Focus Meeting 4 (FM4) on Planetary nebulae as probes of galactic structure and evolution was held as part of the XXIXth IAU General Assembly, Honolulu, Hawaii, USA, in August 2015. We had 11 invited reviews, 21 contributed talks, and ~ 30 posters. Because of page limitations, we have decided to publish only the invited reviews. In what follows, we attempt to summarize what the reader can expect to find in these proceedings.

Since the first detection of intracluster planetary nebulae in 1996, imaging and spectroscopic surveys identified such stars to trace the radial extent and the kinematics of diffuse light in clusters. This topic of research is tightly linked with the studies of galaxy formation and evolution in dense environment, as the spatial distribution and kinematics of planetary nebulae in the outermost regions of galaxies and in the cluster cores is relevant for setting constraints on cosmological simulations. In this sense, extragalactic planetary nebulae play a very important role in the near-field cosmology, in order to measure the integrated mass as function of radius and the orbital distribution of stars in structures placed in the densest regions of the nearby universe.

Recent studies of planetary nebulae and deep color-magnitude diagrams in M 31 have unveiled some unusual star-formation events beyond its spiral arms into its outer regions extending to 100 kpc in projected distance. In this paper I summarize these observations. I shall also highlight some special interpretive surprises suggested by observations of PNe related to their O/H abundances, ages, and the luminosities on PNe well beyond the inner disk.

The bright-end cutoff of the [O III] λ5007 planetary nebula luminosity function (PNLF) is insensitive to population age and metallicity, making it an excellent extragalactic standard candle. We review our knowledge of the function and discuss the challenges related to modeling it. We show that, while there has been a great deal of progress in understanding the nuances of its shape, there is still no solid theory which explains the luminosity of the PNLF cutoff in old stellar populations. This is an extremely serious problem, as it affects a myriad of astrophysical issues, from the determination of the stellar masses of galaxies to our understanding of alternative channels of stellar evolution.

The kinematics and dynamical properties of galaxy stellar halos are difficult to measure, given the faint surface brightness that characterizes these regions. Gas-rich systems such as spiral galaxies can be probed using the radio Hi emission. Early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary Nebulae (PNe) can be easily detected far out in the halo thanks to their bright [O iii] emission at 5007 Å. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on few tens of galaxies where the kinematics of the stellar halos are measured. I will discuss the most important results: (a) the relation of the stellar surface brightness and the PNe number density; (b) the velocity and velocity dispersion two-dimensional fields; (c) the radial profiles of angular momentum; and (d) the relation between the derived kinematics physical properties of the host galaxies.

The stellar phase of Thermally-Pulsating Asymptotic giant branch is the last major evolutionary stage of intermediate-mass stars which afterwards evolve into planetary nebulae. The TP-AGB phase is affected by mass-loss and instabilities which notoriously make its theoretical modelling uncertain. This review focuses on the effects such modelling has on stellar population models for galaxies, with particular focus on the high-z Universe where galaxies are young and contain a large number of short-living TP-AGB stars. I shall present the models, discuss how different prescriptions for the treatment of the TP-AGB affect the theoretical integrated spectral energy distribution and how these compare to galaxy data, and discuss implications for the PN nebulae luminosity function stemming from the various assumptions. Finally I shall discuss the inclusion of hot evolved stars on stellar population models and how they compare to data for old galaxies at our present time.

The diversity of collimated outflows in post-asymptotic-giant-branch stars and their planetary nebula progeny are often explained by a combination of close binary interactions and accretion. The viability of such scenarios can be tested by comparing kinematic outflow data to determine minimum accretion rates necessary to power observed outflows. While many binary channels have been ruled out with this technique, common envelope interactions can accommodate the current observational constraints, are potentially common, lead to a diverse array of planetary-nebula shapes, and naturally produce period gaps for companions to white dwarfs.

This paper is an introduction to Focus Meeting 5 held at the IAU's General Assembly held in Honolulu in August 2015. It describes the rationale for the meeting, and summarizes the introductory talk to FM5, which contained a description of the Planck data products released by ESA and the Planck Collaboration in the first half of 2015.

An essential quantity required to understand the physics of the early Universe is the primordial scalar potential and its statistics. We present an inexpensive all-sky reconstruction of the potential from CMB temperature data as well as an extension including polarization data. Once explicitly having the potential, its statistics and underlying physics can be directly obtained avoiding expensive CMB analyses.

The Planck satellite has mapped the polarized microwave sky (from 30 GHz to 353 GHz) with unprecedented sensitivity and angular resolution. This wealth of data yields the first complete map of polarized thermal emission from dust in our own Galaxy, shedding new light on the formation of dense cold structures within which new stars and planetary systems are born, under the combined effects of gravity, turbulence and magnetic fields. We present a statistical analysis of this polarized emission from nearby molecular clouds, with an emphasis on the evolution of the maximum polarization fraction observed as a function of column density, and on the anti-correlation between the polarization fraction and the local dispersion of polarization angles. To interpret this data, numerical simulations of anisotropic MHD turbulence underline the essential role played by the topology of the interstellar magnetic field, in particular its large-scale component. Indeed, the polarization of dust thermal emission at the scales observed by Planck is essentially related to the geometry of the magnetic field. Polarization fractions anti-correlate with column densities, which may be due to a succession of variously polarized structures on the line of sight. They also anti-correlate with the local dispersion of polarization angles. These features are well reproduced by MHD simulations of the diffuse ISM, with comparable correlation coefficients. As an extension to this work published in Planck Intermediate Results XX (A&A, 576, 105, 2015), the statistical properties of the random component of the interstellar magnetic field are explored using a toy model of the turbulent magnetized ISM based on fractional Brownian motion (fBm) fields. A least-squares analysis to retrieve the statistical properties of the interstellar magnetic field from Planck observations is pursued. Application of this method on the toy model shows good promise, and we are currently working towards its application on Planck data.

Planck scanned the entire sky every six months at nine frequencies bands from 28 to 857 GHz with enough sensitivity to detect over a thousand radio sources. It thus provided measurements of the mm and sub-mm spectra of these sources in a regular cadence, even at wavelengths hard to observe from the ground. Polarization measurements (or upper limits) are provided for brighter sources at 28-353 GHz. Finally, Planck is calibrated to <1% accuracy in most of its frequency bands. I briefly introduce the valuable data set Planck provides on extragalactic sources, then describe some of the scientific conclusions drawn from the Planck measurements.

The QUIJOTE (Q-U-I JOint Tenerife) Experiment† (Rubiño-Martín et al. 2010)) is observing the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range of 10-40 GHz. This experiment is going to provide valuable information about the polarization properties of synchrotron and anomalous microwave emission at these frequencies. It consists of two telescopes and three instruments located at the the Teide Observatory (2400 m) in Tenerife, Canary Islands, Spain. This project has two phases: Phase I, the first telescope (QT1) and a multi-frequency instrument (MFI) are in operations since November 2012 observing between 10 and 20 GHz. A second instrument (TGI) with 31 polarimeters working at 30 GHz is expected to start operations in Autumn 2015 and will be devoted to primordial B-mode science. This instrument will include a fixed polariser and 90 and 180 phase switches to generate four polarization states to minimize the different systematics in the receiver; Phase II, a second QUIJOTE telescope (QT2), already in operation, and a third instrument (FGI) with 40 polarimeters working at 41 GHz, safely below the 60-GHz oxygen absorption band, will significantly increment the sensitivity of the QUIJOTE project to detect the r parameter (tensor-to-scalar ratio). The reason for this is not only the significant reduction of noise due to the number of polarimeters that will incorporate but also the lower synchrotron signal from our galaxy expected at these higher frequencies.

The maps obtained with the multi-frequency instrument (10-20 GHz), in combination with data from other experiments like Planck and the VLA, will be used to clean the diffuse and compact foreground emission at 30 and 40 GHz, the cosmological channels. After three years of effective observations we expect to reach the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05. At the moment we have completed the Wide Survey with the multi-frequency instrument, covering 20.000 square degrees of the Northern hemisphere. In addition, we have deep integrations of our main calibrators Taurus A, Cassiopea A, Jupiter and of the Perseus molecular complex.

In particular, the first results obtained from the measurement of the intensity and polarisation of the anomalous microwave emission inthis region, G159.6-18.5, have been recently published in Génova-Santos et al. 2015). This article presents the most precise spectrum of the anomalous microwave emission (AME) measured to date in an individual region, with 13 independent data points between 10 and 50 GHz being dominated by this emission. The four QUIJOTE data points provide the first independent confirmation of the downturn of the AME spectrum at low frequencies, initially unveiled by the COSMOlogical Structures On Medium Angular Scales (COSMOSOMAS) experiment in this region. We also have observed several regions of interest for our science program where we plan to study the compact and diffuse polarized emission.

We present new measurements of the power spectra of the cosmic infrared background (CIB) anisotropies using the Planck 2015 full-mission HFI data at 353, 545, and 857 GHz over 20 000 square degrees. Unlike previous Planck measurements of the CIB power spectra, we do not rely on external HI data to remove Galactic dust emission from the Planck maps. Instead, we model the Galactic emission at the level of the power spectra, using templates constructed directly from the Planck data by exploiting the statistical isotropy of all extragalactic emission components. This allows us to work at the full resolution of Planck over large sky areas. We construct a likelihood based on the measured spectra (for multipoles 50 ≤ ℓ ≤ 2500) using analytic covariance matrices that account for masking and the realistic instrumental noise properties. The results of an MCMC exploration of this likelihood are presented, based on simple parameterised models of the CIB power that arises from clustering of infrared galaxies. We explore simultaneously the parameters describing the clustered power, the Poisson power levels, and the amplitudes of the Galactic power spectrum templates across the six frequency (cross-)spectra. The best-fit model provides a good fit to all spectra. As an example, Fig. 1 compares the measured auto spectra at 353, 545, and 857 GHz over 40% of the sky to the power in the best-fit model. We find that the power in the CIB anisotropies from galaxy clustering is roughly equal to the Poisson power at multipoles ℓ =2000 (the clustered power dominates on larger scales), and that our dust-cleaned CIB spectra are in good agreement with previous Planck and Herschel measurements. A key feature of our analysis is that it allows one to make many internal consistency tests. We show that our results are stable to data selection and choice of survey area, demonstrating both our ability to remove Galactic dust power to high accuracy and the statistical isotropy of the CIB signal.

We investigate the clustering of clusters detected by Planck via the Sunyaev-Zeldovich (SZ) effect. The bias (the offset of the clustering relative to what is expected for dark matter) is then used to estimate the average mass of clusters in the sample, using mass-bias relations found in simulations. We also compare the clustering of Planck clusters with those detected in the Sloan Digital Sky Survey (SDSS) using the GMBCG method. Our results indicate that Planck clusters have a higher average mass than that inferred from their SZ signatures.

We present a set of time dependent chemical evolution models (based on the UMIST† astrochemistry 2012 code, McElroy et al. (2013) for a range of initial physical cloud parameters: 10 K < T < 20 K; 103 cm−3 < n(H2) < 5 ⋅ 104 cm−3; 1 < AV < 10 and with estimated values of scaled interstellar ultraviolet radiation field. We compare our chemical model results with the relative abundances of: CO, CH, OH, HCO+, HCN, HNC, NH3, N2H+ and H2CO molecules. We find significant time dependent variations of the chemical ratios of: X(NH3/H2); X(HCO+/H2) and X(HCO+/NH3). The input physical conditions were taken from Fehér O. et al. (2015) at 16 positions along the TMC-1 dark cloud. The NH3 and HCO+ relative densities based on the observations of Fehér O. et al. (2015) help to find the “chemical age” of the given position in the evolution curves.

By examining Herschel images in the HerMES & H-ATLAS surveys at the position of Planck Catalog of Compact Source sources we are able to determine the nature of the Planck sources. Most are simply nearby, known, dusty galaxies, while others are foreground galactic ‘cirrus’ dust. About 11% of sources, though, appear to be groups or clumps of fainter Herschel objects. Followup of a number of these indicates that they are galaxy clusters or protoclusters at z ~1-3 that contain a number of galaxies undergoing contemporaneous massive starbursts. These sources present challenges for current galaxy & cluster formation/evolution models.

The Magneticum Pathfinder (www.magneticum.org) cosmological, hydro-dynamical simulation (896h-1Mpc)3 follows in detail the thermal and chemical evolution of the ICM as well as the evolution of SMBHs and their associated feedback processes. We demonstrate that assuming cosmological parameters inferred from the CMB, the thermal SZ power spectrum as observed by PLANCK is well matched by the deep light-cones constructed from these cosmological simulations. The thermal SZ prediction from the full SZ maps are significantly exceeding previous templates at large l (e.g., l > 1000) and therefore predict a significantly larger contribution to the signal at l = 3000 compared to previous findings. The excess of positive values within the probability distribution of the thermal SZ signal within the simulated light-cone agrees with the one seen by PLANCK. This excess signal follows a power law shape with an index of roughly -3.2. The bulk of the thermal SZ signal originates from clusters and groups which form between z = 0 and z ≈ 2 where at high redshift (z > 1) significant part of the signal originates from proto-cluster regions, which are not yet virialized. The simulation predicts a mean fluctuating Compton Y value of 1.18 × 10-6, with a remaining contribution of almost 5 ×10-7 when removing contribution from halos above a virial mass of 1013 M⊙/h.

Galactic cold clumps have been identified from the Planck data (Planck Collaboration, 2011a, 2011b, 2015) as 10 342 cold (7 - 19 K) sources that stand out against a warmer environment, with the Early Cold Cores as a subsample of 915 most reliable detections. There is CO emission associated with the Planck Cold Clumps (PCCs), which has been observed with ground-based radio telescopes at higher resolution (Wu et al. 2012, Liu et al. 2014). A subset of PCCs have also been observed with Herschel at higher resolution (Juvela et al. 2012).

A southern sub-sample of the PCCs has been observed with the Mopra 22-m telescope to study the molecular gas. The Mopra telescope has 3-mm, 7-mm and 12-mm bands, with broadband correlator configuration 8-GHz wide with 0.27-MHz channels, or multiple zoom bands 137-MHz wide with 33-KHz channels, within the 8 GHz.

During the 2013 southern winter season we observed 10 clumps. This included observations in the 3-mm band of 12CO, 13CO and C18O and lines around 89 GHz (e.g. HCN, HCO+ and HNC), in the 7-mm band (e.g. CS) and in the 12-mm band (e.g. NH3). These observations were heterogenous, with sources selected by LST in gaps between observations of other projects, and band chosen by weather (i.e. in conditions unsuitable for higher frequencies, lower frequency bands were observed). During the 2014 season we observed 34 positions in 22 clumps, with zoom mode observations of lines around 89 GHz. This was a more well-defined sample of sources.

The mapping of the CO lines shows good spatial correlation of the CO with the dust column density The CO isotoplogues show high optical depth in 12CO and 13CO. The lines of HCN, HCO+ and HNC are weak, but detected in many of the 2014 sample. We are modelling the line results to determine column densities, excitation temperatures and abundances, using tools such as radex (van der Tak et al. 2007).

The Planck Collaboration has produced catalogues of radio and sub-millimeter compact sources at the nine Planck frequencies in total intensity and polarization. In particular, the 2015 Second Planck Catalogue of Compact Sources (PCCS2) contains over 45.000 sources detected in the Planck full mission maps. Since the Planck instruments have polarization capabilities in seven of its nine detectors, we were able to measure the polarized flux density of over 600 sources between 30 and 353 GHz. But we are searching not only for compact sources in single frequency maps, and we take advantage of the large frequency coverage of Planck to search for objects with specific emission laws. This is the case of the SZ catalogue of cluster of galaxies (PSZ2), that lists 1653 clusters, 1203 of which are confirmed clusters with clear associations in external data-sets, and the Galactic cold clump catalogue (PGCC) with 13188 objects. The Planck Collaboration has also published a list of high-redshift source candidates (see the report by Ludovic Montier here). These objects are rare bright sub-millimeter sources with an spectral energy distribution peaking between 353 and 857 GHz, and have been detected combining Planck and IRAS data. The colours of most of these objects are consistent with redshifts z>2, a fraction of which could be lensed objects with redshifts between 2 and 4.

But new catalogues are foreseen. A multi-frequency compact source catalogue is being produced selecting sources at radio frequencies and studying them across all Planck bands. Multi-frequency catalogues can be difficult to produce in experiments like Planck that have a large frequency coverage and very different resolutions across bands. In some cases, a source can be very bright across the whole Planck frequency range and it is easy to do the associations across channels. However, it frequent to find unrelated sub-millimeter sources within the half-degree beam of the 30 GHz low frequency detector, and the association work must be done with great care. For this purpose, we are combining a multi-frequency detection procedure with a principal component analysis to produce the catalogue. In addition, for those sources where a clear identification can be made, we will attempt to include flux density information from Herschel and other experiments, in particular for those blazars that are bright in radio, sub-mm and even in gamma-ray frequencies, as seen by Fermi. Moreover, Planck has made available to the community the single survey frequency maps that allow astronomers to study the long-term variability of their favourite sources. New functionalities will be also added to the Planck Legacy Archive†, for example a timeline-cutting tool that will allow one to produce full-sky maps from the Planck timelines for specific periods of time allowing for short-term variability studies of compact sources (e.g., flares). The unique frequency coverage of Planck make these catalogues very valuable for other experiments using the Planck compact source catalogues. For example, experiments like QUIJOTE use Planck selected sources to study the impact of polarized radio source emission on their cosmological fields and other CMB experiments will use Planck polarized compact source information for calibration.

The sky is full of variable and transient sources on all time scales, from milliseconds to decades. Planck's regular scanning strategy makes it an ideal instrument to search for variable sky signals in the millimetre and submillimetre regime, on time scales from hours to several years. A precondition is that instrumental noise and systematic effects, caused in particular by non-symmetric beam shapes, are properly removed. We present a method to perform a full sky blind search for variable and transient objects at all Planck frequencies.