Search

We study vertical resonant trapping and resonant heating of orbits. These two processes both lead to the growth of a boxy/peanut-shaped bulge in a typical $N$-body model. For the first time, we study this by means of the action variables and resonant angles of the actual orbits that compose the model itself. We used the resonant angle instead of the frequency ratio, which allowed us to clearly distinguish between these two processes in numerical simulations. We show that trapping and heating occur simultaneously, at least at the stage of a mature bar, that is, some orbits quickly pass through vertical resonance while at the same time, a substantial number of orbits remains trapped into this stage for a long time. Half of all bar orbits spend more than 2.5 Gyr in vertical resonance over an interval of 4 Gyr. Half of the orbits trapped into the bar over the last 3 Gyr of simulation remain captured in vertical resonance for more than 2 Gyr. We conclude that in the later stages of the bar evolution, the process of vertical trapping dominates in the ongoing process that causes the boxy/peanut shape of a bar in a typical $N$-body model. This contradicts the results of several recent works., Comment: Accepted for publication in A&A

Simulations and observations suggest that galaxy interactions may enhance the star formation rate (SFR) in merging galaxies. One proposed mechanism is the torque exerted on the gas and stars in the larger galaxy by the smaller galaxy. We analyze the interaction torques and star formation activity on six galaxies from the FIRE-2 simulation suite with masses comparable to the Milky Way galaxy at redshift $z=0$. We trace the halos from $z = 3.6$ to $z=0$, calculating the torque exerted by the nearby galaxies on the gas in the central galaxy. We calculate the correlation between the torque and the SFR across the simulations for various mass ratios. For near-equal-stellar-mass-ratio interactions in the galaxy sample, occurring between $z=1.2-3.6$, there is a positive and statistically significant correlation between the torque from nearby galaxies on the gas of the central galaxies and the SFR. For all other samples, no statistically significant correlation is found between the torque and the SFR. Our analysis shows that some, but not all, major interactions cause starbursts in the simulated Milky Way-mass galaxies, and that most starbursts are not caused by galaxy interactions. The transition from `bursty' at high redshift ($z\gtrsim1$) to `steady' star-formation state at later times is independent of the interaction history of the galaxies, and most of the interactions do not leave significant imprints on the overall trend of the star formation history of the galaxies., Comment: Submitted to ApJ

The characterization of magnetic fields within molecular clouds is fundamental to understanding star formation processes. Accurately gauging the three-dimensional structure of these fields presents a challenge, as observational techniques such as dust polarization and the Zeeman effect each provide only partial information on the orientation and line-of-sight strength, respectively. By analyzing a suite of AREPO simulations, this paper investigates how observables can relate to underlying physical properties to derive a more comprehensive picture of the magnetic field's inclination angle and strength, specifically in regions where both dust polarization and Zeeman data are available. To demonstrate the method, we produce synthetic observations of the polarization angle dispersion and line-of-sight Alfv\'en Mach Number and explore the behavior of the inclination angle, $\gamma$, and strength of the magnetic field in regions where both Zeeman and dust polarization data are available. We find that dust polarization data can be used to determine the inclination angle if the cloud is known to be trans-Alfv\'enic or sub-Alfv\'enic. The strength of the magnetic field relative to turbulence can be estimated by comparing polarization observations to Zeeman observations. Comparing the dispersion of the polarization angle to the estimated line-of-sight Alfv\'en Mach Number provides clues about the strength of the magnetic field and, consequently, the orientation of the magnetic field., Comment: 16 pages, 12 figures, 1 table

We report the discovery of a rare isolated group of five dwarf galaxies located at z = 0.0086 ($D$ = 36 Mpc). All member galaxies are star-forming, blue, and gas-rich with $g-r$ indices ranging from 0.2 to 0.6 mag, and two of them show signs of ongoing mutual interaction. The most massive member of the group has a stellar mass that is half of the Small Magellanic Cloud stellar mass, and the median stellar mass of the group members is 7.87 $\times$ 10$^{7}$ M$_{\odot}$. The derived total dynamical mass of the group is $M_{\rm dyn}$ = 6.02$\times$10$^{10}$ M$_{\odot}$, whereas its total baryonic mass (stellar + HI) is 2.6$\times$10$^{9}$ M$_{\odot}$, which gives us the dynamical to baryonic mass ratio of 23. Interestingly, all galaxies found in the group are aligned along a straight line in the plane of the sky. The observed spatial extent of the member galaxies is 154 kpc, and their relative line-of-sight velocity span is within 75 km s$^{-1}$. Using the spatially resolved optical spectra provided by DESI EDR, we find that three group members share a common rotational direction. With these unique properties of the group and its member galaxies, we discuss the possible importance of such a system in the formation and evolution of dwarf galaxy groups and in testing the theory of large-scale structure formation., Comment: Accepted for publication in ApJL

The distribution of chemical elements in the Galactic disc can reveal fundamental clues on the physical processes that led to the current configuration of our Galaxy. We map chemical azimuthal variations in the disc using individual stellar chemical abundances and discuss their possible connection with the spiral arms and other perturbing mechanisms. Using Gaia Data Release 3, we examine [Ca/Fe] and [Mg/Fe] fluctuations in a ~4 kpc region around the Sun, focusing on bright giant stars. We implemented a kernel density estimator technique to enhance the chemical inhomogeneities. We observe radial gradients and azimuthal fluctuations in [alpha/Fe] for young (<150 Myr) and old (>2 Gyr) stars, with amplitudes varying according to the studied element. In young stars, those within spiral arms (e.g., Sagittarius-Carina and Local arms) are generally more metal and calcium-rich (~0-0.19 dex) but show lower [Ca/Fe] (~0.06 dex) and [Mg/Fe] (~0.05 dex) compared to inter-arm regions, suggesting enhanced iron production in spiral arms. These [alpha/Fe] depletions are analysed in light of theoretical scenarios and compared to a 2D chemical evolution model with multiple spiral patterns. For the old sample, [Ca/Fe] maps reveal deficiencies along a segment of the Local arm identified by young stars. We caution that, for this old sample, the quality of the obtained maps might be limited along a specific line-of-sight, due to the Gaia scanning law. This study transitions our understanding of disc chemical evolution from a 1D radial view to a more detailed 2D framework incorporating radial, azimuthal, and small-scale variations. Individual chemical abundances prove essential for tracing spiral arms in disc galaxies. We recommend models and simulations incorporate alpha-abundance trends to better address spiral arm lifetimes.

To date, a number of changing-look (CL) active galactic nuclei (AGNs) are known. We studied, in detail what happens to the X-ray spectrum during the CL events using the example of the nearby CL Seyfert NGC1566, which was observed by Swift, NuSTAR, XMM-Newton, and Suzaku. We applied the Comptonization model to describe an evolution of NGC~1566 X-ray spectra during outbursts and compared these results with a typical behavior for other AGNs to identify some differences and common properties that can ultimately help us to better understand the physics of the CL phenomenon. We found that changes in the X-ray properties of NGC1566 are characterized by a different combination of Sy1 (using 1H0707-495 as a representative) and Sy2 properties (using NGC7679 and Mrk3 as their representatives). At high X-ray luminosities NGC1566 exhibits the behavior typical for Sy1, and at low luminosities we see a transition of NGC1566 from the Sy1 behavior to the Sy2 pattern. We revealed the saturation of the spectral indices, \=a for these four AGNs during outbursts (\=a_1566~1.1, \=a _0707~2, \=a _7679~0.9 and \=a_mrk3~0.9) and determined the masses of the black holes (BHs) in the centers of these AGNs namely, M_0707~6.8x10^7 M_sol, M_7679~8.4x10^6 M_sol, M_mrk3~2.2x10^8 M_sol and M_1566~2x10^5 M_sol, applying the scaling method. Our spectral analysis shows that the changing-look of NGC1566 from Sy1.2 to Sy1.9 in 2019 was accompanied by the transition of NGC1566 to an accretion regime which is typical for the intermediate and highly soft spectral states of other BHs. We also find that when going from Sy2 to Sy1, the spectrum of NGC1566 shows an increase in the soft excess accompanied by a decrease in the Comptonized fraction (0.1

We present contemporaneous high-angular-resolution millimeter imaging and visible polarimetric imaging of the nearby asymptotic giant branch (AGB) star W Hya to better understand the dynamics and dust formation within a few stellar radii. The star W Hya was observed in two vibrationally excited H2O lines at 268 and 251 GHz with ALMA at a spatial resolution of 16 x 20 mas and at 748 and 820 nm at a resolution of 26 x 27 mas with the VLT/SPHERE-ZIMPOL. ALMA's high spatial resolution allowed us to image strong emission of the vibrationally excited H2O line at 268 GHz (v2 = 2, J_K_a,K_c = 6_5,2 - 7_4,3) over the stellar surface instead of absorption against the continuum, which is expected for thermal excitation. Strong, spotty emission was also detected along and just outside the stellar disk limb at an angular distance of ~40 mas (~1.9 stellar radii), extending to ~60 mas (~2.9 stellar radii). Another H2O line (v2 = 2, J_K_a,K_c = 9_2,8 - 8_3,5) at 251 GHz with a similar upper-level energy was tentatively identified, which shows absorption over the stellar surface. This suggests that the emission over the surface seen in the 268 GHzH2O line is suprathermal or even maser emission. The estimated gas temperature and H2O density are consistent with the radiatively pumped masers. The 268 GHz H2O line reveals global infall at up to ~15 km/s within 2--3 stellar radii, but outflows at up to ~8 km/s are also present. The polarized intensity maps obtained in the visible reveal clumpy dust clouds forming within ~40 mas (~1.9 stellar radii) with a particularly prominent cloud in the SW quadrant and a weaker cloud in the east. The 268 GHz H2O emission overlaps very well with the visible polarized intensity maps, which suggests that both the nonthermal and likely maser H2O emission and the dust originate from dense, cool pockets in the inhomogeneous atmosphere within ~2--3 stellar radii., Comment: 10 pages, 7 figures, published in Astronomy and Astrophysics

The [C II] fine-structure line at 157.74 $\mu$m is one of the brightest far-infrared emission lines and an important probe of galaxy properties like the star formation rate (SFR) and the molecular gas mass ($M_{\mathrm{mol}}$). Using high-resolution numerical simulations, we test the reliability of the [C II] line as a tracer of $M_{\mathrm{mol}}$ in high-redshift galaxies and investigate secondary dependences of the [C II]-$M_{\mathrm{mol}}$ relation on the SFR and metallicity. We investigate the time evolution of the [C II] luminosity function (LF) and the relative spatial extent of [C II] emission and star formation. We post-process galaxies from the MARIGOLD simulations at redshifts $3 \le z \leq 7$ to obtain their [C II] emission. These simulations were performed with the sub-grid chemistry model, HYACINTH, to track the non-equilibrium abundances of $\mathrm{H_2}$, $\mathrm{CO}$, $\rm C$ and $\mathrm{C^+}$ on the fly. Based on a statistical sample of galaxies at these redshifts, we investigate correlations between the [C II] line luminosity, L([C II]), and the SFR, the $M_{\mathrm{mol}}$, the total gas mass and the metal mass in gas phase ($M_{\mathrm{metal}}$). We find that accounting for secondary dependencies in the L([C II])-$M_{\mathrm{mol}}$ relation improves the $M_{\mathrm{mol}}$ prediction by a factor of 2.3. The [C II] emission in our simulated galaxies shows the tightest correlation with $M_{\mathrm{metal}}$. About 20% (10%) of our simulated galaxies at $z=5$ ($z=4$) have [C II] emission extending $\geq 2$ times farther than the star formation activity. The [C II] LF evolves rapidly and is always well approximated by a double power law that does not show an exponential cutoff at the bright end. We record a 600-fold increase in the number density of L([C II]) $\sim 10^9 \, \mathrm{L_{\odot}}$ emitters in 1.4 Gyr., Comment: 25 pages, 20 figures. Submitted to A&A. Comments are welcome

The mass of galaxy clusters is a critical quantity for probing cluster cosmology and testing theories of gravity, but its measurement could be biased given assumptions are inevitable. In this paper, we employ and compare two mass proxies for galaxy clusters: thermodynamics of the intracluster medium and kinematics of member galaxies. We select 22 galaxy clusters from the cluster catalog in the first SRG/eROSITA All-Sky Survey (eRASS1) that have sufficient optical and near-infrared observations. We generate multi-band images in the energy range of (0.3, 7) keV for each cluster, and derive their temperature profiles, gas mass profiles and hydrostatic mass profiles using a parametric approach that does not assume dark matter halo models. With spectroscopically confirmed member galaxies collected from multiple surveys, we numerically solve the spherical Jeans equation for their dynamical mass profiles. Our results quantify the correlation between dynamical mass and line-of-sight velocity dispersion with an rms scatter of 0.14 dex. We find the two mass proxies lead to roughly the same total mass, with no observed systematic bias. As such, the $\sigma_8$ tension is not specific to hydrostatic mass or weak lensing shears, but also appears with galaxy kinematics. We also compare our hydrostatic masses with the latest weak lensing masses inferred with scaling relations. The comparison shows the weak lensing mass is significantly higher than our hydrostatic mass by $\sim$110%. This might explain the significantly larger value of $\sigma_8$ from the latest measurement using eRASS1 clusters than almost all previous estimates in the literature. Finally, we test the radial acceleration relation (RAR) established in disk galaxies. We confirm the missing baryon problem in the inner region of galaxy clusters using three independent mass proxies for the first time., Comment: 14 pages, 9 figures, 2 tables, with 12-page appendix for additional figures and tables. Accepted for publication in A&A

We present the first set of high-resolution, hydrodynamical cosmological simulations of galaxy formation in a Fuzzy Dark Matter (FDM) framework. These simulations were performed with a new version of the GASOLINE2 code, known as FUZZY-GASOLINE, which can simulate quantum FDM effects alongside a comprehensive baryonic model that includes metal cooling, star formation, supernova feedback, and black hole physics, previously used in the NIHAO simulation suite. Using thirty zoom-in simulations of galaxies with halo masses in the range $10^9 \lesssim M_{\text{halo}}/M_{\odot} \lesssim 10^{11}$, we explore how the interplay between FDM quantum potential and baryonic processes influences dark matter distributions and observable galaxy properties. Our findings indicate that both baryons and low-mass FDM contribute to core formation within dark matter profiles, though through distinct mechanisms: FDM-induced cores emerge in all haloes, particularly within low-mass systems at high redshift, while baryon-driven cores form within a specific mass range and at low redshift. Despite these significant differences in dark matter structure, key stellar observables such as star formation histories and velocity dispersion profiles remain remarkably similar to predictions from the Cold Dark Matter (CDM) model, making it challenging to distinguish between CDM and FDM solely through stellar observations., Comment: 13 pages, 8 figures, 6 tables. Paper submitted to MNRAS

We introduce the Data Analysis Pipeline (DAP) for the Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) project, referred to as the LVM-DAP. We outline our methods for recovering both stellar and emission line components from the optical integral field spectroscopy, highlighting the developments and changes implemented to address specific challenges of the data set. The observations from the LVM project are unique because they cover a wide range of physical resolutions, from approximately 0.05 pc to 100 pc, depending on the distance to the targets. This, along with the varying number of stars sampled in each aperture (ranging from zero, just one of a few, to thousands), presents challenges in using previous spectral synthesis methods and interpreting the spectral fits. We provide a detailed explanation of how we model the stellar content and separate it from the ionized gas emission lines. To assess the accuracy of our results, we compare them with both idealized and more realistic simulations, highlighting the limitations of our methods. We find that the DAP robustly correct for stellar continuum features and recover emission line parameters (e.g. flux, equivalent width, systemtic velocity and velocity dispersion) with a precision and accuracy that fulfill the requirements of the primary goal of the analysis. In addition, the recovered stellar parameters are reliable for single stars, the recovery of integrated populations is less precise. We conclude with a description of the data products we provide, instructions for downloading and using our software, and a showcase illustrating the quality of the data and the analysis on a deep exposure taken on the Huygens region at the center of the Orion Nebula., Comment: 35 pages, 17 figures, 8 tables, accepted for publication in AJ

Context: Extensive, multi-wavelength monitoring campaigns of nearby and higher redshift active galactic nuclei (AGN) have shown that the UV/optical variations are well correlated with time delays which increase with increasing wavelength. Such behaviour is expected in the context of the X-ray thermal reverberation of the accretion disc in AGN. Aims: Our main objective is to use time-lag measurements of luminous AGN and fit them with sophisticated X-ray reverberation time-lags models. In this way we can investigate whether X-ray reverberation can indeed explain the observed continuum time lags, and whether time-lag measurements can be used to measure physical parameters such as the X-ray corona height and the spin of the black hole (BH) in these systems. Methods: We use archival time-lag measurements for quasars from different surveys, and we compute their rest frame, mean time-lags spectrum. We fit the data with analytical X-ray reverberation models, using $\chi^2$ statistics, and fitting for both maximal and non spinning BHs, for various colour correction values and X-ray corona heights. Results: We found that X-ray reverberation can explain very well the observed time lags, assuming the measured BH mass, accretion rate and X-ray luminosity of the quasars in the sample. The model agrees well with the data both for non-rotating and maximally rotating BHs, as long as the corona height is larger than $\sim 40$ gravitational radii. This is in agreement with previous results which showed that X-ray reverberation can also explain the disc radius in micro-lensed quasars, for the same corona heights. The corona height we measure depends on the model assumption of a perfectly flat disc. More realistic disc models may result in lower heights for the X-ray corona., Comment: 10 pages, 7 figures

The VLT Survey Telescope Survey of Mass Assembly and Structural Hierarchy (VST-SMASH) aims to detect tidal features and remnants around very nearby galaxies, a unique and essential diagnostic of the hierarchical nature of galaxy formation. Leveraging optimal sky conditions at ESO's Paranal Observatory, combined with the VST's multi-band optical filters, VST-SMASH aims to be the definitive survey of stellar streams and tidal remnants in the Local Volume, targeting a low surface-brightness limit of $\mu \sim$ 30 mag arcsec$^{-2}$ in the g and r bands, and $\mu \sim$ 28 mag arcsec$^{-2}$ in the i band, in a volume-limited sample of local galaxies within 11 Mpc and the Euclid footprint., Comment: 4 pages, 2 figures, 1 table, published in the ESO Messenger 193

The Event Horizon Telescope Collaboration (EHTC) observed the Galactic centre source Sgr A* and used emission models primarily based on single ion temperature (1T) general relativistic magnetohydrodynamic (GRMHD) simulations. This predicted emission is strongly dependent on a modelled prescription of the ion-to-electron temperature ratio. The two most promising models are magnetically arrested disk (MAD) states. However, these and nearly all MAD models exhibit greater light-curve variability at 230 GHz compared to historical observations. Moreover, no model successfully passes all the variability and multiwavelength constraints. This limitation possibly stems from the fact that the actual temperature ratio depends on microphysical dissipation, radiative processes and other effects not captured in ideal fluid simulations. Therefore, we investigate the effects of two-temperature (2T) thermodynamics in MAD GRMHD simulations of Sgr A*, where the temperatures of both species are evolved more self-consistently. We include Coulomb coupling, radiative cooling of electrons, and model heating via magnetic reconnection. We find that the light-curve variability more closely matches historical observations when we include the 2T treatment and variable adiabatic indices, compared to 1T simulations. Contrary to the common assumption of neglecting radiative cooling for the low accretion rates of Sgr A*, we also find that radiative cooling still affects the accretion flow, reducing the electron temperature in the inner disk by about 10%, which in turn lowers both the average flux and variability at 230 GHz by roughly 10%.

The role of internal and environmental factors in the star formation activity of galaxies is still a matter of debate, particularly at higher redshifts. Leveraging the most recent release of the COSMOS catalog, COSMOS2020, and density measurements from our previous study we disentangle the impact of environment and stellar mass on the star formation rate (SFR), and specific SFR (sSFR) of a sample of $\sim 210,000$ galaxies within redshift range $0.4< z < 4$ and present our findings in three cosmic epochs: 1) out to $z\sim 1$, the average SFR and sSFR decline at extremely dense environments and high mass end of the distribution which is mostly due to the presence of the massive quiescent population; 2) at $1

We present and discuss two catalogues of UV-selected (NUV $< 22.8$ mag) galaxies that lie within a 200 deg$^2$ area of sky covered by the ASKAP FLASH survey and have an impact parameter of less than 20 arcsec to a FLASH radio continuum source. These catalogues are designed to enable a future search for 21 cm HI absorption in and around star-forming galaxies at redshift $0.480 percent) star-forming and resemble the overall WiggleZ population. The ($g - i$) colour evolution with redshift is consistent with a history of active star-formation, but the radio-associated objects are typically redder and have colours similar to high-excitation radio galaxies. The redshift distribution of the two catalogues matches the overall distribution for WiggleZ galaxies, despite their otherwise rare radio properties. These catalogues can be expanded in future as new radio data become available, and a forthcoming paper will present the HI absorption results., Comment: 22 pages, 18 figures, accepted for publication in MNRAS

Orbits of stellar binaries are in general eccentric. This encodes information about the formation process. Here, we use thousands of main-sequence binaries from the GAIA DR3 catalog to reveal that, binaries inwards of a few AU exhibit a simple Rayleigh distribution with a mode $\sigma_e \simeq 0.30$. We find the same distribution for binaries from M to A spectral types, and from tens of days to $10^3$days (possibly extending to tens of AU). This observed distribution is most likely primordial. Its Rayleigh form suggests an origin in weak scattering, while its invariant mode demands a universal process. We experiment with exciting binary eccentricities by ejecting brown dwarfs, and find that the eccentricities reach an equi-partition value of $\sigma_e \simeq \sqrt{M_{\rm bd}/M_*}$. So to explain the observed mode, these brown dwarfs will have to be of order one tenth the stellar masses, and be at least as abundant in the Galaxy as the close binaries. The veracity of such a proposal remains to be tested., Comment: 6 pages + 7 appendixes; submitted to ApJ Letters

The Gravitation Wave (GW) signals from a large number of double white dwarfs (DWDs) in the Galaxy are expected to be detected by space GW detectors, e.g., the Laser Interferometer Space Antenna (LISA), Taiji, and Tianqin in the millihertz band. In this paper, we present an alternative method by directly using the time-domain GW signal detected by space GW detectors to constrain the anisotropic structure of the Galaxy. The information of anisotropic distribution of DWDs is naturally encoded in the time-domain GW signal because of the variation of the detectors' directions and consequently the pattern functions due to their annual motion around the sun. The direct use of the time-domain GW signal enables simple calculations, such as utilizing an analytical method to assess the noise arising from the superposition of random phases of DWDs and using appropriate weights to improve the constraints. We investigate the possible constraints on the scale of the Galactic thin disk and bulge that may be obtained from LISA and Taiji by using this method with mock signals obtained from population synthesis models. We further show the different constraining capabilities of the low-frequency signal (foreground) and the high-frequency signal (resolvable-sources) via the Markov Chain Monte Carlo method, and find that the scale height and length of the Galactic thin disk and the scale radius of bulge can be constrained to a fractional accuracy of ~ 30%, 30%, 40% (or 20%, 10%, 40%) by using the low-frequency (or high-frequency) signal detected by LISA or Taiji., Comment: 20 pages, 8 figures, accepted for publication in ApJ

We present the first HI mass function (HIMF) measurement for the recent FAST All Sky HI (FASHI) survey and the most complete measurements of HIMF in the local universe so far by combining the HI catalogues from HI Parkes All Sky Survey (HIPASS), Arecibo Legacy Fast ALFA (ALFALFA) and FASHI surveys at redshift 0 < z < 0.05, covering 76% of the entire sky. We adopt the same methods to estimate distances, calculate sample completeness, and determine the HIMF for all three surveys. The best-fitting Schechter function for the total HIMF has a low-mass slope parameter alpha = -1.30 and a knee mass log(Ms) = 9.86 and a normalization phi_s = 0.00658. This gives the cosmic HI abundance omega_HI= 0.000454. We find that a double Schechter function with the same slope alpha better describes our HIMF, and the two different knee masses are log(Ms1) = 9.96 and log(Ms2) = 9.65. We verify that the measured HIMF is marginally affected by the choice of distance estimates. The effect of cosmic variance is significantly suppressed by combining the three surveys and it provides a unique opportunity to obtain an unbiased estimate of the HIMF in the local universe., Comment: 10 pages, 7 figures, submitted to A&A

In this work we analyze the proposed relation between ADFs and ionized masses in planetary nebulae. For this, we have collected from the literature the ADFs and other parameters such as heliocentric distances, H$\beta$ luminosities, logarithmic reddening correction at H$\beta$, c(H$\beta$), electron densities and others and we calculated the ionized mass for a sample of 132 PNe, 27 of which possess a binary central star (14 are close binaries). In addition the distribution of these objects in the Galaxy is analyzed. The ionized masses were calculated considering two different electron densities, the one provided by the [S II] density sensitive lines ratio and the one provided by the [Cl III] lines ratio. No relation was found between ionized masses and ADFs for this sample, although it is confirmed than the PNe with the largest ADFs correspond in general to objects with a close binary central star, although it is important to say that about 20 percent of these objects have an ADF larger than 5 but smaller than 10. Therefore a PN having a close binary central star does not necessarily exhibit an extremely large ADF. We also have searched for possible relations between the ADFs and the stellar atmospheres, divided in H-rich and H-poor stars. No particular relation was found. Interestingly, several PNe with a [WR] H-poor CSPN present an ADF larger than 10, but so far they have not been reported as having a binary central star., Comment: 19 pages, 7 figures, accepted in MNRAS

Based on the Gaia Data Release 3 and APOGEE datasets, we investigate the kinematic differences between young stellar objects (YSOs) and their parent clouds in five nearby star-forming regions. Overall, the 1D velocity differences between Class II YSOs and their parent molecular cloud range from [0, 1.4] km/s. In feedback environments dominated by outflows, massive stars, and supernova feedback, the corresponding velocity differences range from [0, 1.4] km/s, [0.1, 0.4] km/s, and [0.1, 1] km/s, respectively. These results indicate that YSO kinematics are not significantly affected by these different types of feedback environment. Additionally, compared to the Class II YSOs, Class III YSOs have slightly larger velocities and dispersions., Comment: 19 pages, 17 figures, accepted by ApJS

Dozens of B-type hypervelocity stars (HVSs) moving faster than the Galactic escape speed have been discovered in the Galactic halo and are produced most likely by the supermassive black hole (SMBH) at the Galactic Center (GC). However, the velocity distribution and in particular the deficit of the HVSs above 700 km/s is seriously inconsistent with the expectations of the present models. Here we show that the high-velocity deficit is due to the deficiency in close interactions of stars with the SMBH, because an orbiting intermediate-mass black hole (IMBH) of about 15,000 Solar mass kicked away slowly approaching stars 50-250 million years ago. The SMBH-IMBH binary formed probably after the merger of the Galaxy with the Gaia-Sausage-Enceladus (GSE) dwarf galaxy, and coalesced about 10 million years ago. Afterwards, HVSs with speed up to above 3000 km/s are produced by binary tidal disruptions and the counterparts formed the S-star cluster at the GC., Comment: 34 pages, 13 figures, 1 table, submitted on 2024 January 15

We determine the spectroscopic properties of ~1000 ostensibly star-forming galaxies at redshifts (z=4-10) using prism spectroscopy from JWST/NIRSpec. With rest-wavelength coverage between Lya and [S II] in the optical, we stack spectra as a function of nebular conditions, and compare UV spectral properties with stellar age. This reveals UV lines of N III], N IV], C III], C IV, He II, and O III] in the average high-z galaxy. All UV lines are more intense in younger starbursts. We measure electron temperatures from the collisionally excited [O III] line ratios, finding Te=18000-22000 K for the O++ regions. We also detect a significant nebular Balmer Jump from which we estimate only Te=8000-13000 K. Accounting for typical temperature offsets between zones bearing doubly and singly ionized oxygen, these two temperatures remain discrepant by around 40%. We use the [O III] temperatures to estimate abundances of carbon, nitrogen, and oxygen. We find that log(C/O) is consistently ~-1, with no evolution of C/O with metallicity or stellar age. The average spectra are mildly enhanced in Nitrogen, with higher N/O than low-z starbursts, but are less enhanced than samples of high-z galaxies with visible UV N III] and N IV]. Whatever processes produce the N-enhancement in the individual galaxies must also be ongoing, at lower levels, in the median galaxy in the early Universe. The strongest starbursts are a source of significant ionizing emission: ionizing photon production efficiencies reach 10^25.7 Hz/erg, and show multiple signatures of high Lyman continuum escape, including Mg II escape fractions nearing 100%, significant deficits in [S II] emission, high degrees of ionization, and blue UV colors., Comment: Submitted to the ApJ. 23 pages, 10 figures, 8 tables, 8 authors, 7 sections, ~3MB, one world. Comments welcome

We infer the origin channels of hierarchical mergers observed in the LIGO-Virgo-KAGRA (LVK) O1, O2, and O3 runs using a hierarchical Bayesian analysis under a parametric population model. By assuming the active galactic nucleus (ANG) disk and nuclear star cluster (NSC) channels, we find that NSCs likely dominate the hierarchical merger rate in the universe, corresponding to a fraction of $f_{\rm NSC}=0.87_{-0.29}^{+0.10}$ at 90\% credible intervals in our fiducial model; AGN disks may contribute up to nearly half of hierarchical mergers detectable with LVK, specifically $f_{\rm det,AGN}=0.34_{-0.26}^{+0.38}$. We investigate the impact of the escape speed, along with other population parameters on the branching fraction, suggesting that the mass, mass ratio, and spin of the sources play significant roles in population analysis. We show that hierarchical mergers constitute at least $\sim$$10\%$ of the gravitational wave events detected by LVK during the O1-O3 runs. Furthermore, we demonstrate that it is challenging to effectively infer detailed information about the host environment based solely on the distribution of black hole merger parameters if multiple formation channels are considered., Comment: 11 pages, 2 figures, 2 tables, and comments are welcome

The Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) reveals complex nested morphological and kinematic features of molecular outflows through the CO (J = 2 - 1) and SiO (J = 5 - 4) emission. We characterize the jet and outflow kinematics of the ALMASOP sample in four representative sources (HOPS 10, 315, 358, and G203.21-11.20W2) through channel maps and position-velocity diagrams (PVDs) parallel and transverse to the outflow axes. The combined CO and SiO emission exhibits the coexistence of the conventional extremely-high-velocity (EHV) jets and shell-like low-velocity (LV) cavity walls and new features. More complex, nested bubble-like and filamentary structures in the images and channel maps, triangle-shaped regions near the base of the parallel PVDs, and regions composed of rhombus/oval shapes in the transverse PVDs, are also evident. Such features find natural explanations within the bubble structure of the unified model of jet, wind, and ambient medium. The reverse shock cavity is revealed on the PVD base regions, and other features naturally arise within the dynamic postshock region of magnetic interaction. The finer nested shells observed within the compressed wind region reveal previously unnoticed shocked emission between the jet and the conventional large cavity walls. These pseudopulse-produced filamentary features connect to the jet-like knotty blobs, creating an impression of episodicity in mass ejection. SiO emission is enhanced downstream of the reverse shock boundary, with jet-like excitation conditions. Combined, these observed features reveal the extended structures induced by the magnetic interplay between a jet-bearing magnetized wide-angle wind and its ambient magnetized surrounding medium., Comment: 27 pages, 11 figures, accepted by ApJ

It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, James Webb Space Telescope (JWST) have released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift ($z>7.1$) galaxies with strong [OIII] ($\lambda=4959$ \AA \,and $5007$ \AA \,in the rest frame) emission lines to constraint the evolution of the fine structure constant ($\alpha$). With the spectra from two galaxies at redshifts of $7.19$ and $8.47$, the deviation of $\alpha$ to its fiducial value is found to be as small as $0.44^{+8.4+1.7}_{-8.3-1.7} \times 10^{-4}$ and $-10.0^{+18+1.5}_{-18-1.5} \times 10^{-4}$, respectively (the first error is statistical and the latter is systematic). The combination of our results with the previous data reveals that $\frac{1}{\alpha} \frac{d \alpha}{dt} = 0.30^{+4.5}_{-4.5} \times 10^{-17}~{\rm yr^{-1}}$. Clearly, there is no evidence for a cosmic evolution of $\alpha$. The prospect of further constraining the time evolution of $\alpha$ is also discussed. The scalar field of dark energy is hypothesized to drive the acceleration of the universe's expansion through an interaction with the electromagnetic field. By integrating the observational data of the fine-structure constant variation, $\frac{\Delta\alpha}{\alpha}(z)$, we have established a stringent upper limit on the coupling strength between dark energy and electromagnetism. Our analysis yields $\zeta \leq 3.92 \times 10^{-7}$ at the 95\% confidence level, representing the most stringent bound to date.

We have developed a new regression technique, the maximum likelihood (ML)-based method and its variant, the KS-test based method, designed to obtain unbiased regression results from typical astronomical data. A normalizing flow model is employed to automatically estimate the unobservable intrinsic distribution of the independent variable as well as the unobservable correlation between uncertainty level and intrinsic value of both independent and dependent variables from the observed data points in a variational inference based empirical Bayes approach. By incorporating these estimated distributions, our method comprehensively accounts for the uncertainties associated with both independent and dependent variables. Our test on both mock data and real astronomical data from PHANGS-ALMA and PHANGS-JWST demonstrates that both the ML based method and the KS-test based method significantly outperform the existing widely-used methods, particularly in cases of low signal-to-noise ratios. The KS-test based method exhibits remarkable robustness against deviations from underlying assumptions, complex intrinsic distributions, varying correlations between uncertainty levels and intrinsic values, inaccuracies in uncertainty estimations, outliers, and saturation effects. We recommend the KS-test based method as the preferred choice for general applications, while the ML based method is suggested for small samples with sizes of $N < 100$. A GPU-compatible Python implementation of our methods, nicknamed ``raddest'', will be made publicly available upon acceptance of this paper., Comment: 22 pages, 16 + 3 figures, 1 table; submitted to ApJ; comments welcome

The rovibrational level populations, and subsequent emission in various astrophysical environments, is driven by inelastic collision processes. The available rovibrational rate coefficients for water have been calculated using a number of approximations. We present a numerically exact calculation for the rovibrational quenching for all water vibrational modes due to collisions with atomic hydrogen. The scattering theory implements a quantum close-coupling (CC) method on a high level ab initio six-dimensional (6D) potential energy surface (PES). Total rovibrational quenching cross sections for excited bending levels were compared with earlier results on a 4D PES with the rigid-bender close-coupling (RBCC) approximation. General agreement between 6D-CC and 4D-RBCC calculations are found, but differences are evident including the energy and amplitude of low-energy orbiting resonances. Quenching cross sections from the symmetric and asymmetric stretch modes are provided for the first time. The current 6D-CC calculation provides accurate inelastic data needed for astrophysical modeling., Comment: 20 pages, 5 figures

Stellar-driven galactic winds are multiphase outflows of energy and matter connecting the interstellar and circumgalactic media (CGM) with the intergalactic medium. Galactic winds contain a hot and diffuse phase detected in X-rays, and a cold and dense phase detected via emission and absorption lines from the ions populating the outflow. The ion production within galactic winds largely depends on the background UV radiation field produced by star formation, and this in turn depends on the age of the starburst, the gas metallicity, the proximity of the outflowing gas to the central star-forming regions. Our study probes the influence of the proximity of wind-cloud systems to the UV background source, and the effects of magnetic fields on the N V ion production through the analysis of synthetic column densities and spectral lines. We utilise magnetohydrodynamical simulations to study weakly-magnetised wind-cloud systems, and extract synthetic spectral lines with Trident and yt. Our simulations indicate that magnetic fields transverse to the wind have a shielding effect on dense gas, producing broader N V absorption lines. Also, a weak (distant) UV background produces N V only in the outer cloud layers with no spectral signature, while a strong (nearby) UV background produces it in the cloud core with a narrow spectral line. Overall, transverse magnetic fields and a UV radiation at 50 kpc produce the stronger N V spectral lines., Comment: 5 pages, 1 figure, accepted for publication in the International Astronomical Union Proceedings Series (IAU General Assembly 2024)

Recently, the temporal evolution of the angles characterizing the spatial configuration of the jet in the supermassive black hole M87$^\ast$ was measured exhibiting a precessional pattern around the hole's spin axis. It would be due to the dragging induced by the fact that the hole's external spacetime is described by the Kerr metric. Here, it is shown that the Lense-Thirring orbital precessions of a test particle moving about a rotating massive object, calculated perturbatively to the first post-Newtonian order, are able to fully reproduce all the measured features of the jet axis of M87$^\ast$. In particular, by assuming that the latter is aligned with the angular momentum of the accretion disk, modelled as an effective particle moving along a circular orbit, the condition that the absolute value of the predicted Lense-Thirring precessional frequency of the disk agrees with the measured value of $0.56\pm 0.02$ radians per year of the jet's one is satisfied for a range of physically meaningful values of the hole's spin parameter, close to unity, and of the effective disk radius, of the order of just over a dozen gravitational radii. Relying upon such assumptions and results, it is possible to predict that the angle between the hole's spin axis and the jet's one stays constant over the years amounting to $1.16^\circ$, in agreement with its measured value of $1.25^\circ\pm 0.18^\circ$. Furthermore, also the temporal pattern and the amplitudes of the time series of the jet's angles are reproduced by the aforementioned Lense-Thirring precessional model., Comment: Latex2e, 14 pages, no tables, 6 figures. Reference added. Some minor changes made

Changing-look active galactic nuclei (CLAGNs) show the appearance and disappearance of broad emission lines in their UV/optical spectra on timescales of months to decades. Here, we investigate how CL transitions depend on several AGN parameters such as accretion rate, obscuration properties and black hole mass. We study a sample of 20 nearby optically-identified CLAGNs from the BAT AGN Spectroscopic Survey (BASS), using quasi-simultaneous optical and X-ray observations taken in the last $\sim 40$ years. We find that for all CLAGNs, the transition is accompanied by a change in Eddington ratio. The CL transitions are not associated with changes in the obscuration properties of the AGN. CLAGNs are found to have a median Eddington ratio lower than the AGNs in the BASS sample in which CL transitions were not detected. The median of the transition Eddington ratio (Eddington ratio at which AGN changes its state) is found to be $\sim 0.01$ for type 1 $\leftrightarrow$ 1.8/1.9/2 transition, which is consistent with the hard $\leftrightarrow$ soft state transition in black hole X-ray binaries. Most CL events are constrained to occur within 3-4 years, which is considerably shorter than the expected viscous timescale in AGN accretion disk. The transitions of the optical CLAGNs studied here are likely associated to state changes in the accretion flow, possibly driven by disk-instability., Comment: Accepted for publication in Astronomy & Astrophysics

By observing binary black hole (BBH) mergers out to the edge of the Universe, next-generation (XG) ground-based gravitational-wave (GW) detectors like Cosmic Explorer and Einstein Telescope will map the BBH merger rate across all of cosmic history. This merger rate traces the formation rate of their progenitor stars convolved with a delay time distribution. Given theoretically-motivated priors on the delay time distribution, we show how XG observations can measure the BBH progenitor formation rate, probing the star formation rate (SFR) up to $z > 15$. However, the progenitor formation rate does not directly give a measurement of the SFR, but rather a combination of the SFR and its metallicity distribution as a function of redshift. Fortunately, the metallicity-dependence of BBH formation likely varies as a function of BBH mass and/or formation channel. We find that if different BBH subpopulations with distinct metallicity biases can be identified, comparing their rates as a function of redshift yields a simultaneous measurement of the SFR and its metallicity distribution. Given optimistic theoretical priors and one year of observation, this may provide a $\sim10\%$ measurement of the SFR at its peak and a 0.2 dex (0.7 dex) measurement of the median metallicity out to $z = 10$ ($z = 15$) at 90\% credibility, although the uncertainties scale with theoretical uncertainties on BBH delay times and formation efficiencies., Comment: Invited article for CQG focus issue "Focus on the Science Case for Next Generation (XG) Ground-Based Gravitational Wave Detectors." Submitted on Sep 4, 2024. Comments welcome!

Jets launched by supermassive black holes transport relativistic leptons, magnetic fields, and atomic nuclei from the centres of galaxies to their outskirts and beyond. These outflows embody the most energetic pathway by which galaxies respond to their Cosmic Web environment. Studying black hole feedback is an astrophysical frontier, providing insights on star formation, galaxy cluster stability, and the origin of cosmic rays, magnetism, and heavy elements throughout the Universe. This feedback's cosmological importance is ultimately bounded by the reach of black hole jets, and could be sweeping if jets travel far at early epochs. Here we present the joint LOFAR-uGMRT-Keck discovery of a black hole jet pair extending over $7$ megaparsecs -- the largest galaxy-made structure ever found. The outflow, seen $7.5$ gigayears into the past, spans two-thirds of a typical cosmic void radius, thus penetrating voids at ${\sim}95\%$ probability. This system demonstrates that jets can avoid destruction by magnetohydrodynamical instabilities over cosmological distances, even at epochs when the Universe was 15 to 7 times denser than it is today. Whereas previous record-breaking outflows were powered by radiatively inefficient active galactic nuclei, this outflow is powered by a radiatively efficient active galactic nucleus, a type common at early epochs. If, as implied, a population of early void-penetrating outflows existed, then black hole jets could have overwritten the fields from primordial magnetogenesis. This outflow shows that energy transport from supermassive black holes operates on scales of the Cosmic Web and raises the possibility that cosmic rays and magnetism in the intergalactic medium have a non-local, cross-void origin., Comment: 30 pages, 10 figures, 1 table, published in Nature. This arXiv version pre-dates the peer review process

We present JWST/NIRSpec integral field spectroscopic (IFS) observations of the \Lyalpha emitter CR7 at z ~ 6.6, observed as part of the GA-NIFS program. Using low-resolution PRISM (R ~ 100) data, we confirm a bright \Lyalpha emitter, and a diffuse \Lyalpha halo extending up to 3 kpc from the peak of ionized emission, both of them associated to the most massive, UV bright galaxy in the system (CR7-A). We confirm the presence of two additional UV-bright satellites (CR7-B and CR7-C) detected at projected distances of 6.4 and 5.2 kpc from the primary source. We perform SED fitting of the low-resolution data and revealed an inverted star formation history between two satellites at early epochs and a spatially resolved anti-correlation of the gas-phase metallicity and the star formation rate density, likely driven by the gas exchange among the satellites, favouring the merger scenario for CR7. From the high-resolution G395H (R ~ 2700) data, we discover at least three additional companions mainly traced by the \OIIIL emission line, although they are not detected in continuum. We disentangle the kinematics of the system and reveal extended ionised emission linking the main galaxy and the satellites. We spatially resolve the \OIIIL, \OIII[4363], and \Hgamma emission lines and use a diagnostic diagram tailored to high-z systems to reveal tentative evidence of AGN ionisation across the main galaxy (CR7-A) and the N-E companion (CR7-B). Moreover, we detect an unresolved blue-shifted outflow from one of the satellites and present first evidence for a redshifted outflow from the main galaxy. Finally, we compute resolved electron temperature (T$_e \sim 1.6 \times 10^4$ K) and metallicity maps (log(Z/\zsun) from --0.8 to --0.5), and provide insights on how the physical properties of the system evolved at earlier epochs., Comment: 17 pages, 16 figures, submitted to A&A

The nature of dark matter is poorly constrained on subgalactic scales. Alternative models to cold dark matter, such as warm dark matter or self-interacting dark matter, could produce very different dark haloes on these scales. One of the few known dark haloes smaller than a galaxy was discovered in the triple source plane strong lens system J0946+1006. Previous studies have found that this structure is much more concentrated than expected in $\Lambda$CDM, but have assumed the dark halo is at the same redshift as the main deflector ($z_{\rm main}=0.222$). In this paper, we fit for the redshift of this dark halo. We reconstruct the first two sources in the system using a forward modelling approach, allowing for additional complexity from multipole perturbations. We find that the perturber redshift is $z_{\rm halo} = {0.207}^{+0.019}_{-0.019}$, and lower bounds on the evidence strongly prefer a subhalo over a line-of-sight structure. Whilst modelling both background sources does not improve constraints on the redshift of the subhalo, it breaks important degeneracies affecting the reconstruction of multipole perturbations. We find that the subhalo is a more than $5\sigma$ outlier from the $\Lambda$CDM $v_{\rm max}$-$r_{\rm max}$ relation and has a steep profile with an average slope of $\gamma_{\rm 2D} = {-1.81}^{+0.15}_{-0.11}$ for radii between $0.75-1.25$ kpc. This steep slope might indicate dark matter self-interactions causing the subhalo to undergo gravothermal collapse; such collapsed haloes are expected to have $\gamma_{\rm 2D} \approx -2$., Comment: 16 pages, 10 figures, 2 tables

In this paper, we developed a spectral emulator based on the Mapping Nearby Galaxies at Apache Point Observatory Stellar Library (MaStar) and a grouping optimization strategy to estimate effective temperature (T_eff), surface gravity (log g), metallicity ([Fe/H]) and the abundance of alpha elements with respect to iron ([alpha/Fe]) for O-M-type stars within the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low-resolution spectra. The primary aim is to use a rapid spectral-fitting method, specifically the spectral emulator with the grouping optimization strategy, to create a comprehensive catalog for stars of all types within LAMOST, addressing the shortcomings in parameter estimations for both cold and hot stars present in the official LAMOST AFGKM-type catalog. This effort is part of our series of studies dedicated to establishing an empirical spectral library for LAMOST. Experimental results demonstrate that our method is effectively applicable to parameter prediction for LAMOST, with the single-machine processing time within $70$ hr. We observed that the internal error dispersions for T_eff, log g, [Fe/H], and [alpha/Fe] across different spectral types lie within the ranges of $15-594$ K, $0.03-0.27$ dex, $0.02-0.10$ dex, and $0.01-0.04$ dex, respectively, indicating a good consistency. A comparative analysis with external data highlighted deficiencies in the official LAMOST catalog and issues with MaStar parameters, as well as potential limitations of our method in processing spectra with strong emission lines and bad pixels. The derived atmospheric parameters as a part of this work are available at https://nadc.china-vo.org/res/r101402/ ., Comment: 34 pages, 28 Figures, published in ApJS

Understanding the circumgalactic medium (CGM) distribution of galaxies is the key to revealing the dynamical exchange of materials between galaxies and their surroundings. In this work, we use DESI EDR dataset to investigate the cool CGM of galaxies ($0.3 10.0$, the EW(Mg II) at the minor axis is largely suppressed with respect to low mass galaxies. This suggests that the competing processes, such as stellar feedback and gravity, play a key role in shaping the distribution of outflowing gas., Comment: 20 pages, 17 figures. Submitted to ApJ. Comments are welcome

Circumstellar OH maser lines are useful for studying the dynamics of the circumstellar envelope (CSE) around evolved stars. This study aims to identify CSEs around cold stars bf, which exhibit deviations from the spherical expansion, by comparing the velocity ranges of the OH main lines (1665/1667 MHz) with those of the satellite line (1612 MHz), using a database of circumstellar OH maser sources. We performed this comparison for 377 circumstellar OH maser sources. In addition, using infrared two-color diagrams, we examined the evolutionary stages and infrared properties of objects showing velocity excess (velocity excess means the detection of the main lines outside the velocity range of the satellite line). A periodicity analysis of the WISE light curves was also carried out. As a result of the velocity range comparison, eight circumstellar OH maser sources were found to exhibit velocity excess. The infrared colors of these objects match those of post-AGB stars. Periodic variations were observed in the WISE light curves of five of these eight objects. The results suggest that examining velocity excess of the main lines relative to the satellite line is scientifically significant because mainline masers probe the CSE dynamics over a broader range of evolutionary stages compared to the 22.235 GHz H${_2}$O maser line. Additionally, during the post-AGB phase, the emission regions of the mainline and 22.235 GHz H${_2}$O masers may overlap in a CSE, whereas they originate from different regions during the AGB phase., Comment: 48 pages, 24 figures, Accepted for publication in ApJ

We critically assess the impact of significant dipole and large-scale anisotropies on galaxy clustering signals, with a focus on radio continuum surveys. Our study reveals that these anisotropies -- resulting from intrinsic cosmological effects and/or observational systematics -- profoundly influence the two-point correlation function (2PCF) and angular power spectrum ($C_\ell$). Notably, large-scale anisotropies can obscure or simulate non-Gaussianity signals, complicating the extraction of precise cosmological information. The results emphasize that it is crucial to address systematics and rigorously mask the dipole and its surrounding multipoles to obtain accurate cosmological constraints. This approach is essential for extracting cosmological results from clustering signals, particularly for future surveys such as SKA, DESI, and LSST, to ensure the precision and reliability of cosmological analyses., Comment: 5 pages, 2 figures

Supernova remnants (SNRs) can exert strong influence on molecular clouds (MCs) through interaction by shock wave and cosmic rays. In this paper, we present our mapping observation of HCO+ and HCN 1-0 lines towards 13 SNRs interacting with MCs, together with archival data of CO isotopes. Strong HCO+ emission is found in the fields of view (FOVs) of SNRs W30, G9.7-0.0, Kes 69, 3C 391, 3C 396, W51C, HC 40, and CTB109 in the local-standard-of-rest (LSR) velocity intervals in which they are suggested to show evidence of SNR-MC interaction. We find an incomplete 12CO shell surrounding G9.7-0.0 with an expanding motion. This shell may be driven by the stellar wind of the SNR progenitor. We also find an arc of 12CO gas spatially coincident with the northwestern radio shell of Kes 69. As for the HCO+ line emission, SNRs 3C 391 and W51C exhibit significant line profile broadening indicative of shock perturbation, and CTB109 exhibits a possible blue-shifted line wing brought by shock interaction. We do not find significant variation of the I(HCO+)/I(HCN) line ratio between broad-line and narrow-line regions, among different SNRs, and between MCs associated with SNRs and typical Galactic MCs. Therefore, we caution on using the I(HCO+)/I(HCN) line ratio as a diagnostic of SNR feedback and CR ionization. We also estimate the N(HCO+)/N(CO) abundance ratio in 11 regions towards the observed SNRs, but they show little difference from the typical values in quiescent MCs, possibly because N(HCO+)/N(CO) is not an effective tracer of CR ionization., Comment: 19 pages, 8 figures, accepted for publication in ApJ

Fast radio bursts (FRBs) are transient radio events with millisecond-scale durations, and debated origins. Collisions between planetesimals and neutron stars have been proposed as a mechanism to produce FRBs; the planetesimal strength, size and density determine the time duration and energy of the resulting event. One source of planetesimals is the population of interstellar objects (ISOs), free-floating objects expected to be extremely abundant in galaxies across the Universe as products of planetary formation. We explore using the ISO population as a reservoir of planetesimals for FRB production, finding that the expected ISO-neutron star collision rate is comparable with the observed FRB event rate. Using a model linking the properties of planetesimals and the FRBs they produce, we further show that observed FRB durations are consistent with the sizes of known ISOs, and the FRB energy distribution is consistent with the observed size distributions of Solar System planetesimal populations. Finally, we argue that the rate of ISO-neutron star collisions must increase with cosmic time, matching the observed evolution of the FRB rate. Thus, ISO-neutron star collisions are a feasible mechanism for producing FRBs., Comment: Accepted for publication in ApJ (6 pages, 1 figure 1 table)

Sulfur dioxide (SO2) is a sulfur-containing molecule expected to exist as a solid in the interstellar medium (ISM). In this study, we performed laboratory experiments and computational analyses on the surface reactions of solid SO2 with hydrogen atoms on amorphous solid water (ASW) at low temperatures. After 40 min of exposure of SO2 deposited on ASW to H atoms, approximately 80% of the solid SO2 was lost from the substrate at 10-40 K, and approximately 50% even at 60 K, without any definite detection of reaction products. Quantum chemical calculations suggest that H atoms preferentially add to the S atom of solid SO2, forming the HSO2 radical. Further reactions of the HSO2 radical with H atoms result in the formation of several S-bearing species, including HS(O)OH, the S(O)OH radical, HO-S-OH, HS-OH, and H2S. In codeposition experiments involving H and SO2, we confirmed the formation of H2S, HS(O)OH, and/or HO-S-OH. However, the yields of these S-bearing species were insufficient to account for the complete loss of the initial SO2 reactant. These findings suggest that some products desorbed into the gas phase upon formation. This study indicates that a portion of SO2 in ice mantles may remain unreacted, avoiding hydrogenation, while the remainder is converted into other species, some of which may be subject to chemical desorption., Comment: Accepted for publication in ApJ

We carried out a project involving the systematic analysis of microlensing data from the Korea Microlensing Telescope Network survey. The aim of this project is to identify lensing events with complex anomaly features that are difficult to explain using standard binary-lens or binary-source models. Our investigation reveals that the light curves of microlensing events KMT-2021-BLG-0284, KMT-2022-BLG-2480, and KMT-2024-BLG-0412 display highly complex patterns with three or more anomaly features. These features cannot be adequately explained by a binary-lens (2L1S) model alone. However, the 2L1S model can effectively describe certain segments of the light curve. By incorporating an additional source into the modeling, we identified a comprehensive model that accounts for all the observed anomaly features. Bayesian analysis, based on constraints provided by lensing observables, indicates that the lenses of KMT-2021-BLG-0284 and KMT-2024-BLG-0412 are binary systems composed of M dwarfs. For KMT-2022-BLG-2480, the primary lens is an early K-type main-sequence star with an M dwarf companion. The lenses of KMT-2021-BLG-0284 and KMT-2024-BLG-0412 are likely located in the bulge, whereas the lens of KMT-2022-BLG-2480 is more likely situated in the disk. In all events, the binary stars of the sources have similar magnitudes due to a detection bias favoring binary source events with a relatively bright secondary source star, which increases detection efficiency., Comment: 9 pages, 9 figures

The relationship between galaxies and their supermassive black holes (SMBHs) is an area of active research. One way to investigate this is to compare parsec-scale jets formed by SMBHs with the projected shape of their kiloparsec-scale host galaxies. We analyse Very Long Baseline Interferometry (VLBI) images of Active Galactic Nuclei (AGN) and optical images of their host galaxies. We compare the inner-jet position angle in VLBI-detected radio sources with the optical shapes of galaxies as measured by several large optical surveys. In total 6273 galaxy-AGN pairs were found. We carefully account for the systematics of the cross-matched sources and find that Dark Energy Spectroscopic Instrument Legacy Imaging Surveys data (DESI LS) is significantly less affected by them. Using DESI LS, with which 5853 galaxy-AGN pairs were cross-matched, we find a weak but significant alignment signal (with a p-value $\leqslant$ 0.01) between the parsec-scale AGN jet and the kpc projected minor axis of the optical host galaxy in sources with measured spectroscopic redshifts. Our results show that the observed source properties are connected over 3 orders of magnitude in scale. This points towards an intimate connection between the SMBH, their host galaxies and their subsequent evolution., Comment: 37 pages, 15 figures, published in Nature Astronomy: https://www.nature.com/articles/s41550-024-02407-4

The formation of supermassive black holes (SMBHs) in the early Universe is a subject of significant debate. In this study, we examine whether non-evaporating primordial black holes (PBHs) can offer a solution. We establish initial constraints on the range of PBH masses that correspond to Hawking radiation (HR) effective temperatures in the range needed to avoid the fragmentation of primordial gas into smaller, stellar-mass black holes. We also investigate the specific intensity of the HR from non-evaporating PBHs and compare it with the critical radiation needed for direct collapse black holes (DCBHs). We show that HR from non-evaporating PBHs cannot serve as the heating mechanism to facilitate the formation of the seeds for the SMBHs we observe in the high-redshift Universe unless, perhaps, the PBHs within the relevant mass range comprise a significant fraction of dark matter and are significantly clustered towards the center of the primordial halo., Comment: 16 pages, 6 figures. Project based on an undergradute thesis, to be submitted soon to the Open Journal of Astrophysics. Comments welcome

The history of gas assembly in early galaxies is reflected in their complex kinematics. While a considerable fraction of galaxies at z~5 are consistent with rotating disks, current studies indicate that the dominant galaxy assembly mechanism corresponds to mergers. Despite the important progress, the dynamical classification of galaxies at these epochs is still limited by observations' resolution. We present a detailed morphological and kinematic analysis of the far-infrared bright main sequence galaxy HZ10 at z=5.65, making use of new high-resolution ($\lesssim0.3$") [CII] 158$\mu$m ALMA and rest-frame optical JWST/NIRSpec observations. These observations reveal a previously unresolved complex morphology and kinematics of the HZ10. We confirm that HZ10 is not a single galaxy but consists of at least three components in close projected separation along the east-to-west direction. We find a [CII] bright central component (C), separated by 1.5 and 4 kpc from the east (E) and west (W) components, respectively. Our [CII] observations resolve the HZ10-C component resulting in a velocity gradient, produced by either rotation or a close-in merger. We test the rotating disk possibility using DysmalPy kinematic modeling and propose three dynamical scenarios for the HZ10 system: (i) a double merger, in which the companion galaxy HZ10-W merges with the disturbed clumpy rotation disk formed by the HZ10-C and E components; (ii) a triple merger, where the companion galaxies, HZ10-W and HZ10-E, merge with the rotation disk HZ10-C; and (iii) a quadruple merger, in which the companion galaxies HZ10-W and HZ10-E merge with the close double merger HZ10-C. Comparing [CII] with JWST/NIRSpec data, we find that [CII] emission closely resembles the broad [OIII] 5007{\AA} emission. The latter reflects the interacting nature of the system and suggests that ionized and neutral gas phases in HZ10 are well mixed., Comment: Submitted to A&A, 16 pages, 17 figures, 1 table

As globular clusters (GCs) orbit the Milky Way, their stars are tidally stripped forming tidal tails that follow the orbit of the clusters around the Galaxy. The morphology of these tails is complex and shows correlations with the phase of the orbit and the orbital angular velocity, especially for GCs on eccentric orbits. Here, we focus on two GCs, NGC 1261 and NGC 1904, that have potentially been accreted alongside Gaia-Enceladus and that have shown signatures of having, in addition of tidal tails, structures formed by distributions of extra-tidal stars that are misaligned with the general direction of the clusters' respective orbits. To provide an explanation for the formation of these structures, we make use of spectroscopic measurements from the Southern Stellar Stream Spectroscopic Survey ($S^5$) as well as proper motion measurements from Gaia's third data release (DR3), and apply a Bayesian mixture modeling approach to isolate high-probability member stars. We recover extra-tidal features similar to those found in Shipp et al. (2018) surrounding each cluster. We conduct N-body simulations and compare the expected distribution and variation in the dynamical parameters along the orbit with those of our potential member sample. Furthermore, we use Dark Energy Camera (DECam) photometry to inspect the distribution of the member stars in the color-magnitude diagram (CMD). We find that the potential members agree reasonably with the N-body simulations and that the majority of them follow a simple stellar population-like distribution in the CMD which is characteristic of GCs. In the case of NGC 1904, we clearly detect the tidal debris escaping the inner and outer Lagrange points which are expected to be prominent when at or close to the apocenter of its orbit. Our analysis allows for further exploration of other GCs in the Milky Way that exhibit similar extra-tidal features.

Context. A major challenge in astrophysics is classifying galaxies by their activity. Current methods often require multiple diagnostics to capture the full range of galactic activity. Furthermore, overlapping excitation sources with similar observational signatures complicate the analysis of a galaxy's activity. Aims. This study aims to create an activity diagnostic tool that overcomes the limitations of current emission line diagnostics by identifying the underlying excitation mechanisms in mixed-activity galaxies (e.g., star formation, active nucleus, or old stellar populations) and determining the dominant ones. Methods. We use the random forest machine-learning algorithm, trained on three main activity classes -- star-forming, AGN, and passive -- that represent key gas excitation mechanisms. This diagnostic employs four distinguishing features: the equivalent widths of [O iii] ${\lambda}$5007, [N ii] ${\lambda}$6584, H${\alpha}$, and the D4000 continuum break index. Results. The classifier achieves near-perfect performance, with an overall accuracy of ~ 99% and recall scores of ~ 100% for star-forming, ~ 98% for AGN, and ~ 99% for passive galaxies. These exceptional scores allow for confident decomposition of mixed activity classes into the primary gas excitation mechanisms, overcoming the limitations of current classification methods. Additionally, the classifier can be simplified to a two-dimensional diagnostic using the D4000 index and log$_{10}$(EW([O iii])$^{2}$) without significant loss of diagnostic power. Conclusions. We present a diagnostic for classifying galaxies by their primary gas excitation mechanisms and deconstructing the activity of mixed-activity galaxies into these components. This method covers the full range of galaxy activity. Aditionally, D4000 index serves as an indicator for resolving the degeneracy among various activity components., Comment: 19 pages, 16 figures, Accepted for publication in A&A

Observations of the Milky Way and external galaxies support the idea that large-scale magnetic fields are concentrated in galactic disks, with halo magnetic fields at least an order of magnitude weaker. However, very little is known about the transition between the two. We present the discovery of linearly polarized radio emission at the interface between interacting shells of gas within a well-known grouping of high-velocity clouds (HVCs), the Anti-Center Shell. Faraday rotation of diffuse emission and of background extragalactic compact sources demonstrates an enhancement of the field at the interface. This is the clearest observed example of an HVC altering the large-scale magnetic field at the disk-halo interface and is the first image of magnetic field effects in an HVC. These results demonstrate the possibility of future three-dimensional reconstruction of the Galactic magnetic field and showcase the versatility of the Synthesis Telescope at the Dominion Radio Astrophysical Observatory as one of the few existing telescopes which can exploit this new method of probing Galactic magnetism., Comment: Accepted for publication in the Astrophysical Journal Nov. 13, 2024

We combine the power of blind integral field spectroscopy from the Hobby-Eberly Telescope (HET) Dark Energy Experiment (HETDEX) with sources detected by the Low Frequency Array (LOFAR) to construct the HETDEX-LOFAR Spectroscopic Redshift Catalog. Starting from the first data release of the LOFAR Two-metre Sky Survey (LoTSS), including a value-added catalog with photometric redshifts, we extracted 28,705 HETDEX spectra. Using an automatic classifying algorithm, we assigned each object a star, galaxy, or quasar label along with a velocity/redshift, with supplemental classifications coming from the continuum and emission line catalogs of the internal, fourth data release from HETDEX (HDR4). We measured 9,087 new redshifts; in combination with the value-added catalog, our final spectroscopic redshift sample is 9,710 sources. This new catalog contains the highest substantial fraction of LOFAR galaxies with spectroscopic redshift information; it improves archival spectroscopic redshifts, and facilitates research to determine the [O II] emission properties of radio galaxies from $0.0 < z < 0.5$, and the Ly$\alpha$ emission characteristics of both radio galaxies and quasars from $1.9 < z < 3.5$. Additionally, by combining the unique properties of LOFAR and HETDEX, we are able to measure star formation rates (SFR) and stellar masses. Using the Visible Integral-field Replicable Unit Spectrograph (VIRUS), we measure the emission lines of [O III], [Ne III], and [O II] and evaluate line-ratio diagnostics to determine whether the emission from these galaxies is dominated by AGN or star formation and fit a new SFR-L$_{150MHz}$ relationship., Comment: 21 pages, 17 figures, submitted to ApJ