Preparing for low surface brightness science with the Vera C. Rubin Observatory: Characterization of tidal features from mock images

Abstract

Tidal features in the outskirts of galaxies yield unique information about their past interactions and are a key prediction of the hierarchical structure formation paradigm. The Vera C. Rubin Observatory is poised to deliver deep observations for potentially of millions of objects with visible tidal features, but the inference of galaxy interaction histories from such features is not straightforward. Utilising automated techniques and human visual classification in conjunction with realistic mock images produced using the NewHorizon cosmological simulation, we investigate the nature, frequency and visibility of tidal features and debris across a range of environments and stellar masses. In our simulated sample, around 80 per cent of the flux in the tidal features around Milky Way or greater mass galaxies is detected at the 10-year depth of the Legacy Survey of Space and Time (30 − 31 mag arcsec−2), falling to 60 per cent assuming a shallower final depth of 29.5 mag arcsec−2. The fraction of total flux found in tidal features increases towards higher masses, rising to 10 per cent for the most massive objects in our sample (M⋆ ∼ 1011.5 M⊙). When observed at sufficient depth, such objects frequently exhibit many distinct tidal features with complex shapes. The interpretation and characterisation of such features varies significantly with image depth and object orientation, introducing significant biases in their classification. Assuming the data reduction pipeline is properly optimised, we expect the Rubin Observatory to be capable of recovering much of the flux found in the outskirts of Milky Way mass galaxies, even at intermediate redshifts (z < 0.2).

A New Era of Intracluster Light Studies with JWST

“…The plumes seen in the center of the cluster from ∼25 to 100 kpc (Figure 1) indicate that the BCG of this cluster is likely experiencing a merger (see also Duc et al 2015;Martin et al 2022). At the same time, the measured color is flat in the inner ∼100 kpc in both the east and west profiles, indicating that the stellar populations in this region are well mixed.…”

Massive Early-type Galaxies in the HSC-SSP: Flux Fraction of Tidal Features and Merger Rates

“…In our work, we focus on the flux fraction of tidal features ( f tidal ) and its distribution and try to establish the connection between flux fraction, visible time of tidal features, and merger rates of their hosts. Simulations have found that the detection rate of tidal features is dependent on the surface brightness limit and the projection angle (e.g., Ji et al 2014;Mancillas et al 2019;Martin et al 2022), so what we measured is certainly only the tip of the iceberg of fainter and more extended structures. However, these factors are hard to account for with observational data alone.…”

“…In our work, another factor contributing to this discrepancy is the mask we use in Section 3.2.3 to exclude clustered noise from the detection. Also, a significant fraction of tidal features are expected to extend to a galactocentric radius beyond 25 R eff for the most massive galaxies (Martin et al 2022), which is much larger than our choice (∼15 R eff ) in Section 3.3. The fact that we cannot detect tidal features at large galactocentric radii is also caused by the surface brightness limit, since tidal features gradually dissipate and become fainter as they move outward.…”

“…Based on previous studies, both the merger rates and the ex situ mass fraction of ETGs have been found to increase with stellar mass, which implies that tidal features are likely to appear more frequently in more massive ETGs. In both observations and simulations, visual inspections have shown that the fraction of ETGs showing tidal features indeed increases with stellar mass (e.g., Bílek et al 2020;Yoon & Lim 2020;Martin et al 2022). For example, Yoon & Lim (2020) found that only 2%-5% of ETGs with dynamical mass M dyn < 10 10.4 M e show tidal features in coadded images of SDSS Stripe 82, while this fraction increases to about 30%-40% for massive ETGs with M dyn > 10 11.4 M e .…”

“…The observability of tidal features depends strongly on the surface brightness limit (e.g., Ji et al 2014;Mancillas et al 2019). And numerical simulations have shown that the majority of the tidal features are visible only when the limiting surface brightness goes down to 30 mag arcsec −2 in the r band (e.g., Johnston et al 2008;Martin et al 2022). In Figure 9, we present the distribution of the average surface brightness of all the connected areas detected by the algorithm, showing a detection limit of m » 27 r i , lim mag arcsec −2 .…”