The metal-poor dwarf irregular galaxy candidate next to Mrk 1172

Lassen, Augusto E; Riffel, Rogério; Chies-Santos, Ana L.; Johnston, Evelyn J.; Häußler, Boris; Azevedo, Gabriel M; Ruschel-Dutra, D.; Riffel, Rogemar A.

doi:10.1093/mnras/stab1838

Cited by 3 publications

(1 citation statement)

References 77 publications

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“…There are many indirect observational evidences of gas accretion (Cresci et al 2010;Sánchez Almeida et al 2014). For example, the metallicity inhomogeneities, particularly the combination of phenomena of metallicity dropping and intense starbursts, as observed in some blue compact dwarf (BCD) galaxies, could be one piece of evidence of cold-flow accretion (Crain et al 2009;Sánchez Almeida et al 2015;Mannucci et al 2010;Lassen et al 2021). There are simulations that can reproduce this phenomenon as well, in that the external gas accreted by host galaxies can lower the metallicity of star-forming gas and trigger the star formation simultaneously (Yates et al 2012).…”

Section: Introductionmentioning

confidence: 99%

MaNGA 8313-1901: Gas Accretion Observed in a Blue Compact Dwarf Galaxy?

Yin

Liu

et al. 2022

ApJ

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Gas accretion is an important process in the evolution of galaxies, but it has limited direct observational evidences. In this paper, we report the detection of a possible ongoing gas accretion event in a blue compact dwarf (BCD) galaxy, MaNGA 8313-1901, observed by the Mapping Nearby Galaxies and Apache Point Observatory (MaNGA) program. This galaxy has a distinct off-centered blue clump to the northeast (the NE clump) that shows low metallicity and enhanced star formation. The kinematics of the gas in the NE clump also seems to be detached from the host BCD galaxy. Together with the metallicity drop of the NE clump, it suggests that the NE clump likely has an external origin, such as gas accretion or galaxy interaction, rather than an internal origin, such as an H II complex in the disk. After removing the underlying host component, we find that the spectrum of the “pure” clump can match very well with a modeled spectrum containing a stellar population of the young stars (≤7 Myr) only. This may imply that the galaxy is experiencing an accretion of cold gas, instead of a merger event involving galaxies with significant preexisting old stars. We also find signs of another clump (the SW clump) at the southwest corner of the host galaxy, and the two clumps may share the same origin of gas accretion.

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Section: Introductionmentioning

confidence: 99%

MaNGA 8313-1901: Gas Accretion Observed in a Blue Compact Dwarf Galaxy?

Yin

Liu

et al. 2022

ApJ

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Bulgeless disks, dark galaxies, inverted color gradients, and other expected phenomena at higher z

Papaderos¹,

Östlin²,

Breda³

2023

A&A

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The spectral energy distribution (SED) of galaxies varies both between galaxies and within them. For instance, early-type spiral galaxies have a red bulge surrounded by a bluer star-forming disk with H II regions within. When observing redshifted galaxies, a given photometric filter probes light at a bluer rest frame, and in relating the observed magnitudes to the rest frame of the filter, so-called k corrections are commonly applied to account for the relative dimming or brightening in addition to the pure distance effect. The amount of correction depends on the shape of the spectrum (SED), so different k corrections apply to galaxies of different spectral types. This is, however, only part of the story, since any galaxy with a spatially non-homogeneous SED will experience a spatially varying relative dimming or brightening as a function of observed wavelength. Also, the morphological appearance of galaxies will therefore change with redshift. For instance, an early spiral galaxy observed in the V band would show a prominent bulge at z = 0, whereas, if at redshift z ∼ 1, the V filter probes emission in the rest-frame near-ultraviolet where the bulge is faint and the disk relatively brighter, thus the galaxy may appear as bulgeless. One popular way of studying spatial variations in the stellar population and dust content of galaxies is the use of color maps. For star-forming galaxies that have an appreciable contribution from nebular emission (lines and continuum), an additional effect is that the shifting of strong features in or out of filters will result in a non-monotonous color evolution with redshift. Hence, unlike the effects of distance, cosmological surface brightness dimming, and gravitational lensing, which are all achromatic, the fact that most galaxies have a spatially varying SED leads to a chromatic surface brightness modulation (CMOD) with redshift. While the CMOD effects are in principle easy to grasp, they affect multicolor imaging surveys and photometric properties derived from such surveys in a complex fashion. Properties such as the bulge-to-disk ratio, Sérsic exponent, light concentration, asymmetry index and effective radius, radial color gradients, and stellar mass determinations from SED fitting will depend on the redshift, the filters employed, and the rest-frame 2D SED patterns in a galaxy and will bias results inferred on galaxy evolution across cosmic time (e.g., the evolution of the mass-size, bulge-supermassive black hole, and Tully-Fisher relation), and potentially also weak lensing, if these effects are not properly taken into account. In this article we quantify the CMOD effects for idealized galaxies built from spectral synthesis models and from galaxies with observed integral field spectroscopy, and we show that they are significant and should be taken into account in studies of resolved galaxy properties and their evolution with redshift.

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Dwarf galaxy discoveries from the KMTNet supernova programme – III. The Milky-Way analogue NGC 2997 group

Fan,

Moon,

Park

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We present the discovery of 48 new and the analysis of 55, including 7 previously discovered, dwarf galaxy candidates around the giant spiral galaxy NGC 2997 using deep BVI images from the KMTNet Supernova Program. Their V-band central surface brightness and total absolute magnitudes are in the range of 20.3–26.7 mag arcsec−2 and –(8.02–17.69) mag, respectively, while the I-band effective radii are 0.14–2.97 kpc. We obtain α ≃ –1.43 ± 0.02 for the faint-end slope of their luminosity function, comparable to previously measured values but shallower than theoretical predictions based on ΛCDM models. The distance-independent distributions of their mass and color suggest that the group could have recently accreted new massive members from the surrounding fields. The systematically bluer colors of the brighter members indicate younger stellar population and higher star formation activities in them, which appears to be consistent with similar findings from the SAGA or ELVES survey. We suggest that the massive and bluer dwarf galaxies in the group have experienced less environmental quenching due to their recent accretion, while environmental quenching has been more effective for the low-mass members. The interpretation of NGC 2997 being populationally young with recent accretion of massive members is also consistent with the overall morphological distribution of the dwarf galaxies showing a lack of morphologically evolved candidates but a plethora of irregularly shaped ones. Our detection rate of dwarf galaxy candidates in the NGC 2997 group and their inferred star formation activities are comparable to those found in Milky Way analog systems from recent surveys within the magnitude limit MV ≲ –13 mag.

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The metal-poor dwarf irregular galaxy candidate next to Mrk 1172

Cited by 3 publications

References 77 publications

MaNGA 8313-1901: Gas Accretion Observed in a Blue Compact Dwarf Galaxy?

MaNGA 8313-1901: Gas Accretion Observed in a Blue Compact Dwarf Galaxy?

Bulgeless disks, dark galaxies, inverted color gradients, and other expected phenomena at higher z

Dwarf galaxy discoveries from the KMTNet supernova programme – III. The Milky-Way analogue NGC 2997 group

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