[Paper Review] Tidal Streams around External Galaxies

M. Pohlen, David Martínez‐Delgado+4 more|arXiv (Cornell University)|Aug 8, 2003

Impact of Light on Environment and Health3 citations

TL;DR

This paper presents four new candidate tidal streams around external disk galaxies, detected via deep wide-field imaging surveys, and reports the first modern CCD measurement of the surface brightness of M83's stellar stream. The study advances the search for low-surface-brightness tidal features to test hierarchical galaxy formation models, offering new observational constraints on minuscule merger rates and progenitor masses in spiral galaxies.

ABSTRACT

We have the unique opportunity to observe and model nearby streams around the two large Local Group spirals Milky Way and M31 in great detail. However, the detection of streams around other external galaxies is required to verify the general application of the derived results. We give a short summary of streams around other galaxies known in the literature, measuring for the first time the surface brightness of Malin's M83 stream with modern CCD imaging. In addition, we present four new detections of possible stellar streams around disk galaxies.

Motivation & Objective

• To identify and characterize tidal streams around external galaxies to test predictions of hierarchical galaxy formation and minor merger scenarios.
• To overcome the challenge of detecting extremely low-surface-brightness features in extragalactic halos using modern deep imaging techniques.
• To measure the surface brightness of known streams, such as M83’s, with modern CCD data to improve photometric calibration and detectability thresholds.
• To identify new stream candidates through systematic surveys of edge-on spirals and serendipitous deep imaging in public datasets.
• To enable future modeling of stream properties (e.g., age, progenitor mass) by collecting redshifts and calibrated photometry for new detections.

Proposed method

• Conducted deep wide-field imaging of nearby edge-on spiral galaxies using instruments such as the INT/WFC and ESO/WFI to detect low-surface-brightness features.
• Utilized public, deep imaging surveys (e.g., ESO-WFI CDF-S, HST/ACS, ING/WFC) to serendipitously detect tidal streams in random fields.
• Measured surface brightness of M83’s stream using modern CCD data, achieving a limit of μV ≈ 26–27 mag/arcsec².
• Applied photometric and morphological analysis to identify arc-like or tail-like structures consistent with tidal debris from dwarf galaxy accretion.
• Combined redshift data (e.g., 2dF for PGC 751050) and multi-band photometry to assess the physical properties of stream candidates.
• Compared new detections with semianalytic models (e.g., Johnston et al. 2001) to estimate progenitor masses and stream ages.

Experimental results

Research questions

• RQ1 Are tidal streams around external galaxies as common as predicted by hierarchical galaxy formation models?
• RQ2 What is the typical surface brightness of extragalactic tidal streams, and how does it evolve over time?
• RQ3 Can low-surface-brightness tidal features be reliably detected in deep wide-field surveys of isolated spiral galaxies?
• RQ4 How do the morphological and photometric properties of newly detected stream candidates compare to theoretical models of minor merger remnants?
• RQ5 What fraction of detected tidal features arise from minuscule mergers versus more massive interactions?

Key findings

• Four new candidate tidal streams were detected around external disk galaxies—ESO 572-044, PGC 1018343, PGC 751050, and S J160610.7+552700—using deep imaging from public surveys.
• The surface brightness of M83’s tidal stream was measured for the first time with modern CCD imaging, yielding μV ≈ 26–27 mag/arcsec².
• One clear stream candidate (ESO 572-044) was found in a pilot survey of nearby edge-on spirals, while only one additional candidate emerged from a sample of ~80 more distant edge-on disks.
• The stream in PGC 751050, detected in the ESO-WFI CDF-S image, has a redshift of z = 0.1028 and extends over a significant angular scale.
• S J160610.7+552700, a spiral galaxy in the HST/ACS Tadpole field, shows a double-sided stream, suggesting ongoing or recent tidal disruption.
• The study confirms that surface brightness dimming due to cosmological factors (e.g., (1+z)^4) is negligible at 100 Mpc, but still affects detectability at higher redshifts.