Galaxy formation and evolution

Abstract:

Stellar bars are elongated structures in disk galaxies that can torque and funnel gas inward, influencing galaxy evolution. While strong bars are known to induce rapid inflow, the impact of weaker bars remains less certain. We collected spectroscopic data using the Isaac Newton Telescope to analyze 18 nearby galaxies (strongly barred, weakly barred, and unbarred) drawn from Galaxy Zoo DESI. We obtained spatial profiles of equivalent width (EW) and ionized gas velocity dispersion by fitting Gaussian profiles to the Hα emission line. Strongly barred galaxies exhibit a distinctive three-peaked EW[Hα] structure, consistent with inward funneling of gas. Weakly barred systems lack this pattern, which suggests limited inflow. Velocity dispersion distributions further distinguish the bar types, with strongly barred galaxies showing significantly higher values than weakly barred and unbarred systems. These results suggest that strong bars drive gas inflow, while weak bars exert a limited dynamical influence.

Abstract:

Time-delay cosmography leverages strongly lensed quasars to measure the Universe's current expansion rate, _ independently from other methods. The latest TDCOSMO milestone measurement primarily used quadruply lensed quasars for their mass profile constraints. However, doubly lensed quasars, being more abundant and offering precise time delays, could expand the sample by a factor of 5, significantly advancing towards a 1% precision measurement of We present the first TDCOSMO analysis of a doubly imaged source, ̋Eonze, including the measurement of the four necessary ingredients. First, by combining 17 years of data from the SMARTS, Euler, and WFI telescopes, we measured a time delay of 176.3 +11.4 -10.3 days. Second, using MUSE data, we extracted stellar velocity dispersion measurements in three radial bins with 5% to 13% precision. Third, employing F160W HST imaging for lens modelling and marginalising over various modelling choices, we measured the Fermat potential difference between the images. Fourth, using wide-field imaging, we measured the convergence added by objects not included in the lens modelling. By combining these four ingredients, we measured the time delay distance and the angular diameter distance to the deflector, favouring a power-law mass model over a baryonic and dark matter composite model. The measurement was performed blindly to prevent experimenter bias and resulted in a Hubble constant of hc = 64.2^ +5.8 _ -5.0 times łint ̨msmpc, where łint is the internal mass sheet degeneracy parameter. This is in agreement with the TDCOSMO-2025 milestone and its precision for łint=1 is comparable to that obtained with the best-observed quadruply lensed quasars (4-6%). This work is a stepping stone towards a precise measurement of using a large sample of doubly lensed quasars, supplementing the current sample. The next TDCOSMO milestone paper will include this system in its hierarchical analysis, constraining łint and jointly with multiple lenses.

Abstract:

We present observational evidence that intense ionizing radiation from a luminous quasar suppresses nebular emission in nearby galaxies on intergalactic scales at z = 6.3. Using JWST/NIRCam grism spectroscopy from the Slitless Areal Pure-Parallel High-Redshift Emission survey and Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization programs, we identify a moderate but statistically significant decline in [O iii] λ5008 luminosity relative to the UV continuum (L5008/L1500) among galaxies within ∼7 comoving Mpc (cMpc) of the quasar J0100+2802, the most UV-luminous quasar known at this epoch (M1450 = −29.26). While L1500 remains roughly constant with transverse distance, L5008 increases significantly, suggesting suppression of very recent star formation toward the quasar. The effect persists after controlling for completeness, local density, and UV luminosity, and correlates with the projected photoionization-rate profile Γqso. A weaker but directionally consistent suppression in L5008/L1500 is also observed along the line of sight. The transverse suppression radius (∼7 cMpc) implies a recent radiative episode with a cumulative duration ∼3.1 Myr, shorter than required for thermal photoheating to dominate and thus more naturally explained by rapid H2 photodissociation and related radiative processes. Environmental effects alone appear insufficient to explain the signal. Our results provide direct, geometry-based constraints on large-scale quasar radiative feedback and recent quasar lifetimes.