Ginevra Trinchieri

The distribution of hot interstellar medium in early-type galaxies (ETGs) bears the imprint of the various astrophysical processes it underwent during its evolution. The X-ray observations of these galaxies have identified various structural features related to active galactic nucleus (AGN) and stellar feedback and environmental effects such as merging and sloshing. In our XMM-Newton Galaxy Atlas (NGA) project, we analyze archival observations of 38 ETGs, utilizing the high sensitivity and large field of view of XMM-Newton to construct spatially resolved 2D spectral maps of the hot gas halos. To illustrate our NGA data products in conjunction with the Chandra Galaxy Atlas, we describe two distinct galaxies, NGC 4636 and NGC 1550, in detail. We discuss their evolutionary history with a particular focus on the asymmetric distribution of metal-enriched, low-entropy gas caused by sloshing and AGN-driven uplift. We will release the NGA data products to a dedicated website, from where users can download them to perform further analyses.

This paper presents an update on women and physics in Italy over the past five years. The numbers of women with physics degrees and the statistics on women with careers in universities or in the main Italian research institutions (National Institute for Nuclear Physics, National Institute of Astrophysics, and National Research Council) are given. Also, results are reported from European projects, such as Transforming Organisational Culture for Gender Equality in Research and Innovation and Gender Equality Network in the European Research Area in which Italy is involved.

We observed the giant elliptical galaxy M 87 during the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Hα+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada French Hawaii Telescope (CFHT). The deep narrow-band image confirmed the presence of a filament of ionised gas extending up to ≃3 kpc in the north-western direction and ≃8 kpc to the southeast, with a couple of plumes of ionised gas, the weakest of which, at ≃18 kpc from the nucleus, was previously unknown. The analysis of deep optical images taken from the NGVS survey confirms that this gas filament is associated with dust seen in absorption which is now detected up to ≃2.4 kpc from the nucleus. We also analysed the physical and kinematical properties of the ionised gas filament using deep IFU MUSE data covering the central 4.8 × 4.8 kpc²of the galaxy. The spectroscopic data confirm a perturbed kinematics of the ionised gas, with differences in velocity of ≃700–800 km s⁻¹on scales of ≲1 kpc. The analysis of 2D diagnostic diagrams and the observed relationship between the shock-sensitive [OI]/Hαline ratio and the velocity dispersion of the gas suggest that the gas is shock-ionised.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

We observed the late-type peculiar galaxy NGC 4424 during the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Hα+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada-French-Hawaii Telescope (CFHT). The presence of a ∼110 kpc (in projected distance) HI tail in the southern direction indicates that this galaxy is undergoing a ram pressure stripping event. The deep narrow-band image revealed a low surface brightness (Σ(Hα) ≃ 4 × 10⁻¹⁸ erg s⁻¹ cm⁻² arcsec⁻²) ionised gas tail ∼10 kpc in length extending from the centre of the galaxy to the north-west, thus in the direction opposite to the HI tail. Chandra and XMM X-rays data do not show a compact source in the nucleus or an extended tail of hot gas, while IFU spectroscopy (MUSE) indicates that the gas is photo-ionised in the inner regions and shock-ionised in the outer parts. Medium-resolution (MUSE) and high-resolution (Fabry-Perot) IFU spectroscopy confirms that the ionised gas is kinematically decoupled from the stellar component and indicates the presence of two kinematically distinct structures in the stellar disc. The analysis of the SED of the galaxy indicates that the activity of star formation was totally quenched in the outer disc ∼250–280 Myr ago, while only reduced by ∼80% in the central regions. All this observational evidence suggests that NGC 4424 is the remnant of an unequal-mass merger that occurred ≲500 Myr ago when the galaxy was already a member of the Virgo cluster, and is now undergoing a ram pressure stripping event that has removed the gas and quenched the activity of star formation in the outer disc. The tail of ionised gas probably results from the outflow produced by a central starburst fed by the collapse of gas induced by the merging episode. This outflow is sufficiently powerful to overcome the ram pressure induced by the intracluster medium on the disc of the galaxy crossing the cluster. This analysis thus suggests that feedback can participate in the quenching process of galaxies in high-density regions.

Context. Probing both star formation history and evolution of distant cluster galaxies is essential to evaluate the effect of dense environment on shaping the galaxy properties we observe today. Aims. We investigate the effect of cluster environment on the processing of the molecular gas in distant cluster galaxies. We study the molecular gas properties of two star-forming galaxies separated by 6 kpc in the projected space and belonging to a galaxy cluster selected from the frac Shallow Cluster Survey, at a redshift z = 1.2, that is,similar to 2 Gyr after the cosmic star formation density peak. This work describes the first CO detection from 1 < z < 1.4 star-forming cluster galaxies with no clear reported evidence of active galactic nuclei. Methods. We exploit observations taken with the NOEMA interferometer at similar to 3 mm to detect CO(2-1) line emission from the two selected galaxies, unresolved by our observations. Results. Based on the CO(2-1) spectrum, we estimate a total molecular gas mass M(H-2) = (2.2(-0.4)(+0.5)) x 10(10) M-circle dot, where fully excited gas is assumed, and a dust mass M-dust < 4.2 x 10(8) M(circle dot )for the two blended sources. The two galaxies have similar stellar masses and H alpha-based star formation rates (SFRs) found in previous work, as well as a large relative velocity of similar to 400 km s(-1) estimated from the CO(2-1) line width. These findings tend to privilege a scenario where both sources contribute to the observed CO(2-1). Using the archival Spitzer MIPS flux at 24 mu m we estimate an SFR (24 mu m) = (24(-8)(+12)) M-circle dot/yr for each of the two galaxies. Assuming that the two sources contribute equally to the observed CO(2-1), our analysis yields a depletion timescale of tau(dep) = (3.9(-1.8)(+1.4)) x 10(8) yr, and a molecular gas to stellar mass ratio of 0.17 +/- 0.13 for each of two sources, separately. We also provide a new, more precise measurement of an unknown weighted mean of the redshifts of the two galaxies, z = 1.163 +/- 0.001. Conclusions. Our results are in overall agreement with those of other distant cluster galaxies and with model predictions for main sequence (MS) field galaxies at similar redshifts. The two target galaxies have molecular gas mass and depletion times that are marginally compatible with, but smaller than those of MS field galaxies, suggesting that the molecular gas has not been sufficiently refueled. We speculate that the cluster environment might have played a role in preventing the refueling via environmental mechanisms such as galaxy harassment, strangulation, ram-pressure, or tidal stripping. Higher-resolution and higher-frequency observations will enable us to spatially resolve the two sources and possibly distinguish between different gas processing mechanisms.

We have analyzed the Chandra archival data of NGC 1132, a well-known fossil group, i.e., a system expected to be old and relaxed long after the giant elliptical galaxy assembly. Instead, the Chandra data reveal that the hot gas morphology is disturbed and asymmetrical, with a cold front following a possible bow shock. We discuss possible origins of the disturbed hot halo, including sloshing by a nearby object, merger, ram pressure by external hotter gas, and nuclear outburst. We consider that the first two mechanisms are likely explanations for the disturbed hot halo, with a slight preference for a minor merger with a low impact parameter because of the match with simulations and previous optical observations. In this case, NGC 1132 may be a rare example of unusual late mergers seen in recent simulations. Regardless of the origin of the disturbed hot halo, the paradigm of the fossil system needs to be reconsidered.