Galaxy formation and evolution

Abstract:

Abstract Disc winds play a crucial role in many accreting astrophysical systems across all scales. In accreting white dwarfs (AWDs) and active galactic nuclei (AGN), radiation pressure on spectral lines is a promising wind-driving mechanism. However, the efficiency of line driving is extremely sensitive to the ionization state of the flow, making it difficult to construct a reliable physical picture of these winds. Recently, we presented the first radiation-hydrodynamic (RHD) simulations for AWDs that incorporated detailed, multi-dimensional ionization calculations via fully frequency-dependent radiative transfer, using the Sirocco code coupled to Pluto. These simulations produced much weaker line-driven winds ($\dot{M}_{\rm wind}/\dot{M}_{\rm acc} < 10^{-5}$ for our adopted parameters) than earlier studies using more approximate treatments of ionization and radiative transfer (which yielded $\dot{M}_{\rm wind}/\dot{M}_{\rm acc} \simeq 10^{-4}$). One remaining limitation of our work was the assumption of an isothermal outflow. Here, we relax this by adopting an ideal gas equation of state and explicitly solving for the multi-dimensional temperature structure of the flow. In the AWD setting, accounting for the thermal state of the wind does not change the overall conclusions drawn from the isothermal approximation. Our new simulations confirm the line-driving efficiency problem: the predicted outflows are too highly ionized, meaning they neither create optimal driving conditions, nor reproduce the observed ultraviolet wind signatures. Possible solutions include wind clumping on sub-grid scales, a softer-than-expected spectral energy distribution or additional driving mechanisms. With the physics now built into our simulations, we are well-equipped to also explore line-driven disc winds in AGN.

Abstract:

Abstract Black hole X-ray binaries in outburst launch discrete, large-scale jet ejections which can propagate to parsec scales. The kinematics of these ejecta appear to be well described by relativistic blast wave models original devised for gamma-ray burst afterglows. In previous kinematic-only modelling, a crucial degeneracy prevented the initial ejecta energy and the interstellar medium density from being accurately determined. In this work, we present the first joint Bayesian modelling of the radiation and kinematics of a large-scale jet ejection from the X-ray binary MAXI J1535-571. We demonstrate that a reverse shock powers the bright, early ejecta emission. The joint model breaks the energetic degeneracy, and we find the ejecta has an initial energy of E0 ∼ 3 × 1043 erg, and propagates into a low density interstellar medium of nism ∼ 4 × 10−5 cm−3. The ejecta is consistent with being launched perpendicular to the disc and could be powered by an efficient conversion of available accretion power alone. This work lays the foundation for future parameter estimation studies using all available data of X-ray binary jet ejecta.

Abstract:

Abstract The radial acceleration relation (RAR) is a fundamental relation linking baryonic and dark matter in galaxies by relating the observed acceleration derived from dynamics to the one estimated from the baryonic mass. This relation exhibits small scatter, thus providing key constraints for models of galaxy formation and evolution—allowing us to map the distribution of dark matter in galaxies—as well as models of modified dynamics. However, it has only been extensively studied in the very local Universe with largely heterogeneous samples. We present a new measurement of the RAR, utilising a homogeneous sample of 19 H i-selected galaxies out to z = 0.08. We introduce a novel approach of measuring resolved stellar masses using spectral energy distribution (SED) fitting across 10 photometric bands to determine the resolved mass-to-light ratio, which we show is essential for measuring the acceleration due to baryons in the low-acceleration regime. Our results reveal a tight RAR with a low-acceleration power-law slope of ∼0.5, consistent with previous studies. Adopting a spatially varying mass-to-light ratio yields the tightest RAR with an intrinsic scatter of only 0.045 ± 0.022 dex, highlighting the importance of resolved stellar mass measurements in accurately characterising the gravitational contribution of the baryons in low-mass, gas-rich galaxies. We also find the first tentative evidence for redshift evolution in the acceleration scale, but more data will be required to confirm this. Adopting a more general MOND interpolating function, we find that our results ameliorate the tension between previous RAR analyses, the Solar System quadrupole and wide-binary test.

Abstract:

We present JWST/NIRSpec integral field spectroscopic (IFS) observations of the Lyα emitter CR7 at z ∼ 6.6, observed as part of the GA-NIFS program. Using low-resolution PRISM (R ∼ 100) data, we confirm the observation of a bright Lyα emitter with a diffuse Lyα halo extending up to 3 kpc from the peak of ionised emission. Both features are associated with 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 performed a spectral energy distribution fitting of the low-resolution data, and it 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 and favouring the merger scenario for CR7. From the high-resolution G395H (R ∼ 2700) data, we discovered at least one additional companion mainly traced by the [O  III ]λ5007 emission line, although it is not detected in continuum emission. We disentangled the kinematics of the system and reveal extended ionised emission linking the main galaxy and the satellite. We spatially resolved the [O  III ]λ5007, [O  III ]4363, and Hγ emission lines and used a diagnostic diagram tailored to high-z systems to reveal tentative evidence of active galactic nucleus ionisation across the main galaxy (CR7-A) and the N-E companion (CR7-B). Moreover, we detected an unresolved blueshifted outflow from one of the satellites and present first evidence for a redshifted outflow from the main galaxy. Finally, we computed the resolved electron temperature (T e ∼1.6×10 4 K) and metallicity maps (log(Z/Z ⊙ ) from –0.8 to –0.5), and we provide insights on how the physical properties of the system evolved at earlier epochs.

Abstract:

Active galactic nuclei (AGNi) are a key ingredient in galaxy evolution and possibly shape galaxy growth through the generation of powerful outflows. Little is known regarding AGN-driven ionized outflows in moderate-luminosity AGNi (log( L bol /erg s −1 )<47) beyond cosmic noon ( z ≳3). In this work we present the first systematic analysis of the ionized outflow properties of a sample of seven X-ray-selected AGNi (log( L X /erg s −1 )>44) from the COSMOS-Legacy field at z ≃3.5 and with log( L bol /erg s −1 ) = 45.2−46.7 by using JWST NIRSpec/IFU near-IR spectroscopic observations as part of the “Galaxy Assembly with NIRSpec IFS” (GA-NIFS) program. We spectrally isolated and spatially resolved the ionized outflows by performing a multi-component kinematic decomposition of the rest-frame optical emission lines. JWST/NIRSpecIFU data also revealed a wealth of close-by companions, of both non-AGN and AGN nature, and ionized gas streams likely tracing tidal structures and large-scale ionized gas nebulae extending up to the circumgalactic medium. Ionized outflows were detected in all COS-AGNi targets, with outflow masses in the range 1.5−11×10 6 M ⊙ , outflow velocities in the range ≃570−3200 km s −1 , and mass outflow rates in the range ≃1.4−40 M ⊙ yr −1 . We compared the outflow properties of AGNi presented in this work with previous results from the literature up to z ≃3, which were opportunely (re-)computed for a coherent comparison. We normalized outflow energetics ( Ṁ out , Ė out ) to the outflow density in order to standardize the various assumptions that were made in the literature. Our choice is equal to assuming that each outflow has the same gas density. We find GA-NIFS AGNi to show outflows consistent with literature results, within the large scatter shown by the collected measurements, thus suggesting no strong evolution with redshift in terms of total mass outflow rate, energy budget, and outflow velocity for fixed bolometric luminosity. Moreover, we find no clear redshift evolution of the ratio of mass outflow rate and kinetic power over AGNi bolometric luminosity beyond z >1. In general, our results indicate no significant evolution of the physics driving outflows beyond z ≃3.