Rahaman Sk Minhajur , Mitra Dipanjan , Melikidze George I , Lakoba Taras 
Published: August 2022

ABSTRACT
Observations suggest that coherent radio emission from pulsars is excited in a dense pulsar plasma by curvature radiation from charge bunches. Numerous studies propose that these charge bunches are relativistic charge solitons that are solutions of the non-linear Schrödinger equation (NLSE) with a group velocity dispersion (G), cubic non-linearity (q), and non-linear Landau damping (s). The formation of stable solitons crucially depends on the parameters G, q, and s as well as the particle distribution function (DF). In this work, we use realistic pulsar plasma parameters obtained from observational constraints to explore the parameter space of NLSE for two representative DFs of particles’ momenta: Lorentzian (long-tailed) and Gaussian (short-tailed). The choice of DFs critically affects the value of |s/q|, which, in turn, determines whether solitons can form. Numerical simulations show that well-formed solitons are obtained only for small values of |s/q| ≲ 0.1, while for moderate and higher values of |s/q| ≳ 0.5 soliton formation is suppressed. Small values for |s/q| ∼ 0.1 are readily obtained for long-tailed DF for a wide range of plasma temperatures. On the other hand, short-tailed DF provides these values only for some narrow range of plasma parameters. Thus, the presence of a prominent high-energy tail in the particle DF favours soliton formation for a wide range of plasma parameters. Besides pair plasma, we also include an iron ion component and find that they make a negligible contribution in either modifying the NLSE coefficients or contributing to charge separation.
Detailed study of extended γ-ray morphology in the vicinity of the Coma cluster with Fermi Large Area Telescope
Authors: Baghmanyan Vardan , Zargaryan Davit , Aharonian Felix , Yang Ruizhi , Casanova Sabrina , Mackey Jonathan 
Published: August 2022

ABSTRACT
Galaxy clusters can be sources of high-energy (HE) γ-ray radiation due to the efficient acceleration of particles exceeding EeV energies. At present, though, the only candidate for emitting HE γ-rays is the Coma cluster, towards which an excess of γ-ray emission has been detected by the Fermi Large Area Telescope (Fermi-LAT). Using ∼12.3 yr of Fermi-LAT data, we explored the region of the Coma cluster between energies 100 MeV and 1 TeV by detailed spectral and morphological analysis. In the region of the Coma cluster, we detected diffuse γ-ray emission of energies between 100 MeV and 1 TeV with a 5.4σ extension significance and a 68 per cent containment radius of $0.82^{+0.10}_{-0.05}$ degrees derived with a two-dimensional homogeneous disc model. The corresponding γ-ray spectrum extends up to ∼50 GeV, with a power-law index of Γ = 2.23 ± 0.11 and flux of $\mathrm{(3.84\pm 0.67)\times 10^{-12}\, erg\, cm^{-2}\, s^{-1}}$. Using energy arguments we show that point-like sources such as radiogalaxies and star-forming galaxies are unlikely to explain the emission, and more likely, the emission is produced in the Coma cluster. Besides, we also identified three point-like sources in the region. However, because of limited statistics, we could neither exclude nor confirm the contribution of three point-like sources to the total emissions.
The effect of ionizing background fluctuations on the spatial correlations of high redshift Lyα-emitting galaxies
Authors: Meiksin Avery , Suarez Teresita 
Published: August 2022

ABSTRACT
We investigate the possible influence of fluctuations in the metagalactic photoionizing ultraviolet background (UVBG) on the clustering of Lyα-emitting galaxies through the modulation of the ionization level of the gas surrounding the systems. At redshift z &gt; 5, even when assuming the reionization of the intergalactic medium has completed, the fluctuations are sufficiently large that they may non-negligibly enhance, and possibly even dominate, the angular correlation function on scales up to a few hundred arcsecs. Whilst a comparison with observations at z ≃ 5.7 is statistically consistent with no influence of UVBG fluctuations, allowing for the fluctuations opens up the range of acceptable models to include those with relatively low bias factors for the Lyα-emitting galaxies. In this case, the evolution in the bias factor of Lyα-emitters over the approximate redshift range 3 &lt; z &lt; 7 corresponds to a nearly constant halo mass for Lyα-emitting galaxies of ∼1010.5 M⊙.