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We recently revealed that bulges and elliptical galaxies broadly define distinct, superlinear relations in the (black hole mass, M bh)–(spheroid stellar mass, M *,sph) diagram or M bh− M *,sph diagram, with the order-of-magnitude lower M bh/ M *,sph ratios in the elliptical galaxies due to major (disc-destroying, elliptical-building) dry mergers. Here, we present a more nuanced picture. Galaxy mergers, in which the net orbital angular momentum does not cancel, can lead to systems with a rotating disc. This situation can occur with either wet (gas-rich) mergers involving one or two spiral galaxies, e.g. NGC 5128, or dry (relatively gas-poor) collisions involving one or two lenticular galaxies, e.g. NGC 5813. The spheroid and disc masses of the progenitor galaxies and merger remnant dictate the shift in the M bh− M *,sph and M bh− R e,sph diagrams. We show how this explains the (previously excluded merger remnant) Sérsic S0 galaxies near the bottom of the elliptical sequence and core-Sérsic S0 galaxies at the top of the bulge sequence, neither of which are faded spiral galaxies. Different evolutionary pathways in the scaling diagrams are discussed. We also introduce two ellicular (ES) galaxy types, explore the location of brightest cluster galaxies and stripped 'compact elliptical' galaxies in the M bh− M *,sph diagram, and present a new merger-built M bh− M *,sph relation which may prove helpful for studies of nanohertz gravitational waves. This work effectively brings into the fold many systems previously considered outliers with either overly massive or undermassive black holes relative to the near-linear M bh− M *,sph 'red sequence' patched together with select bulges and elliptical galaxies. [ABSTRACT FROM AUTHOR]

When strong gravitational lenses are to be used as an astrophysical or cosmological probe, models of their mass distributions are often needed. We present a new, time-efficient automation code for the uniform modeling of strongly lensed quasars with GLEE, a lens-modeling software for multiband data. By using the observed positions of the lensed quasars and the spatially extended surface brightness distribution of the host galaxy of the lensed quasar, we obtain a model of the mass distribution of the lens galaxy. We applied this uniform modeling pipeline to a sample of nine strongly lensed quasars for which images were obtained with the Wide Field Camera 3 of the Hubble Space Telescope. The models show well-reconstructed light components and a good alignment between mass and light centroids in most cases. We find that the automated modeling code significantly reduces the input time during the modeling process for the user. The time for preparing the required input files is reduced by a factor of 3 from ~3 h to about one hour. The active input time during the modeling process for the user is reduced by a factor of 10 from ~10 h to about one hour per lens system. This automated uniform modeling pipeline can efficiently produce uniform models of extensive lens-system samples that can be used for further cosmological analysis. A blind test that compared our results with those of an independent automated modeling pipeline based on the modeling software Lenstronomy revealed important lessons. Quantities such as Einstein radius, astrometry, mass flattening, and position angle are generally robustly determined. Other quantities, such as the radial slope of the mass density profile and predicted time delays, depend crucially on the quality of the data and on the accuracy with which the point spread function is reconstructed. Better data and/or a more detailed analysis are necessary to elevate our automated models to cosmography grade. Nevertheless, our pipeline enables the quick selection of lenses for follow-up and further modeling, which significantly speeds up the construction of cosmography-grade models. This important step forward will help us to take advantage of the increase in the number of lenses that is expected in the coming decade, which is an increase of several orders of magnitude. [ABSTRACT FROM AUTHOR]

Elliptical galaxies with blue optical colours and significant star formation are hypothesised to be major merger remnants of gas-rich spiral galaxies or normal elliptical galaxies with a sudden burst of star formation. We present here a scenario in which blue elliptical galaxies identified in shallow imaging surveys may fail to recover faint features that are indicative of past merger activity using a nearby major merger remnant. Based on deep optical imaging data of the post-merger galaxy, NGC 7252, we demonstrate that the galaxy can appear as an elliptical galaxy if it is observed at higher redshifts. The main body and the low surface brightness merger features found at the outskirts of the galaxy are blue in the optical g − r colour map. We argue that the higher-redshift blue elliptical galaxies discovered in surveys as shallow as the SDSS or DECaLS may be advanced mergers whose defining tidal features fall below the detection limits of the surveys. This should be taken into consideration during the morphological classification of these systems in future and ongoing surveys. [ABSTRACT FROM AUTHOR]

We study the total and baryonic mass distributions of the deflector SDSS J0100+1818 through a full strong lensing analysis. The system is composed of an ultra-massive early-type galaxy at z = 0.581, with a total stellar mass of (1.5 ± 0.3)×1012 M⊙ and a stellar velocity dispersion of (450 ± 40) km s−1, surrounded by ten multiple images of three background sources, two of which are spectroscopically confirmed at z = 1.880. We took advantage of high-resolution HST photometry and VLT/X-shooter spectroscopy to measure the positions of the multiple images and performed a strong lensing study with the software GLEE. We tested different total mass profiles for the lens and modeled the background sources first as point-like and then as extended objects. We successfully predict the positions of the observed multiple images and reconstruct over approximately 7200 HST pixels the complex surface brightness distributions of the sources. We measured the cumulative total mass profile of the lens and find a total mass value of (9.1 ± 0.1)×1012 M⊙, within the Einstein radius of approximately 42 kpc, and stellar-over-total mass fractions ranging from (49 ± 12)%, at the half-light radius (Re = 9.3 kpc) of the lens galaxy, to (10 ± 2)%, in the outer regions (R = 70 kpc). These results suggest that the baryonic mass component of SDSS J0100+1818 is very concentrated in its core and that the lens early-type galaxy (or group) is immersed in a massive dark matter halo, which allows it to act as a powerful gravitational lens, creating multiple images with exceptional angular separations. This is consistent with what has been found in other ultra-high-mass candidates at intermediate redshift. We also measured the physical sizes of the distant sources, resolving them down to a few hundred parsecs. Finally, we quantify and discuss a relevant source of systematic uncertainties on the reconstructed sizes of background galaxies, associated with the adopted lens total mass model. [ABSTRACT FROM AUTHOR]

Residuals between measured galactic radii and those predicted by the Fundamental Plane (FP) are possible tracers of weak lensing magnification. However, observations have shown these to be systematically correlated with the large-scale structure. We use the Horizon-AGN hydrodynamical cosmological simulation to analyse these intrinsic size correlations (ISCs) for both elliptical (early-type) and spiral (late-type) galaxies at |$z$|  = 0.06. We fit separate FPs to each sample, finding similarly distributed radius residuals, λ, in each case. We find persistent λλ correlations over three-dimensional separations |$0.5\hbox{--}17\, h^{-1}\, {\rm {Mpc}}$| in the case of spiral galaxies, at >3σ significance. When relaxing a mass-selection, applied for better agreement with galaxy clustering constraints, the spiral λλ detection strengthens to 9σ; we detect a 5σ density-λ correlation; and we observe intrinsically-large spirals to cluster more strongly than small spirals over scales |${\lesssim}10\, h^{-1}\, {\rm {Mpc}}$| at >5σ significance. Conversely, and in agreement with the literature, we observe lower-mass, intrinsically-small ellipticals to cluster more strongly than their large counterparts over scales |$0.5\hbox{--}17\, h^{-1}\, {\rm {Mpc}}$| at >5σ significance. We model λλ correlations using a phenomenological non-linear size model, and predict the level of contamination for cosmic convergence analyses. We find the systematic contribution to be of similar order to, or dominant over the cosmological signal. We make a mock measurement of an intrinsic, systematic contribution to the projected surface mass density Σ(r), and find statistically significant low-amplitude, positive (negative) contributions from lower-mass spirals (ellipticals), which may be of concern for large-scale (⁠|${\gtrsim}7\, h^{-1}$|  Mpc) measurements. [ABSTRACT FROM AUTHOR]

Using the Lyman Dropout technique, we identify 148 candidate radio sources at z ≳ 4–7 from the 887.5 MHz Australian Square Kilometre Array Pathfinder (ASKAP) observations of the GAMA23 field. About 112 radio sources are currently known beyond redshift z ∼ 4. However, simulations predict that hundreds of thousands of radio sources exist in that redshift range, many of which are probably in existing radio catalogues, but do not have measured redshifts, either because their optical emission is too faint or because of the lack of techniques that can identify candidate high-redshift radio sources (HzRSs). Our study addresses these issues using the Lyman Dropout search technique. This newly built sample probes radio luminosities that are 1–2 orders of magnitude fainter than known radio-active galactic nuclei (AGN) at similar redshifts, thanks to ASKAP's sensitivity. We investigate the physical origin of radio emission in our sample using a set of diagnostics: (i) radio luminosity at 1.4 GHz, (ii) 1.4 GHz to 3.4 μm flux density ratio, (iii) Far-IR detection, (iv) WISE colour, and (v) SED modelling. The radio/IR analysis has shown that the majority of radio emission in the faint and bright end of our sample's 887.5 MHz flux density distribution originates from AGN activity. Furthermore, ∼10 per cent of our sample are found to have a 250 μm detection, suggesting a composite system. This suggests that some high- z radio-AGNs are hosted by SB galaxies in contrast to low- z radio-AGNs, which are usually hosted by quiescent elliptical galaxies. [ABSTRACT FROM AUTHOR]

We use the kinematic data of the stars in eight dwarf spheroidal galaxies to assess whether f(R) gravity can fit the observed profiles of the line-of-sight velocity dispersion of these systems without resorting to dark matter. Our model assumes that each galaxy is spherically symmetric and has a constant velocity anisotropy parameter β and constant mass-to-light ratio consistent with stellar population synthesis models. We solve the spherical Jeans equation that includes the Yukawa-like gravitational potential appearing in the weak field limit of f(R) gravity, and a Plummer density profile for the stellar distribution. The f(R) velocity dispersion profiles depends on two parameters: the scale length ξ−1, below which the Yukawa term is negligible, and the boost of the gravitational field δ > −1. δ and ξ are not universal parameters, but their variation within the same class of objects is expected to be limited. The f(R) velocity dispersion profiles fit the data with a value |$\xi ^{-1}= 1.2^{+18.6}_{-0.9}$| Mpc for the entire galaxy sample. On the contrary, the values of δ show a bimodal distribution that picks at |$\overline{\delta }=-0.986\pm 0.002$| and |$\overline{\delta }=-0.92\pm 0.01$|⁠. These two values disagree at 6σ and suggest a severe tension for f(R) gravity. It remains to be seen whether an improved model of the dwarf galaxies or additional constraints provided by the proper motions of stars measured by future astrometric space missions can return consistent δ's for the entire sample and remove this tension. [ABSTRACT FROM AUTHOR]

Numerical simulations within a cold dark matter (DM) cosmology form haloes whose density profiles have a steep inner slope ('cusp'), yet observations of galaxies often point towards a flat central 'core'. We develop a convolutional mixture density neural network model to derive a probability density function (PDF) of the inner density slopes of DM haloes. We train the network on simulated dwarf galaxies from the NIHAO and AURIGA projects, which include both DM cusps and cores: line-of-sight velocities and 2D spatial distributions of their stars are used as inputs to obtain a PDF representing the probability of predicting a specific inner slope. The model recovers accurately the expected DM profiles: |$\sim 82{{\ \rm per\ cent}}$| of the galaxies have a derived inner slope within ±0.1 of their true value, while |$\sim 98{{\ \rm per\ cent}}$| within ±0.3. We apply our model to four Local Group dwarf spheroidal galaxies and find results consistent with those obtained with the Jeans modelling based code GravSphere : the Fornax dSph has a strong indication of possessing a central DM core, Carina and Sextans have cusps (although the latter with large uncertainties), while Sculptor shows a double peaked PDF indicating that a cusp is preferred, but a core cannot be ruled out. Our results show that simulation-based inference with neural networks provide a innovative and complementary method for the determination of the inner matter density profiles in galaxies, which in turn can help constrain the properties of the elusive DM. [ABSTRACT FROM AUTHOR]

We analyse the bulge/spheroid size–(stellar mass), R e, Sph − M *, Sph, relation and spheroid structural parameters for 202 local (predominantly |$\lesssim 110~\rm Mpc$|⁠) galaxies spanning |$M_*\sim 3\times 10^{9}\!-\!10^{12}~\rm M_{\odot }$| and |$0.1 \lesssim R_\mathrm{e, Sph}\lesssim 32~\rm kpc$| from multicomponent decomposition. The correlations between the spheroid Sérsic index (n Sph), central surface brightness (μ0, Sph), effective half-light radius (R e, Sph), absolute magnitude (⁠|$\mathfrak {M}_\mathrm{Sph}$|⁠), and stellar mass (M *, Sph) are explored. We also investigate the consequences of using different scale radii, |$R_{z,\rm Sph}$|⁠ , encapsulating a different fraction (z , from 0 to 1) of the total spheroid luminosity. The correlation strengths for projected mass densities, Σ z and 〈Σ〉 z , vary significantly with the choice of z. Spheroid size (⁠|$R_\mathrm{z, \rm Sph}$|⁠) and mass (M *, Sph) are strongly correlated for all light fractions z. We find |$\log (R_\mathrm{e,Sph}/\rm kpc) = 0.88\log (M_\mathrm{*,Sph}/\rm M_{\odot })-9.15$| with a small scatter of |$\Delta _{rms} = 0.24~\rm dex$| in the log (R e, Sph) direction. This result is discussed relative to the curved size–mass relation for early-type galaxies due to their discs yielding larger galaxy radii at lower masses. Moreover, the slope of our spheroid size–mass relation is a factor of ∼3, steeper than reported bulge size–mass relations, and with bulge sizes at M *, sph ∼3 × 109 M⊙ which are 2–3 times smaller. Our spheroid size–mass relation present no significant flattening in slope in the low-mass end (⁠|$M_{\rm *,sph}\sim 10^9 - 10^{10}\rm ~M_{\odot }$|⁠). Instead of treating galaxies as single entities, future theoretical and evolutionary models should also attempt to recreate the strong scaling relations of specific galactic components. Additional scaling relations, such as log (n Sph) − log (M *, Sph), log (Σ0, Sph) − log (n Sph), and log (n Sph) − log (R e, Sph), are also presented. Finally, we show that the local spheroids align well with the size-mass distribution of quiescent galaxies at z ∼ 1.25–2.25. In essence, local spheroids and high- z quiescent galaxies appear structurally similar, likely dictated by the virial theorem. [ABSTRACT FROM AUTHOR]

We report the first 5σ detection of H  i 21 cm emission from a star-forming galaxy at redshift z ∼ 1.3 (nearly 9 billion years ago) using upgraded Giant Metrewave Radio Telescope (uGMRT). This is the highest redshift H  i detection in emission from an individual galaxy to date. The emission is strongly boosted by the gravitational lens, an early-type elliptical galaxy, at redshift z ∼ 0.13. The measured H  i mass of the galaxy is |$M_{\rm H\, \small {\rm I}} = (0.90 \pm 0.14 \pm 0.05) \times 10^{10}\, \mathrm{M}_{\odot }$|⁠ , which is almost twice the inferred stellar mass of the galaxy, indicating an extended structure of the H  i gas inside the galaxy. By fitting 2D Gaussian to the H  i signal at the peak of the spectral line, we find the source to be marginally resolved with the position angle consistent with the emission being tangential to the critical curve of the lens mass distribution. This indicates that the solid angle of the approaching H  i line flux comes very close to the inner lens caustic and results in very high magnification. These results, for the first time, demonstrate the feasibility of observing high-redshift H  i in a lensed system with the modest amount of telescope time and open up exciting new possibilities for probing the cosmic evolution of neutral gas with existing and upcoming low-frequency radio telescopes in the near future. [ABSTRACT FROM AUTHOR]

We revisit the viability of the CMSSM, searching for regions of parameter space that yield a neutralino dark matter density compatible with Planck measurements, as well as LHC constraints including sparticle searches and the mass of the Higgs boson, recent direct limits on spin-independent and -dependent dark matter scattering from the LUX-ZEPLIN (LZ) experiment, the indirect constraints from Fermi-LAT and H.E.S.S. on dark matter annihilations to photons in dwarf spheroidal galaxies and the Galactic Centre, and the IceCube limits on muons from annihilations to neutrinos in the Sun. For representative values of tan β and A 0 we map in detail the Planck-compatible strips in CMSSM parameter planes, which exhibit multiple distinctive features for large tan β , A 0 = 0 and μ > 0 , and identify portions of the strips that survive all the phenomenological constraints. We find that the most powerful constraint is that from m h , followed by the LZ limit on spin-independent scattering, whereas sparticle searches at the LHC and indirect dark matter searches are less restrictive. Most of the surviving CMSSM parameter space features a Higgsino-like dark matter particle with a mass ∼ 1000 - 1100 GeV, which could best be probed with future direct searches for dark matter scattering. [ABSTRACT FROM AUTHOR]

Lenticular galaxies (S0s) are formed mainly from the gas stripping of spirals in the cluster. But how S0s form and evolve in the field is still in need of being resolved. Based on spatially resolved observations from the optical Hispanic Astronomical Center in Andalusia 3.5 m telescope with the PPAK Integral Field Spectroscopy instrument and Northern Extended Millimeter Array, we study a dwarf ( M _* < 10 ^9 M _⊙ ) S0, PGC 44685, with triple star-forming regions in the central region, namely, A, B, and C, respectively. In northwest region C, we clearly detect the spectral features of Wolf–Rayet (W-R) stars and quantify the W-R population by stacking spectra with high W-R significance. Most of the molecular gas is concentrated in region C(W-R), and there is diffuse gas around regions A and B. The W-R region possesses the strongest intensities of H α , CO(1–0), and 3 mm continuum, indicating its ongoing violent star formation (gas depletion timescale ≲25 Myr) with tentative hundreds (

We present a stellar dynamical mass measurement of the supermassive black hole in the elliptical (E1) galaxy NGC 3258. Our findings are based on integral field unit spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) observations in narrow-field mode with adaptive optics and the MUSE wide-field mode, from which we extract kinematic information by fitting the Ca ii and Mg b triplets, respectively. Using axisymmetric, three-integral Schwarzschild orbit library models, we fit the observed line-of-sight velocity distributions to infer the supermassive black hole mass, the H -band mass-to-light ratio, the asymptotic circular velocity, and the dark matter halo scale radius of the galaxy. We report a black hole mass of (2.2 ± 0.2) × 10 ^9 M _⊙ at an assumed distance of 31.9 Mpc. This value is in close agreement with a previous measurement from Atacama Large Millimeter/submillimeter Array CO observations. The consistency between these two measurements provides strong support for both the gas dynamical and stellar dynamical methods.

We present 3D magnetohydrodynamic simulations of the fueling of supermassive black holes in elliptical galaxies from a turbulent cooling medium on galactic scales, taking M87* as a typical case. We find that the mass accretion rate is increased by a factor of ∼10 compared with analogous hydrodynamic simulations. The scaling of $\dot{M}\sim {r}^{1/2}$ roughly holds from ∼10 pc to ∼10 ^−3 pc (∼10 r _g ) with the accretion rate through the event horizon being ∼10 ^−2 M _⊙ yr ^−1 . The accretion flow on scales ∼0.03–3 kpc takes the form of magnetized filaments. Within ∼30 pc, the cold gas circularizes, forming a highly magnetized ( β ∼ 10 ^−3 ) thick disk supported by a primarily toroidal magnetic field. The cold disk is truncated and transitions to a turbulent hot accretion flow at ∼0.3 pc (10 ^3 r _g ). There are strong outflows toward the poles driven by the magnetic field. The outflow energy flux increases with smaller accretor size, reaching ∼3 × 10 ^43 erg s ^−1 for r _in = 8 r _g ; this corresponds to a nearly constant energy feedback efficiency of η ∼ 0.05–0.1 independent of accretor size. The feedback energy is enough to balance the total cooling of the M87/Virgo hot halo out to ∼50 kpc. The accreted magnetic flux at small radii is similar to that in magnetically arrested disk models, consistent with the formation of a powerful jet on horizon scales in M87. Our results motivate a subgrid model for accretion in lower-resolution simulations in which the hot gas accretion rate is suppressed relative to the Bondi rate by $\sim {(10\,{r}_{{\rm{g}}}/{r}_{{\rm{B}}})}^{1/2}$ .

Differences between the local value of the Hubble constant measured via the distance ladder versus the value inferred from the cosmic microwave background with the assumption of the standard ΛCDM model have reached over 5 σ significance. To determine if this discrepancy is due to new physics or more mundane systematic errors, it is essential to remove as many sources of systematic uncertainty as possible, by developing high-precision distance ladders that are independent of the traditional Cepheid and Type Ia supernova route. Here, we present JWST observations of three early-type Fornax Cluster galaxies, the first of 14 observations from a Cycle 2 JWST program. Our modest integration times allow us to measure highly precise tip of the red giant branch (TRGB) distances and they will also be used to perform measurements of surface brightness fluctuations (SBFs). From these three galaxies, we determine an average TRGB distance modulus to the Fornax Cluster of μ = 31.424 ± 0.077 mag or D = 19.3 ± 0.7 Mpc. With 11 more scheduled observations in nearby elliptical galaxies, our program will allow us to set the zero-point of the SBF scale to better than 2% for more distant measurements, charting a path toward a high-precision measurement of H _0 that is independent of the traditional Cepheid–supernova Ia distance ladder.

Using “spatially” resolved spectroscopy, we investigated the characteristics and different modes of formation of stars in elliptical galaxies. We identified an unusual population of 59 star-forming elliptical (SF-E) galaxies in SDSS-MaNGA, our primary sample. To identify these rare star-forming ellipticals, we combined GSWLC-A2 containing outputs of stellar population synthesis models with morphological results from the deep-learning catalog and resolved and integrated properties from the MaNGA Pipe3D value-added catalog. We have also constructed two control samples of star-forming spirals (SF-Sps; 2419 galaxies) and quenched ellipticals (Q-Es; 684 galaxies) to compare with our primary sample of SF-Es. H α emission line flux of SF-Es is similar to spiral galaxies. The D4000 spectral index indicates that SF-Es have a mixture of old and young stellar populations. Mass-weighted stellar age and metallicity for the SF-Es are lower than the Q-Es and 67% of stellar- and gas-velocity maps of the primary sample show signs of kinematic disturbance. All of these indicate that SF-Es have acquired metal-poor gas through recent mergers or interactions with other galaxies and are forming a new generation of stars. Further, we subdivide our primary sample of SF-Es into four classes based on their bulge to total luminosity ratio ( B / T ) and spin parameter ${\lambda }_{{re}}$ . These four classes have their distinct evolutionary history and modes of formation. Based on these results, we suggest that the Hubble diagram does not accurately capture galaxy evolution processes, and we need a revised morphology diagram like the comb morphology diagram to get a complete picture of the galaxy evolution processes.

NGC 777 provides an example of a phenomenon observed in some group-central ellipticals, in which the temperature profile shows a central peak, despite the short central cooling time of the intragroup medium. We use deep Chandra X-ray observations of the galaxy, supported by uGMRT 400 MHz radio imaging, to investigate the origin of this hot core. We confirm the centrally peaked temperature profile and find that the entropy and cooling time both monotonically decline to low values (2.62 ${}_{-0.18}^{+0.19}$ keV cm ^2 and ${71.3}_{-13.1}^{+12.8}$ Myr, respectively) in the central ∼700 pc. Faint diffuse radio emission surrounds the nuclear point source, with no clear jets or lobes but extending to ∼10 kpc on the northwest–southeast axis. This alignment and extent agree well with a previously identified filamentary H α + [N ii ] nebula. While cavities are not firmly detected, we see X-ray surface brightness decrements on the same axis at 10–20 kpc radii, which are consistent with the intragroup medium having been pushed aside by expanding radio lobes. Any such outburst must have occurred long enough ago for lobe emission to have faded below detectability. Cavities on this scale would be capable of balancing radiative cooling for at least ∼240 Myr. We consider possible causes of the centrally peaked temperature profile, including gravitational heating of gas as the halo relaxes after a period of active galactic nucleus jet activity, and heating by particles leaking from the remnant relativistic plasma of the old radio jets.

We present a complete census of candidate nuggets, i.e., dense galaxies likely formed by compaction with intense gas influx, within the volume-limited redshift z ∼ 0 REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. These nuggets span all evolutionary stages and 3 orders of magnitude in stellar mass ( M _* ∼ 10 ^8 to 10 ^11 M _⊙ ) from the dwarf to the giant regime. We develop selection criteria for our z ∼ 0 nugget candidates based on structure and introduce the use of environmental criteria to eliminate nugget-like objects with suspected non-compaction origins. The resulting z ∼ 0 nuggets follow expectations with respect to structure (i.e., density, size), population frequency, and likely origins. We show that the properties of our nugget census are consistent with permanent quenching above the gas-richness threshold scale ( halo mass M _halo ∼ 10 ^11.4 M _⊙ ), cyclic temporary quenching below the threshold scale, and feedback from active galactic nuclei (AGN) assisting in permanent quenching. As predicted in simulations, most nuggets quench within a halo mass range of M _halo ∼ 10 ^11.45 to 10 ^11.9 M _⊙ . We find ∼0.29 dex scatter around the star-forming main sequence for candidate blue nuggets below the threshold scale, which is consistent with temporary quenching as seen in simulations. A transitional population of green nuggets appears above the threshold scale. AGN also become more common in nuggets above this scale, and we see a likely AGN excess in nuggets versus comparably selected non-nuggets. Our results provide the first observational confirmation of the mass-dependent, AGN-mediated shift from cyclic quenching to halo quenching in nuggets.

We examine the central stellar velocity dispersion of subhalos based on IllustrisTNG cosmological hydrodynamic simulations. The central velocity dispersion is a fundamental observable that links galaxies with their dark matter subhalos. We carefully explore simulated stellar velocity dispersions derived with different definitions to assess possible systematics. We explore the impact of variation in the identification of member stellar particles, the viewing axes, the velocity dispersion computation technique, and simulation resolution. None of these issues impact the velocity dispersion significantly; any systematic uncertainties are smaller than the random error. We examine the stellar mass–velocity dispersion relation as an observational test of the simulations. At fixed stellar mass, the observed velocity dispersions significantly exceed the simulation results. This discrepancy is an interesting benchmark for the IllustrisTNG simulations because the simulations are not explicitly tuned to match this relation. We demonstrate that the stellar velocity dispersion provides measures of the dark matter velocity dispersion and the dark matter subhalo mass.

Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to a decrease of cold gas. In the first paper we showed that the dust removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide and 21 cm hydrogen line observations of these galaxies and measure the timescale of removal of the cold interstellar medium (ISM). We find that all the cold ISM components (dust and molecular and atomic gas) decline at similar rates. This allows us to rule out a wide range of potential ISM-removal mechanisms (including starburst-driven outflows, astration, or a decline in the number of asymptotic giant branch stars), and artificial effects like the stellar mass–age correlation, environmental influence, mergers, and selection bias, leaving ionization by evolved low-mass stars and ionization/outflows by Type Ia supernovae or active galactic nuclei as viable mechanisms. We also provide evidence for an internal origin of the detected ISMs. Moreover, we find that the quenching of star formation in these galaxies cannot be explained by a reduction in the gas amount alone, because the star formation rates (SFRs) decrease faster (on a timescale of about 1.8 Gyr) than the amount of cold gas. Furthermore, the star formation efficiency (SFE) of the ETGs ( ${\rm{SFE}}\equiv {\rm{SFR}}/{M}_{{{\rm{H}}}_{2}}$ ) is lower than that of star-forming galaxies, whereas their gas mass fractions ( ${f}_{{{\rm{H}}}_{2}}\equiv {M}_{{{\rm{H}}}_{2}}/{M}_{* }$ ) are normal. This may be explained by the stabilization of gas against fragmentation, for example due to morphological quenching, turbulence, or magnetic fields.

The physical quantity that directly controls the feedback of active galactic nuclei (AGNs) in elliptical galaxies remains to be determined. The discovery of molecular gas around the AGNs suggests that the gas is fueling the AGNs. Therefore, we analyze Atacama Large Millimeter/submillimeter Array data for the CO line ( J = 1–0, 2–1, 3–2) emission and estimate the mass of molecular gas within 500 pc of the center of 12 noncentral elliptical galaxies (NCEGs) and 10 of the brightest cluster galaxies. We find that the mass ( M _mol ∼ 10 ^5 –10 ^9 M _☉ ) is correlated with the jet power of their AGNs, which is represented by ${P}_{\mathrm{cav}}\approx 4.1\times {10}^{42}{({M}_{\mathrm{mol}}/{10}^{7}\ {M}_{\odot })}^{1.3}\mathrm{erg}\ {{\rm{s}}}^{-1}$ , although NCEGs alone do not show the correlation. We also find that M _mol is correlated with the AGN continuum luminosities at ∼1.4 GHz ( L _1.4 ) and ∼100–300 GHz ( L _con ). Since P _cav reflects galactic-scale, long-term AGN activity, while the continuum luminosities reflect local (≲500 pc), short-term AGN activity, our results suggest that AGN activity depends on the amount of gas, regardless of its timescale. On the other hand, we cannot find a clear correlation between the mass of the black holes in the AGNs ( M _BH ) and P _cav . This suggests that M _mol , rather than M _BH , is the main factor controlling AGN activity. We confirm that the origin of the continuum emission from the AGNs at ∼1.4–300 GHz is mostly synchrotron radiation.

Parsec-scale massive black hole binaries (MBHBs) are expected to form in hierarchical models of structure formation. Even though different observational strategies have been designed to detect these systems, a theoretical study is a further guide for their search and identification. In this work, we investigate the hosts properties and the electromagnetic signatures of massive black holes gravitationally bound on parsec-scales with primary mass |$\rm {\gt }\, 10^7\, M_{\odot }$|⁠. For that, we construct a full-sky light-cone by the use of the semi-analytical model L-Galaxies   in which physically motivated prescriptions for the formation and evolution of MBHBs have been included. Our predictions show that the large majority of the MBHBs are placed either in spiral galaxies with a classical bulge structure or in elliptical galaxies. Besides, the scaling relations followed by MBHBs are indistinguishable from the ones of single massive black holes. We find that the occupation fraction of parsec-scale MBHBs reaches up to |${\sim }\, 50{{\ \rm per\ cent}}$| in galaxies with |$\rm M_{stellar}\, {\gt }\, 10^{11}\, M_{\odot }$| and drops below 10 per cent for |$\rm M_{stellar}\, {\lt }\, 10^{11}\, M_{\odot }$|⁠. Our model anticipates that the majority of parsec-scale MBHBs are unequal mass systems and lie at |$z\, {\sim }\, 0.5$|⁠ , with |${\sim }\, 20$| objects per |$\rm deg^2$| in the sky. However, most of these systems are inactive, and only |$\rm {1-0.1}$| objects per |$\rm deg^2$| have an electromagnetic counterpart with a bolometric luminosity in excess of 1043 erg s−1. Very luminous phases of parsec-scale MBHBs are more common at |$z\, {\gt }\, 1$|⁠ , but the number of binaries per |$\rm deg^2$| is |${\lesssim }\, 0.01$| at |$\rm L_{\rm bol}\, {\gt }\, 10^{45}\,\rm erg\,s^{-1}$|⁠. [ABSTRACT FROM AUTHOR]

The optical morphology of galaxies is strongly related to galactic environment, with the fraction of early-type galaxies increasing with local galaxy density. In this work, we present the first analysis of the galaxy morphology–density relation in a cosmological hydrodynamical simulation. We use a convolutional neural network, trained on observed galaxies, to perform visual morphological classification of galaxies with stellar masses |$M_\ast \gt 10^{10} \, \rm {M}_{\odot }$| in the EAGLE simulation into elliptical, lenticular and late-type (spiral/irregular) classes. We find that EAGLE reproduces both the galaxy morphology–density and morphology–mass relations. Using the simulations, we find three key processes that result in the observed morphology–density relation: (i) transformation of disc-dominated galaxies from late-type (spiral) to lenticular galaxies through gas stripping in high-density environments, (ii) formation of lenticular galaxies by merger-induced black hole feedback in low-density environments, and (iii) an increasing fraction of high-mass galaxies, which are more often elliptical galaxies, at higher galactic densities. [ABSTRACT FROM AUTHOR]

We study the evolution of L * elliptical galaxies in the colour–magnitude diagram in terms of their star formation history and environment, in an attempt to learn about their quenching process. We have visually extracted 1109 L * galaxies from a sample of 36 500 galaxies that were spectroscopically selected from Stripe82 of the Sloan Digital Sky Survey (SDSS). From this sample, we have selected 51 ellipticals based on their surface-brightness profile being well-fitted by a single S |$\acute{e}$| rsic profile with S |$\acute{e}$| rsic indices 3 < n < 6. Our sample consists of 12 blue-cloud L * ellipticals (BLEs), 11 green-valley L * ellipticals (GLEs), and 28 red-sequence L * ellipticals (RLEs). We find that most of the RLEs and GLEs have been quenched only recently, or are still forming stars, based on their [O  iii ] and H α emission, while the BLEs are forming stars vigorously. The star formation in BLEs is found to be extended over the galaxy and not confined to their central region. In about 40 per cent of the L * ellipticals (10 BLEs, 4 GLEs, and 5 RLEs), star formation quenching seems to have started only recently, based on the lower [O  iii ] emission compared to the [O  ii ] and H α emission, at a given metallicity. We also find that the galaxy colour is correlated with the cosmic-web environment, with the BLEs tending to reside in lower density regions, the RLEs preferring denser, clustered regions, and the GLEs found in either. One possible scenario is that as the star-forming ellipticals migrate into the clusters, their star formation is suffocated by the hot intracluster medium. [ABSTRACT FROM AUTHOR]

While dry mergers can produce considerable scatter in the (black hole mass, M bh)-(spheroid stellar mass, M *, sph) and M bh-(spheroid half-light radius, R e, sph) diagrams, the virial theorem is used here to explain why the scatter about the M bh–(velocity dispersion, σ) relation remains low in the face of such mergers. Its small scatter has been claimed as evidence of feedback from active galactic nuclei (AGNs). However, it is shown that galaxy mergers also play a significant role. The collision of two lenticular (S0) galaxies is expected to yield three types of merger product (a core-Sérsic S0, an ellicular ES,e or an elliptical E galaxy), depending on the remnant's orbital angular momentum. It is shown that the major merger of two S0 galaxies with M *, sph ∼ 1011 M⊙ advances the system along a slope of ∼5 in the M bh-σ diagram, while a major E+E galaxy merger moves a system slightly along a trajectory with a slope of ∼9. Mergers of lower-mass S0 galaxies with M *, sph ∼ 1010 M⊙ move slightly along a trajectory with a slope of ∼3, thereby further contributing to the steeper distribution for the E (and Es,e) galaxies in the M bh-σ diagram, reported here to have a slope of 7.27 ± 0.91, compared to the S0 galaxies that have a slope of 5.68 ± 0.60. This result forms an important complement to the AGN feedback models like that from Silk & Rees, providing a more complete picture of galaxy/(black hole) co-evolution. It also has important implications for nanohertz gravitational-wave research. [ABSTRACT FROM AUTHOR]

Accurate determination of the rates of nova eruptions in different kinds of galaxies gives us strong constraints on those galaxies' underlying white dwarf and binary populations, and those stars' spatial distributions. Until 2016, limitations inherent in ground-based surveys of external galaxies – and dust extinction in the Milky Way – significantly hampered the determination of those rates and how much they differ between different types of galaxies. Infrared Galactic surveys and dense cadence Hubble Space Telescope (HST)-based surveys are overcoming these limitations, leading to sharply increased nova-in-galaxy rates relative to those previously claimed. Here, we present 14 nova candidates that were serendipitously observed during a year-long HST survey of the massive spiral galaxy M51 (the 'Whirlpool Galaxy'). We use simulations based on observed nova light curves to model the incompleteness of the HST survey in unprecedented detail, determining a nova detection efficiency ϵ = 20.3 per cent. The survey's M51 area coverage, combined with ϵ, indicates a conservative M51 nova rate of |$172^{+46}_{-37}$|  novae yr−1, corresponding to a luminosity-specific nova rate (LSNR) of |$\sim\!10.4^{+2.8}_{-2.2}$|  novae yr−1/1010 L ⊙, K . Both these rates are approximately an order of magnitude higher than those estimated by ground-based studies, contradicting claims of universal low nova rates in all types of galaxies determined by low cadence, ground-based surveys. They demonstrate that, contrary to theoretical models, the HST -determined LSNR in a giant elliptical galaxy (M87) and a giant spiral galaxy (M51) likely do not differ by an order of magnitude or more, and may in fact be quite similar. [ABSTRACT FROM AUTHOR]

We study systematics associated with estimating simple stellar population (SSP) parameters – age, metallicity [M/H], α-enhancement [α/Fe], and initial mass function (IMF) shape – and associated M */ L gradients, of elliptical slow rotators (E-SRs), fast rotators (E-FRs), and S0s from stacked spectra of galaxies in the MaNGA survey. These systematics arise from (i) how one normalizes the spectra when stacking; (ii) having to subtract emission before estimating absorption line strengths; (iii) the decision to fit the whole spectrum or just a few absorption lines; (iv) SSP model differences (e.g. isochrones, enrichment, IMF). The MILES+Padova SSP models, fit to the Hβ, 〈Fe〉, TiO2SDSS, and [MgFe] Lick indices in the stacks, indicate that out to the half-light radius Re : (a) ages are younger and [α/Fe] values are lower in the central regions but the opposite is true of [M/H]; (b) the IMF is more bottom-heavy in the center, but is close to Kroupa beyond about Re /2; (c) this makes M */ L about 2 × larger in the central regions than beyond Re /2. While the models of Conroy et al. return similar [M/H] and [α/Fe] profiles, the age and (hence) M */ L profiles can differ significantly even for solar abundances and a Kroupa IMF; different responses to non-solar abundances and IMF parametrization further compound these differences. There are clear (model independent) differences between E-SRs, E-FRs, and S0s: younger ages and less enhanced [α/Fe] values suggest that E-FRs and S0s are not SSPs, but relaxing this assumption is unlikely to change their inferred M */ L gradients significantly. [ABSTRACT FROM AUTHOR]

We present a kinematic study of six dwarf spheroidal galaxies (dSph) satellites of the Milky Way (MW), namely Carina, Draco, Fornax, Sculptor, Sextans, and Ursa Minor. We combine proper motions (PMs) from the Gaia Data Release 3 (DR3) and line-of-sight velocities (v los) from the literature to derive their 3D internal kinematics and to study the presence of internal velocity gradients. We find velocity gradients along the line-of-sight for Carina, Draco, Fornax, and Ursa Minor, at ≥1σ level of significance. The value of such gradients appears to be related to the orbital history of the dwarfs, indicating that the interaction with the MW is causing them. Dwarfs that are close to the MW and moving towards their orbits pericentres show, on average, larger velocity gradients. On the other hand, dwarfs that have recently left their orbits pericentres show no significant gradients. Lastly, dwarfs located at large Galactocentric distances show gradients with an intermediate intensity. Our results would indicate that the torque caused by the strong tidal forces exerted by the MW induces a strong velocity gradient when the dwarfs approach their orbits pericentres. During the pericentre passage, the rapid change in the forces direction would disrupt such gradient, which may steadily recover as the galaxies recede. We assess our findings by analysing dwarfs satellites from the TNG50 simulation. We find a significant increase in the intensity of the detected gradients as the satellites approach their pericentre, followed by a sharp drop as they abandon it, supporting our results for the dSphs of the MW. [ABSTRACT FROM AUTHOR]

Close encounters between two initially unbound objects can result in a binary system if enough energy is released as gravitational waves (GWs). We address the scenario in which such encounters occur in merging elliptical galaxies. There is evidence that elliptical galaxies can harbour intermediate-mass black holes (IMBHs). Therefore, these systems are potentially the breeding grounds of sources of GWs corresponding to inspiraling compact objects onto a massive black hole due to the dynamics, the large densities, and the number of compact remnants they contain. We show that this process is efficient for IMBHs with masses ranging from M ∈ (103, 105) M⊙ and results in the formation of intermediate-mass ratio inspirals (IMRIs). We consider a set of IMBHs and smaller black holes with masses m 2 ∈ (10, 103) M⊙ to estimate the IMRI formation rate. We find rates ranging between 10−8 and 10−5 yr−1, and the IMRI formation rate per comoving volume in merging galaxies as a function of the redshift. The peak frequencies of the gravitational radiation emitted when these IMRIs are formed are within the detection band of space-borne detectors such as the Laser Interferometer Space Antenna (LISA) and TianQin ; taking into account the observable volume of these detectors, the total amount of IMRI detections per year is significant. [ABSTRACT FROM AUTHOR]

We explore the properties of Milky Way (MW) subhaloes in self-interacting dark matter models for moderate cross-sections of 1–5 cm2 g−1 using high-resolution zoom-in N -body simulations. We include the gravitational potential of a baryonic disc and bulge matched to the MW, which is critical for getting accurate predictions. The predicted number and distribution of subhaloes within the host halo are similar for 1 and 5 cm2 g−1 models, and they agree with observations of MW satellite galaxies only if subhaloes with peak circular velocity over all time >7 km s−1 are able to form galaxies. We do not find distinctive signatures in the pericentre distribution of the subhaloes that could help distinguish the models. Using an analytical model to extend the simulation results, we are able to show that subhaloes in models with cross-sections between 1 and 5 cm2 g−1 are not dense enough to match the densest ultrafaint and classical dwarf spheroidal galaxies in the MW. This motivates exploring velocity-dependent cross-sections with values larger than 5 cm2 g−1 at the velocities relevant for the satellites such that core collapse would occur in some of the ultrafaint and classical dwarf spheroidals. [ABSTRACT FROM AUTHOR]

We present revised (black hole mass)–(spheroid stellar mass) and (black hole mass)–(galaxy stellar mass) scaling relations based on colour-dependent (stellar mass)-to-light ratios. Our 3.6  |$\mu$| m luminosities were obtained from multicomponent decompositions, which accounted for bulges, discs, bars, ansae, rings, nuclear components, etc. The lenticular galaxy bulges (not associated with recent mergers) follow a steep |$M_{\rm {bh}}\propto ~M_{\rm {*,bulge}}^{1.53\pm 0.15}$| relation, offset by roughly an order of magnitude in black hole mass from the |$M_{\rm {bh}}\propto ~M_{\rm {*,ellip}}^{1.64\pm 0.17}$| relation defined by the elliptical (E) galaxies which, in Darwinian terms, are shown to have evolved by punctuated equilibrium rather than gradualism. We use the spheroid (i.e. bulge and elliptical) size–mass relation to reveal how disc-galaxy mergers explain this offset and the dramatically lower M bh/ M *,sph ratios in the elliptical galaxies. The deceptive near-linear M bh– M *,sph 'red sequence', followed by neither the bulge population nor the elliptical galaxies, is shown to be an artefact of sample selection, combining bulges and elliptical galaxies from disparate M bh– M *,sph sequences. Moreover, both small bulges with 'undermassive' black holes and big lenticular galaxies (including relic 'red nuggets') with 'overmassive' black holes – relative to the near-linear M bh– M *,sph sequence – are no longer viewed as outliers. We confirm a steep |$M_{\rm {bh}}\propto ~M_{\rm {*,bulge}}^{2.25\pm 0.39}$| relation for spiral galaxies and discuss numerous implications of this work, including how mergers, rather than (only) feedback from active galactic nuclei, have shaped the high-mass end of the galaxy mass function. We also explain why there may be no useful M bh– M *,sph– R e,sph plane due to M *,sph scaling nearly linearly with R e,sph. [ABSTRACT FROM AUTHOR]

We investigate the velocity distribution of elliptical galaxies in the framework of Non-local Gravity. According to this approach, it is possible to recover the fundamental plane of elliptical galaxies without the dark matter hypothesis. Specifically, we compare theoretical predictions for circular velocity in Non-local Gravity context with the corresponding values coming from a large sample of observed elliptical galaxies. We adopt the surface brightness, effective radius and velocity dispersion as structural parameters for the fundamental plane. As final result, it is possible to show that non-local gravity effects can reproduce the stellar dynamics in elliptical galaxies and fit consistently observational data. [ABSTRACT FROM AUTHOR]

Alternative cosmological models have been under deep scrutiny in recent years, aiming to address the main shortcomings of the Λ CDM model. Moreover, as the accuracy of cosmological surveys improved, new tensions have risen between the model-dependent analysis of the Cosmic Microwave Background and lower redshift probes. Within this framework, we review two quantum-inspired non-locally extended theories of gravity, whose main cosmological feature is a geometrically driven accelerated expansion. The models are especially investigated in light of the Hubble and growth tension, and promising features emerge for the Deser–Woodard one. On the one hand, the cosmological analysis of the phenomenological formulation of the model shows a lowered growth of structures but an equivalent background with respect to Λ CDM. On the other hand, the study of the lensing features at the galaxy cluster scale of a new formulation of non-local cosmology, based on Noether symmetries, makes room for the possibility of alleviating both the H 0 and σ 8 tension. However, the urgent need for a screening mechanism arises for this non-local theory of gravity. [ABSTRACT FROM AUTHOR]

We study the formation and evolution of elliptical galaxies and how they suppress star formation and maintain it quenched. A one-zone chemical model which follows in detail the time evolution of gas mass and its chemical abundances during the active and passive evolution is adopted. The model includes both gas infall and outflow as well as detailed stellar nucleosynthesis. Elliptical galaxies with different infall masses, following a down-sizing in star formation scenario, are considered. In the chemical evolution simulation, we include a novel calculation of the feedback processes. We include heating by stellar wind, core-collapse supernovae (SNe), Type Ia SNe (usually not highlighted in galaxy formation simulations), and active galactic nucleus (AGN) feedback. The AGN feedback is a novelty in this kind of models and is computed by considering a Bondi-Eddington limited accretion onto the central supermassive black hole. We successfully reproduce several observational features, such as the [α/Fe] ratios increasing with galaxy mass, mass-metallicity, M BH–σ and M BH– M * relations. Moreover, we show that stellar feedback and in particular Type Ia SNe, has a main role in maintaining quenched the star formation after the occurrence of the main galactic wind, especially in low-mass ellipticals. For larger systems, the contribution from AGN to thermal energy of gas appears to be necessary. However, the effect of the AGN on the development of the main galactic wind is negligible, unless an unreasonable high-AGN efficiency or an extremely low-stellar feedback are assumed. We emphasize the important role played by Type Ia SNe in the energy budget of early-type galaxies. [ABSTRACT FROM AUTHOR]

The content and distribution of cool interstellar medium (<30 K) can indicate the evolutionary mechanisms that transform late-type to early-type galaxies (ETGs). To investigate this, ALMA observations of 12CO[2-1] line emission were obtained for five dusty ETGs from a complete sample in low-density environments. Four of the ETGs have massive (∼109 M⊙), extended molecular gas reservoirs with effective radii ∼3–5 kpc. This work provides a kinematic and structural analysis of these observations, to explore possible evolutionary mechanisms. Axisymmetric or bisymmetric kinematic models were fitted to observations of molecular gas discs, to quantify the dominant structures present and highlight additional structures or asymmetries. Integral field unit observations of these ETGs were also examined where available. Two of the ETGs, GAMA64646 and 622305, appear to have undergone tidal disturbance leading to molecular gas discs and/or star-forming inner rings. GAMA272990 may have undergone a merger, leading to an elliptical galaxy with an embedded star-forming molecular gas disc. GAMA622429 has probably undergone a minor merger, indicated by asymmetry in molecular gas distribution and disturbance in optical images. The remaining ETG, GAMA177186, was affected by source confusion from an offset source which could be a high-mass dust- and gas-rich object at high redshift. Overall, it appears that a high proportion of dusty ETGs in low-density environments have massive, extended molecular gas reservoirs, and have undergone some kind of interaction as part of their recent evolution. Secular evolution can then (re-)transform the ETGs from star-forming to passive galaxies. [ABSTRACT FROM AUTHOR]

We present a comprehensive metallicity analysis of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) using Pristine CaHK photometry. We base our member selection on Gaia EDR3 astrometry, applying a magnitude limit at G 0 = 17.3, and our population study on the metallicity-sensitive photometry from the Pristine Inner Galaxy Survey (PIGS). Working with photometric metallicities instead of spectroscopic metallicities allows us to cover an unprecedented large area (∼100 square degrees) of the dwarf galaxy, and to study the spatial distribution of its members as function of metallicity with little selection effects. Our study compares the spatial distributions of a metal-poor population of 9719 stars with [Fe/H] <−1.3 and a metal-rich one of 30 115 stars with [Fe/H] >−1.0. The photometric Sgr sample also allows us to assemble the largest sample of 1150 very metal-poor Sgr candidates ([Fe/H] <−2.0). By investigating and fitting the spatial properties of the metal-rich and metal-poor population, we find a negative metallicity gradient which extends up to 12 degrees from the Sgr centre (or ∼5.5 kpc at the distance of Sgr), the limit of our footprint. We conclude that the relative number of metal-poor stars increases in the outer areas of the galaxy, while the central region is dominated by metal-rich stars. These findings suggest an outside-in formation process and are an indication of the extended formation history of Sgr, which has been affected by the tidal interaction between Sgr and the Milky Way. [ABSTRACT FROM AUTHOR]

The gravitational lensing signal produced by a galaxy or a galaxy cluster is determined by its total matter distribution, providing us with a way to directly constrain their dark matter content. State-of-the-art numerical simulations successfully reproduce many observed properties of galaxies and can be used as a source of mock observations and predictions. Many gravitational lensing studies aim at constraining the nature of dark matter, discriminating between cold dark matter and alternative models. However, many past results are based on the comparison to simulations that did not include baryonic physics. Here we show that the presence of baryons can significantly alter the predictions: we look at the structural properties (profiles and shapes) of elliptical galaxies and at the inner density slope of subhaloes. Our results demonstrate that future simulations must model the interplay between baryons and alternative dark matter, to generate realistic predictions that could significantly modify the current constraints. [ABSTRACT FROM AUTHOR]

While the direct detection of the dark-matter particle remains very challenging, the physical properties of dark matter could potentially be constrained indirectly – by comparing the population characteristics of substructures in real galaxies with predictions from the phenomenological dark-matter models, such as cold, warm or self-interacting dark matter. Whereas these models are practically indistinguishable with respect to the expected abundance and statistical properties of massive galactic substructures, the critical difference lies in the low-mass regime ≲ 108 M ⊙. Galaxy-galaxy strong gravitational lensing provides a unique opportunity to search for gravitational signatures of such low-mass substructures in galaxies acting as a strong gravitational lens on a more distant background galaxy, serendipitously located along the same line of sight. In [Bayer et∼al.(2023)Bayer, Chatterjee, Koopmans, Vegetti, McKean, Treu, Fassnacht, and Glazebrook, Bayer et∼al.(2023)Bayer, Koopmans, McKean, Vegetti, Treu, Fassnacht, and Glazebrook, Bayer et∼al.(2023)Bayer, Vernardos, and Koopmans], we have recently introduced a novel approach to investigate the collective perturbative effect of low-mass substructures in the inner regions of massive elliptical lens galaxies and observationally constrain their power spectrum (on 1-10 kpc scales) based on the Fourier analysis of the associated surface-brightness anomalies in the lensed images (i.e., Einstein rings and gravitational arcs) observed with the Hubble Space Telescope. Here, we present a concise summary of the methodology, the encountered modelling challenges and the inferred observational constraints on the sub-galactic matter power spectrum. The future comparison of these results with predictions from hydrodynamical simulations might either verify the cold-dark-matter paradigm or require its substantial revision. Moreover, we demonstrate that the grid-based smooth lens modelling might model away surface-brightness anomalies caused by the presence of substructures in the lens galaxy and incorrectly interpret them as surface-brightness structure in the lensed background galaxy itself. If not properly understood and accounted for, such signal suppression might lead to severely biased constraints on the properties of substructures in galactic haloes. [ABSTRACT FROM AUTHOR]

From various lensing and non-lensing observations, the total density profile in elliptical galaxies is well approximated by a power law mass distribution. However, as neither the dark matter nor the baryons individually follow the power law, this observational result has been referred to as the "bulge–halo conspiracy". We investigate the consistency of this conspiracy with higher precision than previous studies with the largest ever sample of galaxy–galaxy lenses assembled from archival Hubble Space Telescope (HST) data. By performing lens modelling with power law profiles and combining them with stellar dynamics using the mass-sheet transformation, we can constrain the profile's deviation from the power law model over a redshift range of 0.1 to 0.8. To uniformly model such a large sample of lens models, we use the automated modelling pipeline dolphin. We also investigate the evolutionary trend of the total mass density slope of the lensing galaxies. [ABSTRACT FROM AUTHOR]

Rare systems with multiple sources strongly lensed by a single galaxy provide the most robust way to explore the geometry of the Universe and to study the inner mass structure of lens galaxies. We present here a study of the SDSS J0100+1818 deflector, analyzing its total and baryonic mass distributions. The system comprises an ultra-massive early-type galaxy, surrounded by ten multiple images of three background sources. Exploiting high-resolution HST photometry and VLT/X-shooter spectroscopy we conduct a strong lensing analysis with the software GLEE to reconstruct the complex surface brightness distributions of the background sources over approximately 7200 HST pixels. These results are presented in our recent paper, Bolamperti et al. (2023). Finally, we present some preliminary results from new VLT/MUSE observations, that will allow us to build a new strong lensing+dynamics joint model and measure the values of the total matter density and of the cosmological constant parameters, Ω m and ΩΛ. [ABSTRACT FROM AUTHOR]

Thanks to forthcoming large-scale surveys, a tremendous number of strong lenses will be discovered in the coming years. The gain in accuracy on H 0 from such a large population of lensed quasars is a key question for the future of time-delay cosmography. In such context, lensed systems will have to be modeled in an automated way, with models that are sufficiently generic to apply to every lens. I explore the biases that may arise from unaccounted-for azimuthal structures in mass models. The non-modeled twists in lensing galaxies are expected to bias the shear inference but not H 0. Disregarded ellipticity gradients, boxyness and discyness may impact the cosmological inference on a lens-by-lens basis. Nevertheless, the diversity of azimuthal mass profile in lenses balances the bias at a population level and the H 0 inference can thus benefits from such large surveys. [ABSTRACT FROM AUTHOR]

The existence of non-baryonic cold dark matter has been established by several astrophysical evidences. In the regions of high dark matter density, the dark matter particles can undergo self-annihilation yielding standard model particles. Such particles may have effects on the observational properties of astronomical objects, which may then be used to constrain the nature of dark matter. High-energy electrons and positrons produced by dark matter annihilation in an astrophysical system emit synchrotron radiation due to the presence of the magnetic field. This synchrotron radiation can be detected by a radio telescope. Dwarf spheroidal galaxies of the Milky Way are some of the darkest matter-dominated objects in the Universe and thus provide natural targets for indirect dark matter searches or to constrain the synchrotron signal from the annihilation of dark matter. In this work, we study the radio emission due to neutralino dark matter emission in the nearby dwarf spheroidal galaxies – Ursa Minor, Willman I, Sculptor and Ursa Major II. Assuming the Navarro–Frenk–White (NFW) dark matter density profile within the halo of the dwarf galaxies, the upper limit of synchrotron flux is found to be ~10−14 ergs cm−2 s−1 for neutralino mass M χ = 1 TeV annihilating into μ+μ− state and B0 = 4 μG. For B0 = 2 μG, the flux is one order less. It is seen that as the electron energy approaches the neutralino mass, electron number density decreases. Moreover, the peak frequency is found to follow a power-law with the neutralino mass with a universal exponent. [ABSTRACT FROM AUTHOR]

Satisfactory description of gravitational and gravity potential is needed for a proper modelling of a wide spectrum of physical problems on various size scales, ranging from atmosphere dynamics up to the movement of stars in a galaxy. The presented orthogonal similar oblate spheroidal (SOS) coordinate system can be a modelling tool applicable for a broad variety of objects exhibiting density, gravity or gravitation potential levels resembling similar oblate spheroids. This can be the case inside or in the vicinity of various oblate spheroidal objects (planets, stars, elliptical galaxies, disk galaxies) exhibiting broad range of oblateness. Although the solution of the relevant expressions for the SOS system cannot be written in a closed form, they are derived as analytical expressions—convergent infinite power series employing generalized binomial coefficients. Transformations of SOS coordinates to and from the Cartesian coordinates are shown. The corresponding partial derivatives are found in a suitable form, further enabling derivation of the metric scale factors necessary for differential operations. The terms containing derivatives of the metric scale factors in the velocity advection term of the momentum equation in the SOS coordinate system are expressed. The Jacobian determinant is derived as well. [ABSTRACT FROM AUTHOR]

We investigate how the X-ray circumgalactic medium (CGM) of present-day galaxies depends on galaxy morphology and azimuthal angle using mock observations generated from the EAGLE cosmological hydrodynamic simulation. By creating mock stacks of eROSITA -observed galaxies oriented to be edge-on, we make several observationally testable predictions for galaxies in the stellar mass range M ⋆ = 1010.7–11.2 M⊙. The soft X-ray CGM of disc galaxies is between 60 and 100 per cent brighter along the semimajor axis compared to the semiminor axis, between 10 and 30 kpc. This azimuthal dependence is a consequence of the hot (T > 106 K) CGM being non-spherical: specifically, it is flattened along the minor axis such that denser and more luminous gas resides in the disc plane and corotates with the galaxy. Outflows enrich and heat the CGM preferentially perpendicular to the disc, but we do not find an observationally detectable signature along the semiminor axis. Spheroidal galaxies have hotter CGMs than disc galaxies related to spheroids residing at higher halo masses, which may be measurable through hardness ratios spanning the 0.2–1.5 keV band. While spheroids appear to have brighter CGMs than discs for the selected fixed M ⋆ bin, this owes to spheroids having higher stellar and halo masses within that M ⋆ bin, and obscures the fact that both simulated populations have similar total CGM luminosities at the exact same M ⋆. Discs have brighter emission inside 20 kpc and more steeply declining profiles with radius than spheroids. We predict that the eROSITA 4-yr all-sky survey should detect many of the signatures we predict here, although targeted follow-up observations of highly inclined nearby discs after the survey may be necessary to observe some of our azimuthally dependant predictions. [ABSTRACT FROM AUTHOR]

In Ref. [10] , we proposed to replace the final dark matter (DM) particle in the semi-annihilation mode DM + DM → antiDM + Higgs boson with its Z N ≥ 3 companion, thus reducing DM number density without DM-nucleon scattering. In this work, we study the indirect detection signals from DM annihilation, the Higgs boson pair with one of them from the companion decay being on- or off- shell, depending on the DM-companion mass splitting. We generate the photon spectrum by using PYTHIA8 and study the properties of the spectrum, to find that the hard part of the spectrum in our model is mainly shaped by the direct Higgs boson and thus does not differ much from that of the conventional semi-annihilation mode. Using the Fermi-LAT data of dwarf spheroidal galaxies, we derive the current limit of the DM annihilation cross section for DM + DM → companio n ⁎ + Higgs boson , and for the relatively light DM, it reaches the typical thermal cross section. However, for the TeV scale DM, we have to rely on the Cherenkov Telescope Array, which is able to rule out the whole parameter space except for the coannihilation region. [ABSTRACT FROM AUTHOR]

Minor mergers are thought to drive the structural evolution of massive quiescent galaxies; however, existing Hubble Space Telescope (HST) imaging is primarily sensitive to stellar mass ratios ≳1:10. Here, we report the discovery of a large population of low-mass companions within 35 kpc of known $\mathrm{log}{M}_{* }/{M}_{\odot }\gtrsim 10.5$ quiescent galaxies at 0.5 ≤ z ≤ 3. While massive companions like those identified by HST are rare, JWST imaging from the JWST Advanced Deep Extragalactic Survey reveals that the average massive quiescent galaxy hosts approximately five nearby companions with stellar mass ratios

All stellar evolution models require an initial isotopic abundance set as input, but these abundances are well known only for the Sun. Yet, input compositions can be estimated by scaling solar abundances using a previously constructed isotopic history model based on astrophysical processes in the Galaxy. This method, however, may not work for obtaining inputs for compositions that have distinct chemical histories from the Galaxy. We thus present a partial isotopic history model for the Sculptor dwarf spheroidal galaxy based on astrophysical processes, which can be used to estimate input isotopic abundances in future nucleosynthesis studies. The model is fitted to observational data, and follows the methodology of the previously constructed isotopic history model for the Galaxy. First, we estimate the isotopic composition of Sculptor's late-stage evolution (LSE) using the omega chemical evolution code, and then decompose that composition into contributions from various astrophysical sources. Each contribution is then assumed to scale as a function of metallicity. The isotopic abundances are summed into elemental abundances and fit to available observational elemental abundance data to tune the model's free parameters. The result is an average isotopic history model of Sculptor for massive star, Type Ia SNe, s -process, and r -process contributions that uses elemental data to constrain the isotopic abundances. As an example, our model finds that Type Ia SNe contribute ≈ 87 percent to the LSE Fe abundance, and neutron star mergers contribute ≈ 36 percent to the LSE Eu abundance, in agreement with previous studies. [ABSTRACT FROM AUTHOR]