- ID:
- ivo://CDS.VizieR/J/ApJ/813/L15
- Title:
- Dwarf galaxies in Fornax cluster from NGFS
- Short Name:
- J/ApJ/813/L15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded u-, g-, and i-band image obtained with the Dark Energy Camera wide-field camera mounted on the 4-m Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the Next Generation Fornax Survey (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii 0.1<r_e_<2.8kpc, and average effective surface brightness values 22.0<{mu}_i_<28.0mag/arcsec2. We confirm the existence of ultra-diffuse galaxies (UDGs) in the Fornax core regions that resemble counterparts recently discovered in the Virgo and Coma galaxy clusters. We also find extremely low surface brightness NGFS dwarfs, which are several magnitudes fainter than the classical UDGs. The faintest dwarf candidate in our NGFS sample has an absolute magnitude of M_i_=-8.0mag. The nucleation fraction of the NGFS dwarf galaxy sample appears to decrease as a function of their total luminosity, reaching from a nucleation fraction of >75% at luminosities brighter than M_i_~=-15.0mag to 0% at luminosities fainter than M_i_~=-10.0mag. The two-point correlation function analysis of the NGFS dwarf sample shows an excess on length scales below ~100 kpc, pointing to the clustering of dwarf galaxies in the Fornax cluster core.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1375
- Title:
- Dwarf galaxies in NGC 1407 Group
- Short Name:
- J/MNRAS/369/1375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NGC 1407 Group stands out among nearby structures by its properties that suggest it is massive and evolved. It shares properties with entities that have been called fossil groups: the 1.4m differential between the dominant elliptical galaxy and the second brightest galaxy comes close to satisfying the definition that has been used to define the fossil class. There are few intermediate-luminosity galaxies, but a large number of dwarfs in the group. We estimate there are 250 group members to the depth of our survey. The slope of the faint end of the luminosity function (reaching M_R_=12) is alpha=-1.35. Velocities for 35 galaxies demonstrate that this group with one dominant galaxy has a mass of 7x10^13^M_{sun}_ and M/L_R_=340M_{sun}_/L_{sun}_. Two galaxies in close proximity to NGC 1407 have very large blueshifts. The most notable is the second brightest galaxy, NGC 1400, with a velocity of 1072km/s with respect to the group mean. We report the detection of X-ray emission from this galaxy and from the group.
- ID:
- ivo://CDS.VizieR/J/AJ/133/715
- Title:
- Dwarf galaxies of the Local Group
- Short Name:
- J/AJ/133/715
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an all-sky, deep optical survey for faint Local Group dwarf galaxies. Candidate objects were selected from the second Palomar Observatory Sky Survey and ESO/Science Research Council survey plates, and follow-up observations were performed to determine whether they were indeed overlooked members of the Local Group. Only two galaxies (Antlia and Cetus) were discovered this way out of 206 candidates. Based on internal and external comparisons, we estimate that our visual survey is more than 77% complete for objects larger than 1' in size and with a surface brightness greater than an extremely faint limit over the 72% of the sky not obstructed by the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/146/104
- Title:
- Dwarf galaxies surface brightness profiles. I.
- Short Name:
- J/AJ/146/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs are flat or increasing out to a break before falling off. Here we re-examine the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single, double, or even triple exponential profiles in up to 11 passbands: GALEX FUV and NUV, ground-based UBVJHK and H{alpha}, and Spitzer 3.6 and 4.5{mu}m. We find that more luminous galaxies have brighter centers, larger inner and outer scale lengths, and breaks at larger radii; dwarf trends with M_B_extend to spirals. However, the V-band break surface brightness is independent of break type, M_B_, and Hubble type. Dwarf Type II and III profiles fall off similarly beyond the breaks but have different interiors and IIs break ~twice as far as IIIs. Outer Type II and III scale lengths may have weak trends with wavelength, but pure Type II inner scale lengths clearly decrease from the FUV to visible bands whereas Type III inner scale lengths increase with redder bands. This suggests the influence of different star formation histories on profile type, but nonetheless the break location is approximately the same in all passbands. Dwarfs continue trends between profile and Hubble types such that later-type galaxies have more Type II but fewer Type I and III profiles than early-type spirals. BCDs and Sms are over-represented as Types III and II, respectively, compared to dIms.
- ID:
- ivo://CDS.VizieR/J/AJ/151/145
- Title:
- Dwarf galaxies surface brightness profiles. II.
- Short Name:
- J/AJ/151/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this second paper of a series, we explore the B-V, U-B, and FUV-NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that the colors of (1) Type I dwarfs generally become redder with increasing radius, unlike spirals which have a blueing trend that flattens beyond ~1.5 disk scale lengths, (2) Type II dwarfs come in six different "flavors", one of which mimics the "U" shape of spirals, and (3) Type III dwarfs have a stretched "S" shape where the central colors are flattish, become steeply redder toward the surface brightness break, then remain roughly constant beyond, which is similar to spiral Type III color profiles, but without the central outward bluing. Faint (-9>M_B_>-14) Type II dwarfs tend to have continuously red or "U" shaped colors and steeper color slopes than bright (-14>M_B_>-19) Type II dwarfs, which additionally have colors that become bluer or remain constant with increasing radius. Sm dwarfs and BCDs tend to have at least some blue and red radial color trend, respectively. Additionally, we determine stellar surface mass density ({Sigma}) profiles and use them to show that the break in {Sigma} generally remains in Type II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs (unlike Type III spirals). Moreover, the break in {Sigma} is strong, intermediate, and weak in faint dwarfs, bright dwarfs, and spirals, respectively, indicating that {Sigma} may straighten with increasing galaxy mass. Finally, the average stellar surface mass density at the surface brightness break is roughly 1-2M_{Sun}_pc^-2^ for Type II dwarfs but higher at 5.9M_{Sun}_pc^-2^ or 27M_{Sun}_pc^-2^ for Type III BCDs and dIms, respectively.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/455
- Title:
- Dwarf galaxy candidates around interacting galaxies
- Short Name:
- J/A+AS/129/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the imaging of a sample of 12 interacting galaxies for which we have catalogued all potential dwarf systems in the vicinity of these strongly interacting galaxies. After careful cleaning of the images and applying a restrictive S/N criterion we have identified, measured and catalogued all possible extended objects in each field. On the frames, covering 11.4x10.5arcmins, on the order of 100 non-stellar, faint, extended objects were found around each interacting galaxy. The vast majority (>98%) of these objects had not been previously identified. The number of expected objects in the magnitude range R=18-19.5 exceeds the expected count of background galaxies. This supports the possibility that a density enhancement of extended objects around some interacting galaxies results from the addition of a locally formed dwarf galaxy population.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/1928
- Title:
- Dwarf galaxy planes in Local Group
- Short Name:
- J/MNRAS/435/1928
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Both major galaxies in the Local Group (LG) are surrounded by thin planes of mostly co-orbiting satellite galaxies, the vast polar structure (VPOS) around the Milky Way (MW) and the Great Plane of Andromeda (GPoA) around M31. We summarize the current knowledge concerning these structures and compare their relative orientations by re-determining their properties in a common coordinate system. The existence of similar, coherent structures around both major LG galaxies motivates an investigation of the distribution of the more distant non-satellite galaxies in the LG. This results in the discovery of two planes (diameters of 1-2Mpc) which contain almost all nearby non-satellite galaxies. The two LG planes are surprisingly symmetric. They are inclined by only 20{deg} relative to the galactic disc of M31, are similarly thin (heights of {approx}60kpc) and have near-to-identical offsets from the MW and from M31. They are inclined relative to each other by 35{deg}. Comparing the plane orientations with each other and with additional features reveals indications for an intimate connection between the VPOS and the GPoA. They are both polar with respect to the MW, have similar orbital directions and are inclined by about 45{deg}+/-7{deg} relative to each other. The Magellanic Stream approximately aligns with the VPOS and the GPoA, but also shares its projected position and line-of-sight velocity trend with a part of the dominating structure of non-satellite dwarf galaxies. In addition, the recent proper motion measurement of M31 indicates a prograde orbit of the MW-M31 system, the VPOS and the GPoA. The alignment with other features such as the Supergalactic Plane and the overdensity in hypervelocity stars are discussed as well. We end with a short summary of the currently proposed scenarios trying to explain the LG galaxy structures as either originating from cosmological structures or from tidal debris of a past galaxy encounter. We emphasize that there currently exists no full detailed model which satisfactorily explains the existence of the thin symmetric LG planes.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A92
- Title:
- Dwarf spheroidal galaxies in CenA group
- Short Name:
- J/A+A/645/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dwarf spheroidal galaxies (dSphs) have been extensively investigated in the Local Group, but their low luminosity and surface brightness make similar work in more distant galaxy groups challenging. Modern instrumentation unlocks the possibility of scrutinizing these faint systems in other environments, expanding the parameter space of group properties. We use MUSE spectroscopy to study the properties of 14 known or suspected dSph satellites of Cen A. Twelve targets are confirmed to be group members based on their radial velocities. Two targets are background galaxies at ~50Mpc: KK 198 is a face-on spiral galaxy, and dw1315-45 is an ultra-diffuse galaxy with an effective radius of ~2300pc. The 12 confirmed dSph members of the Cen A group have old and metal-poor stellar populations and follow the stellar metallicity-luminosity relation defined by the dwarf galaxies in the Local Group. In the three brightest dwarf galaxies (KK 197, KKs 55, and KKs 58), we identify globular clusters, as well as a planetary nebula in KK197, although its association with this galaxy and/or the extended halo of Cen A is uncertain. Using four discrete tracers, we measure the velocity dispersion and dynamical mass of KK197. This dSph appears dark matter dominated and lies on the radial acceleration relation of star-forming galaxies within the uncertainties. It also is consistent with predictions stemming from modified Newtonian dynamics (MOND). Surprisingly, in the dwarf KK203 we find an extended H ring. Careful examination of Hubble Space Telescope photometry reveals a very low level of star formation at ages between 30-300Myr. The H{alpha} emission is most likely linked to a ~40Myr old supernova remnant, although other possibilities for its origin cannot be entirely ruled out.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/85
- Title:
- Dynamical masses of z~2 quiescent galaxies
- Short Name:
- J/ApJ/771/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using stellar kinematics measurements, we investigate the growth of massive, quiescent galaxies from z~2 to today. We present X-Shooter spectra from the UV to NIR and dynamical mass measurements of five quiescent massive (>10^11^M_{sun}_) galaxies at z~2. This triples the sample of z>1.5 galaxies with well-constrained ({delta}{sigma}<100km/s) velocity dispersion measurements. From spectral population synthesis modeling we find that these galaxies have stellar ages that range from 0.5 to 2Gyr, with no signs of ongoing star formation. We measure velocity dispersions (290-450km/s) from stellar absorption lines and find that they are 1.6-2.1 times higher than those of galaxies in the Sloan Digital Sky Survey at the same mass. Sizes are measured using GALFIT from Hubble Space Telescope Wide Field Camera 3 H_160_ and UDS K-band images. The dynamical masses correspond well to the spectral energy distribution based stellar masses, with dynamical masses that are ~15% higher.
- ID:
- ivo://CDS.VizieR/J/MNRAS/363/769
- Title:
- Dynamical modelling of 4 early-type galaxies
- Short Name:
- J/MNRAS/363/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse long-slit spectra of four early-type galaxies which extend from ~1 to 3 effective radii: IC 1459; IC 3370; NGC 3379 and NGC 4105. We have extracted the full line-of-sight velocity distribution (in the case of NGC 3379 we also used data from the literature), which we model using the two-integral approach. Using two-integral modelling, we find no strong evidence for dark haloes, but the fits suggest that three-integral modelling is necessary. We also find that the inferred constant mass-to-light ratio in all the four cases is typical for early-type galaxies. Finally, we also discuss the constraints on the mass-to-light ratio, which can be obtained using X-ray haloes in the case of IC 1459, NGC 3379 and NGC 4105, and compare the estimated values with the predictions from the dynamical modelling.
