Extragalactic planetary nebulae (PNe) offer a way to determine the distance to their host galaxies thanks to the nearly universal shape of the luminosity function (PNLF). Accurate PNe distance measurements rely on obtaining well- sampled PNLFs and the number of observed PNe scales with the encompassed stellar mass. This means either disposing of wide-field observations or on focusing on the bright central regions of galaxies. In this work we take this second approach and conduct a census of the PNe population in the central regions of galaxies in the Fornax cluster, using VLT/MUSE data for the early- type galaxies observed over the course of the Fornax3D survey. Using such integral-field spectroscopic observations to carefully separate the nebular emission from the stellar continuum, we isolate [OIII] 5007{AA} sources of interest, filter out unresolved impostor sources or kinematic outliers, and present a catalogue of 1350 unique PNe sources across 21 early- type galaxies, which includes their positions, [OIII} 5007{AA} line magnitudes and line-of-sight velocities. Using the PNe catalogued within each galaxy, we present independently-derived distance estimates based on the fit to the entire observed PNLF observed while carefully accounting for the PNe detection incompleteness. With these individual measurements we arrive at an average distance to the Fornax cluster itself of 19.86+/-0.32Mpc ({mu}_PNLF_=31.49+/-0.04mag). Our PNLF distance measurements agree well with previous distances based on surface brightness fluctuations, finding no significant systematic offsets between the two methods as otherwise reported in previous studies.
Globular clusters (GCs) are found ubiquitously in massive galaxies and due to their old ages, they are regarded as fossil records of galaxy evolution. Spectroscopic studies of GC systems are often limited to the outskirts of galaxies, where GCs stand out against the galaxy background and serve as bright tracers of galaxy assembly. In this work we use the capabilities of the Multi Unit Explorer Spectrograph (MUSE) to extract a spectroscopic sample of 722 GCs in the inner regions (<3Reff) of 32 galaxies in the Fornax cluster. These galaxies were observed as part of the Fornax 3D project, a MUSE survey that targets early and late-type galaxies within the virial radius of Fornax. After accounting for the galaxy background in the GC spectra, we extracted line-of-sight velocities and determined metallicities of a subsample of 238 GCs. We found signatures of rotation within GC systems and comparing the GC kinematics and that of the stellar body shows that the angular momentum of the GC system reflects that of the stars, confirming the usefulness of GCs as kinematic tracers. While the red GCs prove to closely follow the metallicity profile of the host galaxy, the blue GCs show a large spread of metallicities but are generally more metal -poor than the host.
The globular cluster H4, located in the center of the Fornax dwarf spheroidal galaxy, is crucial for understanding the formation and chemical evolution of star clusters in low-mass galactic environments. H4 is peculiar because the cluster is significantly more metal-rich than the galaxy's other clusters, is located near the galaxy center, and may also be the youngest cluster in the galaxy. In this study, we present detailed chemical abundances derived from high-resolution (R~28000) spectroscopy of an isolated H4 member star for comparison with a sample of 22 nearby Fornax field stars. We find the H4 member to be depleted in the alpha-elements Si, Ca, and Ti with [Si/Fe]=-0.35+/-0.34, [Ca/Fe]=+0.05+/-0.08, and [Ti/Fe]=-0.27+/-0.23, resulting in an average [{alpha}/Fe]=-0.19+/-0.14. If this result is representative of the average cluster properties, H4 is the only known system with a low [{alpha}/Fe] ratio and a moderately low metallicity embedded in an intact birth environment. For the field stars we find a clear sequence, seen as an early depletion in [{alpha}/Fe] at low metallicities, in good agreement with previous measurements. H4 falls on top of the observed field star [{alpha}/Fe] sequence and clearly disagrees with the properties of Milky Way halo stars. We therefore conclude that within a galaxy, the chemical enrichment of globular clusters may be closely linked to the enrichment pattern of the field star population. The low [{alpha}/Fe] ratios of H4 and similar metallicity field stars in Fornax give evidence that slow chemical enrichment environments, such as dwarf galaxies, may be the original hosts of alpha-depleted clusters in the halos of the Milky Way and M31.
We present a panoramic study of the Fornax dwarf spheroidal galaxy, using data obtained as part of the VLT Survey Telescope (VST) ATLAS Survey. The data presented here - a subset of the full survey - uniformly cover a region of 25deg^2^ centred on the galaxy, in g, r and i bands. This large area coverage reveals two key differences to previous studies of Fornax. First, data extending beyond the nominal tidal radius of the dwarf highlight the presence of a second distinct red giant branch population. This bluer red giant branch appears to be co-eval with the horizontal branch population. Secondly, a shell structure located approximately 1.4{deg} from the centre of Fornax is shown to be a mis-identified background overdensity of galaxies. This last result casts further doubt on the hypothesis that Fornax underwent a gas-rich merger in its relatively recent past.
We use the very deep and homogeneous I-band selected dataset of the FORS Deep Field (FDF) to trace the evolution of the luminosity function over the redshift range 0.5<z<5.0. We show that the FDF I-band selection down to I_AB_=26.8 misses of the order of 10% of the galaxies that would be detected in a K-band selected survey with magnitude limit K_AB_=26.3 (like FIRES). Photometric redshifts for 5558 galaxies are estimated based on the photometry in 9 filters (U, B, Gunn g, R, I, SDSS z, J, K and a special filter centered at 834nm).
We present low resolution multi-object spectroscopy of an I-band magnitude limited (I_AB_~23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscopic targets in the HST-WFPC2 HDFS were supplemented with galaxies detected in the Infrared Space Observatory's survey of the HDFS and the ESO Imaging Deep Survey to comprise a sample of 100 galaxies for spectroscopic observations. Based on detections of several emission lines, such as [OII]3727, H{beta} and [OIII]5007, or of other spectroscopic features, we measured accurate redshifts for 50 objects in the central HDFS and flanking fields. The redshift range of the current sample of galaxies is 0.6-1.2, with a median redshift of 1.13 (at I~23.5 not corrected for completeness). The sample is dominated by starburst galaxies with only a small fraction of ellipticals (~10%). For the emission line objects, the extinction corrected [OII]3727 line strengths yield estimates of star formation rates in the range 0.5-30M_{sun}_/yr. We used the present data to derive the [OII]3727 luminosity function up to redshift of 1.2. When combined with [OII]3727 luminosity densities for the local and high redshift Universe, our results confirm the steep rise in the star formation rate (SFR) to z~1.3.
We present the results of the analysis of deep archival XMM-Newton observations towards the dwarf spheroidal galaxies Draco, Leo I, Ursa Major II (UMa II) and Ursa Minor (UMi) in the Milky Way neighbourhood. The X-ray source population is characterized and cross-correlated with available databases to infer their nature. We also investigate if intermediate-mass black holes are hosted in the centre of these galaxies. For Draco, we detect 96 high-energy sources, two of them possibly being local stars, while no evidence for any X-ray emitting central compact object is found. Towards the Leo I and UMa II fields of view, we reveal 116 and 49 X-ray sources, respectively. None of them correlates with the putative central black holes and only one is likely associated with a UMa II local source. The study of the UMi dwarf galaxy found 54 high-energy sources and a possible association with a source at the dwarf spheroidal galaxy centre. We put an upper limit on the luminosity of the central compact object of 4.02x10^33^erg/s. Furthermore, via the correlation with a radio source near the galactic centre, the putative black hole should have a mass of (2.76^+32.00^_-2.54_)x10^6^M_{sun}_ and be radiatively inefficient. This confirms a previous result obtained using Chandra data alone.
We present here the results of a Fourier photometric decomposition of a representative sample of ~100 isolated CIG galaxies (Catalog of Isolated Galaxies) in the morphological range Sb-Sc. This study is an integral part of the AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) project. It complements the photometric analysis presented in our previous paper for the same sample of disc galaxies by allowing a description of the spiral structure morphology. We also estimate dynamical measures like torque strength for bar and spiral, and also the total non-axisymmetric torque by assuming a constant mass-to-light ratio, and explore the interplay between the spiral and bar components of galaxies. Both the length (l_bar_) and the contrast (e.g. A_2b_) of the Fourier bars decrease along the morphological sequence Sb-Sbc-Sc, with bars in earlier types being longer and showing higher contrast. The bars of Sb galaxies are ~ three times longer than the bars in Sc types, consistent with our previous study. We find that the longer bars are not necessarily stronger (as quantified by the torque Q_b_measure), but longer bars show a higher contrast A_2b_, in very good agreement with theoretical predictions. Our data suggest that bar and spiral components are rather independent in the sense that the torque strengths of the two components are not correlated. The total strength Q_g_ is a very reliable tracer of the bar strength measure Q_b_, the two quantities showing a very tight linear correlation. Comparison with a similar sample of disc galaxies (same morphological range) extracted from the OSUBGS (Ohio State University Bright Galaxy Survey) indicates that the isolated CIG/AMIGA galaxies host significantly longer Fourier bars and possibly show a different distribution of spiral torque Q_s_. The Fourier analysis also revealed a potential case of counterwinding spiral structure (KIG652/NGC5768), which deserves further kinematic study. We find that m=2 (i.e. dominating two-armed pattern) is the most common spiral arm multiplicity among the sample of Sb-Sc CIG/AMIGA galaxies (~40 per cent), m=2 and 3 and m=1 and 2 are found in ~28 and ~13 per cent of isolated galaxies, respectively.
The FourStar galaxy evolution survey (ZFOURGE) is a 45 night legacy program with the FourStar near-infrared camera on Magellan and one of the most sensitive surveys to date. ZFOURGE covers a total of 400arcmin^2^ in cosmic fields CDFS, COSMOS and UDS, overlapping the CANDELS fields.
This paper presents HI observations of 165 dwarf galaxy candidates from the Karachentsev catalog of candidates for nearby dwarf galaxies prepared from film copies of POSSII and the ESO/SERC southern extension. Now a total of 601 galaxies from the published Karachentsev catalog have been searched for HI emission. Table 1 lists coordinates and general optical properties while Table 2 presents HI data and some global properties of these galaxies.