Multiparametric scaling relations for dwarf irregular galaxies in different environments

AbstractWe study the correlations of rotation velocity and absolute magnitude with surface brightness for low surface brightness dwarf irregular galaxies (dIrrs). We find that isolated objects contribute most to the scatter in the Tully–Fisher relation (TFR). Excluding these extreme cases, we develop a three-parameter (luminosity, Hi line width at 20% of peak flux level, i.e., W20, effective surface brightness) TFR for 60 dIrrs (with revised Hubble type T > 8) in the Local Volume (LV) with Cepheid and tip-of-the-red-giant-branch distance measurements. The relation is applied to galaxies of the same morphological type with radial velocities vLG ≤ 3500 km s−1 in the Local Supercluster. We obtained surface photometry and determined structural parameters using sdss images. The rotational velocities and derived photometric parameters for most galaxies in small groups agree well with those corresponding to the three-parameter TFR. However, isolated galaxies appear to have systematically lower surface brightnesses and longer scale lengths for the same luminosity than galaxies in small groups. This may indicate on average twice larger Hi-to-optical disk size ratios for our sample of isolated dIrrs, because their Hi surface densities calculated using the optical diameters look normal.

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The Fornax Deep Survey with the VST

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935433 ◽

2019 ◽

Vol 628 ◽

pp. A4 ◽

Cited By ~ 6

Author(s):

M. A. Raj ◽

E. Iodice ◽

N. R. Napolitano ◽

M. Spavone ◽

H-S. Su ◽

...

Keyword(s):

Surface Brightness ◽

Structural Parameters ◽

Absolute Magnitude ◽

Morphological Type ◽

High Density ◽

Molecular Gas ◽

Type Ii ◽

Type Iii ◽

Deep Survey ◽

Fornax Cluster

Context. We present the study of a magnitude limited sample (mB ≤ 16.6 mag) of 13 late type galaxies (LTGs), observed inside the virial radius, Rvir ∼ 0.7 Mpc, of the Fornax cluster within the Fornax Deep Survey (FDS). Aims. The main objective is to use surface brightness profiles and g − i colour maps to obtain information on the internal structure of these galaxies and find signatures of the mechanisms that drive their evolution in high-density environments inside the virial radius of the cluster. Methods. By modelling galaxy isophotes, we extract the azimuthally averaged surface brightness profiles in four optical bands. We also derive g − i colour profiles, and relevant structural parameters like total magnitude and effective radius. For ten of the galaxies in this sample, we observe a clear discontinuity in their typical exponential surface brightness profiles, derive their “break radius”, and classify their disc-breaks into Type II (down-bending) or Type III (up-bending). Results. We find that Type II galaxies have bluer average (g − i) colour in their outer discs while Type III galaxies are redder. The break radius increases with stellar mass and molecular gas mass while it decreases with molecular gas-fractions. The inner and outer scale-lengths increase monotonically with absolute magnitude, as found in other works. For galaxies with CO(1-0) measurements, there is no detected cold gas beyond the break radius (within the uncertainties). In the context of morphological segregation of LTGs in clusters, we also find that, in Fornax, galaxies with morphological type 5 < T ≤ 9 (∼60% of the sample) are located beyond the high-density, ETG-dominated regions, however there is no correlation between T and the disc-break type. We do not find any correlation between the average (g − i) colours and cluster-centric distance, but the colour-magnitude relation holds true. Conclusions. The main results of this work suggest that the disc-breaks of LTGs inside the virial radius of the Fornax cluster seem to have arisen through a variety of mechanisms (e.g. ram-pressure stripping, tidal disruption), which is evident in their outer-disc colours and the absence of molecular gas beyond their break radius in some cases. This can result in a variety of stellar populations inside and outside the break radii.

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Erratum: Surface Photometry of Low Surface Brightness Dwarf Irregular Galaxies

The Astrophysical Journal Supplement Series ◽

10.1086/313122 ◽

1998 ◽

Vol 117 (2) ◽

pp. 633-634 ◽

Cited By ~ 1

Author(s):

Richard J. Patterson ◽

Trinh X. Thuan

Keyword(s):

Surface Brightness ◽

Surface Photometry ◽

Irregular Galaxies ◽

Low Surface Brightness ◽

Dwarf Irregular Galaxies

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Truncated disc surface brightness profiles produced by flares

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316009200 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 272-272

Author(s):

Alejandro Borlaff ◽

M. Carmen Eliche-Moral ◽

John Beckman ◽

Joan Font

Keyword(s):

Surface Brightness ◽

Structural Parameters ◽

Morphological Type ◽

Hubble Sequence ◽

Wide Range ◽

The Face ◽

Analogous Model ◽

Galaxy Model ◽

Realistic Images ◽

Real Type

AbstractPrevious studies have discarded that flares in galactic discs may explain the truncation that are frequently observed in highly-inclined galaxies (Kregel et al. 2002). However, no study has systematically analysed this hypothesis using realistic models for the disc, the flare and the bulge. We derive edge-on and face-on surface brightness profiles for a series of realistic galaxy models with flared discs that sample a wide range of structural and photometric parameters across the Hubble Sequence, accordingly to observations. The surface brightness profile for each galaxy model has been simulated for edge-on and face-on views to find out whether the flared disc produces a significant truncation in the disc in the edge-on view compared to the face-on view or not. In order to simulate realistic images of disc galaxies, we have considered the observational distribution of the photometric parameters as a function of the morphological type for three mass bins (10 < log10(M/M⊙) < 10.7, 10.7 < log10(M/M⊙) < 11 and log10(M/M⊙) > 11), and four morphological type bins (S0–Sa, Sb–Sbc, Sc–Scd and Sd–Sdm). For each mass bin, we have restricted the photometric and structural parameters of each modelled galaxy to their characteristic observational ranges (μ0, disc, μeff, bulge, B/T, Mabs, reff, nbulge, hR, disc) and the flare in the disc (hz, disc/hR, disc, ∂hz, disc/∂R, see de Grijs & Peletier 1997, Graham 2001, López-Corredoira et al. 2002, Yoachim & Dalcanton 2006, Bizyaev et al. 2014, Mosenkov et al. 2015).Contrary to previous claims, the simulations show that realistic flared disks can be responsible for the truncations observed in many edge-on systems, preserving the profile of the non-flared analogous model in face-on view. These breaks reproduce the properties of the weak-to-intermediate breaks observed in many real Type-II galaxies in the diagram relating the radial location of the break (RbrkII) in units of the inner disk scale-length with the break strength S (Laine et al. 2014). Radial variation of the scale-height of the disc (flaring) can explain the existence of many breaks in edge-on galaxies, especially of those with low break strengths $S=\log _{10}\frac{h_{o}}{h_{i}} \sim \ [-0.3,-0.1]$.

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A new measurement of the Hubble constant using Type Ia supernovae calibrated with surface brightness fluctuations

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039196 ◽

2021 ◽

Vol 647 ◽

pp. A72 ◽

Cited By ~ 3

Author(s):

Nandita Khetan ◽

Luca Izzo ◽

Marica Branchesi ◽

Radosław Wojtak ◽

Michele Cantiello ◽

...

Keyword(s):

Surface Brightness ◽

Hubble Constant ◽

Absolute Magnitude ◽

Host Galaxy ◽

Type Ia Supernovae ◽

Distance Measurements ◽

Surface Brightness Fluctuations ◽

Type Ia ◽

Red Giant ◽

Ia Supernovae

We present a new calibration of the peak absolute magnitude of Type Ia supernovae (SNe Ia) based on the surface brightness fluctuations (SBF) method, aimed at measuring the value of the Hubble constant. We build a sample of calibrating anchors consisting of 24 SNe hosted in galaxies that have SBF distance measurements. Applying a hierarchical Bayesian approach, we calibrate the SN Ia peak luminosity and extend the Hubble diagram into the Hubble flow by using a sample of 96 SNe Ia in the redshift range 0.02 < z < 0.075, which was extracted from the Combined Pantheon Sample. We estimate a value of H0 = 70.50 ± 2.37 (stat.) ± 3.38 (sys.) km s−1 Mpc−1 (i.e., 3.4% stat., 4.8% sys.), which is in agreement with the value obtained using the tip of the red giant branch calibration. It is also consistent, within errors, with the value obtained from SNe Ia calibrated with Cepheids or the value inferred from the analysis of the cosmic microwave background. We find that the SNe Ia distance moduli calibrated with SBF are on average larger by 0.07 mag than those calibrated with Cepheids. Our results point to possible differences among SNe in different types of galaxies, which could originate from different local environments and/or progenitor properties of SNe Ia. Sampling different host galaxy types, SBF offers a complementary approach to using Cepheids, which is important in addressing possible systematics. As the SBF method has the ability to reach larger distances than Cepheids, the impending entry of the Vera C. Rubin Observatory and JWST into operation will increase the number of SNe Ia hosted in galaxies where SBF distances can be measured, making SBF measurements attractive for improving the calibration of SNe Ia, as well as in the estimation of H0.

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Structural analysis of massive galaxies using HST deep imaging at z < 0.5

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936276 ◽

2020 ◽

Vol 634 ◽

pp. A11

Author(s):

Sandra N. dos Reis ◽

Fernando Buitrago ◽

Polychronis Papaderos ◽

Israel Matute ◽

José Afonso ◽

...

Keyword(s):

Surface Brightness ◽

Structural Parameters ◽

Structural Evolution ◽

Morphological Type ◽

Formation Mechanisms ◽

Massive Galaxies ◽

Local Mass ◽

Mass Size ◽

Mass Assembly ◽

Size Relation

Context. The most massive galaxies (Mstellar ≥ 1011 M⊙) in the local Universe are characterized by a bulge-dominated morphology and old stellar populations, in addition to being confined to a tight mass-size relation. Identifying their main components can provide insights into their formation mechanisms and subsequent mass assembly. Aims. Taking advantage of Hubble Space Telescope (HST) CANDELS data, we analyze the lowest redshift (z < 0.5) massive galaxies in the H and I band in order to disentangle their structural constituents and study possible faint non-axisymmetric features. Methods. Our final sample consists of 17 massive galaxies. Due to the excellent HST spatial resolution for intermediate redshift objects, they are hard to model by purely automatic parametric fitting algorithms. We performed careful single and double (bulge-disk decompositions) Sérsic fits to their galaxy surface brightness profiles. We compare the model color profiles with the observed ones and also derive multi-component global effective radii attempting to obtain a better interpretation of the mass-size relation. Additionally, we test the robustness of our measured structural parameters via simulations. Results. We find that the Sérsic index does not offer a good proxy for the visual morphological type for our sample of massive galaxies. Our derived multi-component effective radii give a better description of the size of our sample galaxies than those inferred from single Sérsic models with GALFIT. Our galaxy population lies on the scatter of the local mass-size relation, indicating that these massive galaxies have not experienced a significant growth in size since z ∼ 0.5. Interestingly, the few outliers are late-type galaxies, indicating that spheroids must reach the local mass-size relation earlier. For most of our sample galaxies, both single- and multi-component Sérsic models with GALFIT show substantial systematic deviations from the observed surface brightness profiles in the outskirts. These residuals may be partly due to several factors, namely a nonoptimal data reduction for low surface brightness features or the existence of prominent stellar haloes for massive galaxies, or they could also arise from conceptual shortcomings of parametric 2D image decomposition tools. They consequently propagate into galaxy color profiles. This is a significant obstacle to the exploration of the structural evolution of galaxies, which calls for a critical assessment and refinement of existing surface photometry techniques.

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Morphological aspects of star formation in dwarf galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100054427 ◽

1999 ◽

Vol 171 ◽

pp. 261-270

Author(s):

Noah Brosch ◽

Ana Heller ◽

Elchanan Almoznino

Keyword(s):

Star Formation ◽

Surface Brightness ◽

High Surface ◽

Dark Matter Halo ◽

Star Forming ◽

Star Forming Regions ◽

Tidal Interactions ◽

Irregular Galaxies ◽

Asymmetric Pattern ◽

Dwarf Irregular Galaxies

AbstractWe studied the morphology of star formation in dwarf irregular galaxies and found that, in general, this takes place on one side of a galaxy and far from the center. This is mainly true for low surface brightness galaxies; in high surface brightness dwarf irregulars the star formation tends to be more centrally concentrated, as well as being more intense. We discuss possible star formation triggers in dwarf irregular galaxies, and evaluate the reasons for the peculiar distribution of star forming regions of these galaxies. Stochastic star formation, interactions with external gas, and tidal interactions appear to be ruled out as responsible for the asymmetric pattern of star formation. We conclude that asymmetry of a dark matter halo or of an asymmetric underlying stellar distribution may trigger an asymmetric pattern of star formation.

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