Resolved Stellar Streams around NGC 4631 from a Subaru/Hyper Suprime-Cam Survey

Tanaka, Mikito; Komiyama, Yutaka

doi:10.3847/1538-4357/aa6d11

Cited by 22 publications

(25 citation statements)

References 52 publications

(90 reference statements)

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“…It is an interesting fact, that the derived oxygen abundance of [M/H] = −0.90 in Spur 2 matches almost exactly the metallicity derived for the stellar stream ([M/H] = −0.92; Tanaka et al 2017). The uncertainty for the stellar abundance is quite large, however, with a 90 percent confidence interval between −1.46 and −0.51 (see Tanaka et al 2017). Therefore, this apparent similarity does not provide strong constraints on a possible common origin.…”

Section: Ngc 4627 or Other Satellite Galaxiessupporting

confidence: 67%

Circumgalactic Gas at Its Extreme: Tidal Gas Streams around the Whale Galaxy NGC 4631 Explored with HST/COS

Richter

Winkel

Wakker

et al. 2018

ApJ

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We present a detailed analysis of the absorption properties of one of the tidal gas streams around the "Whale" galaxy NGC 4631 in the direction of the quasar 2MASS J12421031+3214268. Our study is based on ultraviolet spectral data obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and 21cm-data from the HALOGAS project and the Green Bank Telescope (GBT). We detect strong H i Ly α absorption in the velocity range +550 to +800 km s −1 related to gas from a NGC 4631 tidal stream known as Spur 2. We measure a column density of log (N (H i/cm −2 )) = 18.68 ± 0.15, indicating that the quasar sightline traces the outer boundary of Spur 2 as seen in the 21cm data. Metal absorption in Spur 2 is detected in the lines of O i, C ii, Si ii, and Si iii in a complex absorption pattern that reflects the multi-phase nature of the gas. We find that the average neutral gas fraction in Spur 2 towards 2MASS J12421031+3214268 is only 14 percent. This implies that ionized gas dominates the total mass of Spur 2, which then may comprise more than 10 9 M ⊙ . No significant depletion of Si is observed, showing that Spur 2 does not contain significant amounts of dust. From the measured O i/H i column-density ratio we determine an α abundance in Spur 2 of 0.13 +0.07 −0.05 solar ([α/H] = −0.90 ± 0.16), which is substantially lower than what is observed in the NGC 4631 disk. The low metallicity and low dust content suggest that Spur 2 represents metal-deficient gas stripped off a gas-rich satellite galaxy during a recent encounter with NGC 4631.

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Section: Ngc 4627 or Other Satellite Galaxiessupporting

confidence: 67%

Circumgalactic Gas at Its Extreme: Tidal Gas Streams around the Whale Galaxy NGC 4631 Explored with HST/COS

Richter

Winkel

Wakker

et al. 2018

ApJ

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“…This is roughly consistent with the estimate from considering the subpopulation of LV satellites around the MW, M31, CenA, and M81 where satellites of much fainter surface brightness are discoverable via resolved stars. Additionally, using the extremely deep HSC data (∼10 hours of integration on Subaru) from Tanaka et al (2017) for one ELVES host (NGC 4631), we do not find any additional satellites in the ELVES completeness range 14 .…”

Section: Size Distributionsmentioning

confidence: 66%

Structures of Dwarf Satellites of Milky Way-like Galaxies: Morphology, Scaling Relations, and Intrinsic Shapes

Carlsten

Greene

Greco

et al. 2021

ApJ

101

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The structure of a dwarf galaxy is an important probe of the effects of stellar feedback and environment. Using an unprecedented sample of 223 low-mass satellites from the ongoing Exploration of Local Volume Satellites survey, we explore the structures of dwarf satellites in the mass range 105.5 < M ⋆ < 108.5 M ⊙. We survey satellites around 80% of the massive, M K < − 22.4 mag, hosts in the Local Volume (LV). Our sample of dwarf satellites is complete to luminosities of M V <−9 mag and surface brightness μ 0,V < 26.5 mag arcsec−2 within at least ∼200 projected kpc of the hosts. For this sample, we find a median satellite luminosity of M V = −12.4 mag, median size of r e = 560 pc, median ellipticity of ϵ = 0.30, and median Sérsic index of n = 0.72. We separate the satellites into late- and early-type (29.6% and 70.4%, respectively). The mass–size relations are very similar between them within ∼5%, which indicates that the quenching and transformation of a late-type dwarf into an early-type one involves only very mild size evolution. Considering the distribution of apparent ellipticities, we infer the intrinsic shapes of the early- and late-type samples. Combining with literature samples, we find that both types of dwarfs are described roughly as oblate spheroids that get more spherical at fainter luminosities, but early-types are always rounder at fixed luminosity. Finally, we compare the LV satellites with dwarf samples from the cores of the Virgo and Fornax clusters. We find that the cluster satellites show similar scaling relations to the LV early-type dwarfs but are roughly 10% larger at fixed mass, which we interpret as being due to tidal heating in the cluster environments. The dwarf structure results presented here are a useful reference for simulations of dwarf galaxy formation and the transformation of dwarf irregulars into spheroidals.

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“…NGC 4631. Tanaka et al (2017) studied the interacting galaxy system NGC 4631 and NGC 4656 and identified 11 dwarf galaxies and two tidal streams in its outer region based on the stellar density maps divided into resolved stellar populations. Seth et al (2005) found somewhat thickened disc structures via HST/ACS observations.…”

Section: Resultsmentioning

confidence: 99%

The haloes and environments of nearby galaxies (HERON) – II. The outer structure of edge-on galaxies

Mosenkov

Rich

Koch

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The HERON project is aimed at studying halos and low surface brightness details near galaxies. In this second HERON paper we consider in detail deep imaging (down to surface brightness of ∼ 28 mag/arcsec 2 in the r band) for 35 galaxies, viewed edgeon. We confirm a range of low surface brightness features previously described in the literature but also report new ones. We classify the observed outer shapes of the galaxies into three main types (and their prototypes): disc/diamond-like (NGC 891), oval (NGC 4302), and boxy (NGC 3628). We show that the shape of the outer disc in galaxies does not often follow the general 3D model of an exponential disc: 17 galaxies in our sample exhibit oval or even boxy isophotes at the periphery. Also, we show that the less flattened the outer disc is, the more oval or boxy its structure. Many galaxies in our sample have an asymmetric outer structure. We propose that the observed diversity of the galaxy outer shapes is defined by the merger history and its intensity: if no recent multiple minor or single major merging took place, the outer shape is diamond-like or discy. On the contrary, interacting galaxies show oval outer shapes, whereas recent merging appears to transform the outer shape to boxy.

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Resolved Stellar Streams around NGC 4631 from a Subaru/Hyper Suprime-Cam Survey

Cited by 22 publications

References 52 publications

Circumgalactic Gas at Its Extreme: Tidal Gas Streams around the Whale Galaxy NGC 4631 Explored with HST/COS

Circumgalactic Gas at Its Extreme: Tidal Gas Streams around the Whale Galaxy NGC 4631 Explored with HST/COS

Structures of Dwarf Satellites of Milky Way-like Galaxies: Morphology, Scaling Relations, and Intrinsic Shapes

The haloes and environments of nearby galaxies (HERON) – II. The outer structure of edge-on galaxies

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