The survey of planetary nebulae in Andromeda (M 31)

Bhattacharya, Souradeep; Arnaboldi, M.; Caldwell, Nelson; Gerhard, Ortwin; Blaña, M.; McConnachie, Alan W.; Hartke, Johanna; Guhathakurta, Puragra; Pulsoni, C.; Freeman, K. C.

doi:10.1051/0004-6361/201935898

Cited by 33 publications

(46 citation statements)

References 47 publications

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“…The M2M model of the Andromeda Galaxy from Blaña Díaz et al Hence, the model's mean scale height of 0.72 kpc is comparable to the h z = 0.86 ± 0.01 kpc, which can be inferred from the PHAT survey (Dalcanton et al 2015, see also Bhattacharya et al 2019). Blaña Díaz et al (2018 also included a dust model to screen material behind the disc plane of M 31.…”

Section: M31 Dynamical Model and Parameters Used In Stellar Populatiomentioning

confidence: 65%

“…Differently from the models, the metallicity distribution in M 31 keeps flaring with growing distance from the centre. The origin of this flare could be related to the heating of the disk caused by the merger inferred to have occurred ∼3 Gyr ago (Hammer et al 2018;Bhattacharya et al 2019). On the other hand, the cosmological zoom-in model of Rahimi et al (2014) also exhibits a positive radial metallicity gradient at large heights.…”

Section: Origins Of the Spatial Trendsmentioning

confidence: 98%

“…Clearly, the flaring of the [Z/H] distribution further out is unrelated to the B/P bulge. It is possible that the metal-rich disc of M 31 was thickened due to the recent merger inferred from the age-velocity dispersion relation of the disc (Bhattacharya et al 2019). In the end-on view (the right panel of Fig.…”

Section: Metallicitymentioning

confidence: 99%

“…Further work is needed to understand the influence of the purported recent merger on M 31 (Hammer et al 2018; A131, page 14 of 20 Bhattacharya et al 2019), and whether it deposited enough material in the bar region to significantly change the mean stellar population parameters there. Alternatively, the enhancement along the bar may be caused by the so-called kinematic fractionation effect (Debattista et al 2017;Fragkoudi et al 2017), by which the population that is colder prior to the bar formation would become more strongly aligned with the bar afterwards.…”

Section: Origins Of the Spatial Trendsmentioning

confidence: 99%

“…Opitsch et al (2018) provide a more extensive account of the evidence for the barred nature of M 31. Several lines of evidence, such as the presence of the giant stellar stream (GSS, e.g., Sadoun et al 2014;Hammer et al 2018) and several other substructures, the recent burst of star formation (Williams et al 2015), and the stellar age-velocity dispersion relation in the disc (Bhattacharya et al 2019), point to a recent (∼3 Gyr ago) merger with a mass ratio approximately 1:5, which would likely also have left an impact on the distribution of the stellar populations in the inner regions of M 31.…”

Section: Introductionmentioning

confidence: 99%

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Unravelling stellar populations in the Andromeda Galaxy

Gajda

Gerhard

Blaña

et al. 2021

A&A

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To understand the history and formation mechanisms of galaxies, it is crucial to determine their current multidimensional structure. In this work, we focus on the properties that characterise stellar populations, such as metallicity and [α/Fe] enhancement. We devised a new technique to recover the distribution of these parameters using spatially resolved, line-of-sight averaged data. Our chemodynamical method is based on the made-to-measure framework and results in an N-body model for the abundance distribution. Following a test on a mock data set we found that the radial and azimuthal profiles were well-recovered, however, only the overall shape of the vertical profile matches the true profile. We applied our procedure to spatially resolved maps of mean [Z/H] and [α/Fe] for the Andromeda Galaxy, using an earlier barred dynamical model of M 31. We find that the metallicity is enhanced along the bar, with a possible maxima at the ansae. In the edge-on view, the [Z/H] distribution has an X shape due to the boxy/peanut bulge; the average vertical metallicity gradient is equal to −0.133 ± 0.006 dex kpc−1. We identify a metallicity-enhanced ring around the bar, which also has relatively lower [α/Fe]. The highest [α/Fe] is found in the centre, due to the classical bulge. Away from the centre, the α-overabundance in the bar region increases with height, which could be an indication of a thick disc. We argue that the galaxy assembly resulted in a sharp peak of metallicity in the central few hundred parsecs and a more gentle negative gradient in the remaining disc, but no [α/Fe] gradient. The formation of the bar leads to the re-arrangement of the [Z/H] distribution, causing a flat gradient along the bar. Subsequent star formation close to the bar ends may have produced the metallicity enhancements at the ansae and the [Z/H] enhanced lower-α ring.

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Section: M31 Dynamical Model and Parameters Used In Stellar Populatiomentioning

confidence: 65%

Section: Origins Of the Spatial Trendsmentioning

confidence: 98%

Section: Metallicitymentioning

confidence: 99%

Section: Origins Of the Spatial Trendsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unravelling stellar populations in the Andromeda Galaxy

Gajda

Gerhard

Blaña

et al. 2021

A&A

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Fornax 3D project: Automated detection of planetary nebulae in the centres of early-type galaxies and first results

Spriggs

Sarzi

Napiwotzki

et al. 2020

A&A

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Extragalactic planetary nebulae (PNe) are detectable through relatively strong nebulous [O III] emission and act as direct probes into the local stellar population. Because they have an apparently universal invariant magnitude cut-off, PNe are also considered to be a remarkable standard candle for distance estimation. Through detecting PNe within the galaxies, we aim to connect the relative abundances of PNe to the properties of their host galaxy stellar population. By removing the stellar background components from FCC 167 and FCC 219, we aim to produce PN luminosity functions (PNLF) of these galaxies, and thereby also estimate the distance modulus to these two systems. Finally, we test the reliability and robustness of our novel detection and analysis method. It detects unresolved point sources by their [O III] 5007 Å emission within regions that have previously been unexplored. We model the [O III] emissions in the spatial and spectral dimensions together, as afforded to us by the Multi Unit Spectroscopic Explorer, and we draw on data gathered as part of the Fornax3D survey. For each source, we inspect the properties of the nebular emission lines to remove other sources that might hinder the safe construction of the PNLF, such as supernova remnants and H II regions. As a further step, we characterise any potential limitations and draw conclusions about the reliability of our modelling approach through a set of simulations. By applying this novel detection and modelling approach to integral field unit observations, we report for the distance estimates and luminosity-specific PNe frequency values for the two galaxies. Furthermore, we include an overview of source contamination, galaxy differences, and possible effects on the PNe populations in the dense stellar environments.

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The survey of planetary nebulae in Andromeda (M 31)

Bhattacharya

Arnaboldi

Gerhard

et al. 2021

A&A

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Context. The Andromeda (M 31) galaxy displays several substructures in its inner halo. Different simulations associate their origin with either a single relatively massive merger, or with a larger number of distinct, less massive accretions. Aims. The origin of these substructures as remnants of accreted satellites or perturbations of the pre-existing disc would be encoded in the properties of their stellar populations (SPs). The metallicity and star formation history of these distinct populations leave traces on their deep [O III] 5007 Å planetary nebulae luminosity function (PNLF). By characterizing the morphology of the PNLFs, we constrain their origin. Methods. From our 54 sq. deg. deep narrow-band [O III] survey of M 31, we identify planetary nebulae in six major inner-halo substructures: the Giant Stream, North East Shelf, G1 Clump, Northern Clump, Western Shelf, and Stream D. We obtain their PNLFs and those in two disc annuli, with galactocentric radii of RGC = 10–20 kpc and RGC = 20–30 kpc. We measure PNLF parameters from cumulative fits and statistically compare the PNLFs in each substructure and disc annulus. We link these deep PNLF parameters and those for the Large Magellanic Cloud (LMC) to published metallicities and resolved stellar population-age measurements for their parent SPs. Results. The absolute magnitudes (M*) of the PNLF bright cut-off for these sub-populations span a significant magnitude range, despite being located at the same distance and having a similar line-of-sight extinction. The M* values of the Giant Stream, W Shelf, and Stream D PNLFs are fainter than those predicted by PN evolution models by 0.6, 0.8, and 1.5 mag, respectively, assuming the measured metallicity of the parent stellar populations. The faint-end slope of the PNLF increases linearly with decreasing fraction of stellar mass younger than 5 Gyr across the M 31 regions and the LMC. From their PNLFs, the Giant Stream and NE Shelf are consistent with being stellar debris from an infalling satellite, while the G1 Clump appears to be linked with the pre-merger disc with an additional contribution from younger stars. Conclusions. The SPs of the substructures are consistent with those predicted by simulations of a single fairly massive merger event that took place 2–3 Gyr ago in M31. Stream D has an unrelated, distinct origin. Furthermore, this study provides independent evidence that the faint-end of the PNLF is preferentially populated by planetary nebulae evolved from older stars.

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The survey of planetary nebulae in Andromeda (M 31)

Cited by 33 publications

References 47 publications

Unravelling stellar populations in the Andromeda Galaxy

Unravelling stellar populations in the Andromeda Galaxy

Fornax 3D project: Automated detection of planetary nebulae in the centres of early-type galaxies and first results

The survey of planetary nebulae in Andromeda (M 31)

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