Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLuminosity Functions and Host-to-Host Scatter of Dwarf Satellite Systems in the Local Volume
81
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Low-mass satellites around Milky Way (MW)-like galaxies are important probes of small scale structure and galaxy formation. However, confirmation of satellite candidates with distance measurements remains a key barrier to fast progress in the Local Volume (LV). We measure the surface brightness fluctuation (SBF) distances to recently cataloged candidate dwarf satellites around 10 massive hosts within $D<12$ Mpc to confirm association. The satellite systems of these hosts are complete and mostly cleaned of contaminants down to $M_g{sim}-9$ to $-10$, within the area of the search footprints. Joining this sample with hosts surveyed to comparable or better completeness in the literature, we explore how well cosmological simulations combined with common stellar to halo mass relations (SHMR) match observed satellite luminosity functions in the classical satellite luminosity regime. Adopting a SHMR that matches hydrodynamic simulations, the predicted overall satellite abundance agrees well with the observations. The MW is remarkably typical in its luminosity function amongst LV hosts. Contrary to recent results, we find that the host-to-host scatter predicted by the model is in close agreement with the scatter between the observed systems, once the different masses of the observed systems are taken into account. However, we find significant evidence that the observed systems have more bright and fewer faint satellites than the SHMR model predicts, necessitating a higher normalization of the SHMR around halo masses of $10^{11}$ msun than present in common SHMRs. These results demonstrate the utility of nearby satellite systems in inferring the galaxy-subhalo connection in the low-mass regime.
rate research
Read More
The radial spatial distribution of low-mass satellites around a Milky Way (MW)-like host is an important benchmark for simulations of small-scale structure. The distribution is sensitive to the disruption of subhalos by the central disk and can indicate whether the disruption observed in simulations of MW analogs is artificial (i.e., numeric) or physical in origin. We consider a sample of 12 well-surveyed satellite systems of MW-like hosts in the Local Volume that are complete to $M_V<-9$ and within 150 projected kpc. We investigate the radial distribution of satellites and compare with $Lambda$CDM cosmological simulations, including big-box cosmological simulations and high resolution zoom in simulations of MW sized halos. We find that the observed satellites are significantly more centrally concentrated than the simulated systems. Several of the observed hosts, including the MW, are $sim2sigma$ outliers relative to the simulated hosts in being too concentrated, while none of the observed hosts are less centrally concentrated than the simulations. This result is robust to different ways of measuring the radial concentration. We find that this discrepancy is more significant for bright, $M_V<-12$ satellites, suggestive that this is not the result of observational incompleteness. We argue that the discrepancy is possibly due to artificial disruption in the simulations, but, if so, this has important ramifications for what stellar to halo mass relation is allowed in the low-mass regime by the observed abundance of satellites.
We have obtained deep Hubble Space Telescope (HST) imaging of 19 dwarf galaxy candidates in the vicinity of M101. Advanced Camera for Surveys HST photometry for 2 of these objects showed resolved stellar populations and Tip of the Red Giant Branch derived distances consistent with M101 group membership. The other 17 were found to have no resolved stellar populations, meaning they are background low surface brightness (LSB) galaxies. It is notable that many LSB objects which had previously been assumed to be M101 group members based on projection have been shown to be background objects, indicating the need for future diffuse dwarf surveys to be careful in drawing conclusions about group membership without robust distance estimates. In this work we update the satellite luminosity function of M101 based on the presence of these new objects down to M_V=-8.2. M101 is a sparsely populated system with only 9 satellites down to M_V~-8, as compared to 26 for M31 and 24.5pm7.7 for the median local Milky Way (MW)-mass host. This makes M101 the sparsest group probed to this depth, though M94 is even sparser to the depth it has been examined (M_V=-9.1). M101 and M94 share several properties that mark them as unusual compared to the other local MW-mass galaxies examined: they have a sparse satellite population but also have high star forming fractions among these satellites; such properties are also found in the galaxies examined as part of the SAGA survey. We suggest that these properties appear to be tied to the galactic environment, with more isolated galaxies showing sparse satellite populations which are more likely to have had recent star formation, while those in dense environments have more satellites which tend to have no recent star formation. Overall our results show a level of halo-to-halo scatter between galaxies of similar mass that is larger than is predicted in the LambdaCDM model.
We present the results of an extensive search for dwarf satellite galaxies around 10 primary host galaxies in the Local Volume (D$<$12 Mpc) using archival CFHT/MegaCam imaging data. The hosts span a wide range in properties, with stellar masses ranging from that of the LMC to ${sim}3$ times that of the Milky Way (MW). The surveyed hosts are: NGC 1023, NGC 1156, NGC 2903, NGC 4258, NGC 4565, NGC 4631, NGC 5023, M51, M64, and M104. We detect satellite candidates using a consistent semi-automated detection algorithm that is optimized for the detection of low surface brightness objects. Depending on the host, our completeness limit is $M_g{sim}-8$ to $-10$ (assuming the distance of the host). We detect objects with surface brightness down to $mu_{0,g}{sim}26$ mag arcsec$^{-2}$ at $gtrsim90%$ completeness. The survey areas of the six best-surveyed hosts cover most of the inner projected $R<150$ kpc area, which roughly doubles the number of MW-mass hosts surveyed at this level of area and luminosity completeness. The number of detected candidates range from 1 around M64 to 33 around NGC 4258. In total, 153 candidates are found, of which 93 are new. While we defer an analysis of the satellite luminosity functions of the hosts until distance information is available for the candidates, we do show that the candidates are primarily red, spheroid systems with properties roughly consistent with known satellites in the Local Group.
The total luminosity of satellite galaxies around a central galaxy, L$_{sat}$, is a powerful metric for probing dark matter halos. In this paper we use data from the Sloan Digital Sky Survey and DESI Legacy Imaging Surveys to explore the relationship between L$_{sat}$ and various observable galaxy properties for a sample of 117,966 central galaxies out to $z = 0.15$. At fixed stellar mass, every galaxy property we explore shows a correlation with L$_{sat}$. This implies that dark matter halos play a possibly significant role in determining these secondary galaxy properties. We quantify these correlations by computing the mutual information between L$_{sat}$ and secondary properties and explore how this mutual information varies as a function of stellar mass and when separating the sample into star-forming and quiescent central galaxies. We find that absolute r-band magnitude correlates more strongly with L$_{sat}$ than stellar mass across all galaxy populations; and that effective radius, velocity dispersion, and Sersic index do so as well for star-forming and quiescent galaxies. L$_{sat}$ is sensitive to both the mass of the host halo as well as the halo formation history, with younger halos having higher L$_{sat}$. L$_{sat}$ by itself cannot distinguish between these two effects, but measurements of galaxy large-scale environment can break this degeneracy. For star-forming central galaxies, we find that r$_{rm eff}$, $sigma_v$, and Sersic index all correlate with large-scale density, implying that these halo age plays a role in determining these properties. For quiescent galaxies, we find that all secondary properties are independent of environment, implying that correlations with L$_{sat}$ are driven only by halo mass. These results are a significant step forward in quantifying the full extent of the galaxy-halo connection, and present a new test of galaxy formation models.
We have investigated effects of dust attenuation on quasar luminosity functions using a semi-analytic galaxy formation model combined with a large cosmological N-body simulation. We estimate the dust attenuation of quasars self-consistently with that of galaxies by considering the dust in their host bulges. We find that the luminosity of the bright quasars is strongly dimmed by the dust attenuation, about 2 mag in the B-band. Assuming the empirical bolometric corrections for active galactic nuclei (AGNs) by Marconi et al., we find that this dust attenuation is too strong to explain the B-band and X-ray quasar luminosity functions simultaneously. We consider two possible mechanisms that weaken the dust attenuation. As such a mechanism, we introduce a time delay for AGN activity, that is, gas fueling to a central black hole starts some time after the beginning of the starburst induced by a major merger. The other is the anisotropy in the dust distribution. We find that in order to make the dust attenuation of the quasars negligible, either the gas accretion into the black holes has to be delayed at least three times the dynamical timescale of their host bulges or the dust covering factor is as small as 0.1.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
