DOLoRes@TNG contributes to the dynamical analysis of PSZ2 G282.28+49.94, a recently discovered analogue of the famous "Bullet Cluster"

A new study based on Chandra and TNG data shades light on the distant galaxy cluster PSZ2 G282.28+49.94. Discovered at microwave wavelengths in the Planck all-sky survey, this object attracted the interest of astronomers due to the cometary-like shape of its intracluster medium (ICM), as inferred from X-ray data (see Fig. 1). The Chandra data allowed the characterization of the thermodynamical properties of the ICM, while the spectroscopic data taken with DOLoRes@TNG were crucial to study the spatial and velocity distributions of cluster member galaxies.

In particular, PSZ2 G282.28+49.94 was observed in April 2021 with DOLoRes in multi-object spectroscopic (MOS) mode. "Despite the considerable redshift of the cluster (z~0.6), DOLoRes was able to take good quality spectra of more than 70 galaxies with 2 MOS masks, a remarkable achievement for a 3.6m-class telescope like the TNG", explains Walter Boschin, one of the authors of the study.

The structure of this cluster is quite complex, with an elongated core region containing the two brightest cluster galaxies and one dense group to the south-east. Since there is no velocity difference between the core and the south-east group, the cluster is probably affected by a merging event along the plane of the sky. Comparing the distribution of the ICM and of member galaxies, the data show a large offset of 350 kpc between the position of the hot gas and the galaxy components, one of the largest observed so far. This configuration is similar to the famous "Bullet Cluster" (1E0657-56; see Clowe et al. 2004, ApJ, 604, 596), where the offset between the collisional (ICM) and acollisional (galaxies, dark matter) components of the cluster was observed for the first time and is often considered as a smoking gun for the presence of dark matter itself, since it ruled out alternative models of modified gravity (Clowe et al. 2006, ApJ, 648, L109).

The similarity with 1E0657-56 led the authors to dub PSZ2 G282.28+49.94 the "Planck Bullet", and represents an ideal situation to provide astrophysical constraints to the self-interaction cross-section (σ/m) of dark matter particles.

Further information in the paper I. Bartalucci, M. Rossetti, W. Boschin, et al. 2024, A&A, 689, A324 (see https://ui.adsabs.harvard.edu/abs/2024A%26A...689A.324B/abstract)

Fig. 1. Trichromy of the "Planck Bullet" (filters g, r and i) obtained with DOLoRes@TNG. The white contours are the contour levels of the X-ray emission of the cluster as inferred from Chandra data (FOV~ 5.1x4.4 arcmin).

Fundación Galileo Galilei - INAF Telescopio Nazionale Galileo 28°45'14.4N 17°53'20.6W 2387.2m A.S.L.
Home General Info News Telescope & Instruments Observing Time Allocations & Schedules Publications Seminars Weather Webcam Outreach Gallery Links	DOLoRes@TNG contributes to the dynamical analysis of PSZ2 G282.28+49.94, a recently discovered analogue of the famous "Bullet Cluster" A new study based on Chandra and TNG data shades light on the distant galaxy cluster PSZ2 G282.28+49.94. Discovered at microwave wavelengths in the Planck all-sky survey, this object attracted the interest of astronomers due to the cometary-like shape of its intracluster medium (ICM), as inferred from X-ray data (see Fig. 1). The Chandra data allowed the characterization of the thermodynamical properties of the ICM, while the spectroscopic data taken with DOLoRes@TNG were crucial to study the spatial and velocity distributions of cluster member galaxies. In particular, PSZ2 G282.28+49.94 was observed in April 2021 with DOLoRes in multi-object spectroscopic (MOS) mode. "Despite the considerable redshift of the cluster (z~0.6), DOLoRes was able to take good quality spectra of more than 70 galaxies with 2 MOS masks, a remarkable achievement for a 3.6m-class telescope like the TNG", explains Walter Boschin, one of the authors of the study. The structure of this cluster is quite complex, with an elongated core region containing the two brightest cluster galaxies and one dense group to the south-east. Since there is no velocity difference between the core and the south-east group, the cluster is probably affected by a merging event along the plane of the sky. Comparing the distribution of the ICM and of member galaxies, the data show a large offset of 350 kpc between the position of the hot gas and the galaxy components, one of the largest observed so far. This configuration is similar to the famous "Bullet Cluster" (1E0657-56; see Clowe et al. 2004, ApJ, 604, 596), where the offset between the collisional (ICM) and acollisional (galaxies, dark matter) components of the cluster was observed for the first time and is often considered as a smoking gun for the presence of dark matter itself, since it ruled out alternative models of modified gravity (Clowe et al. 2006, ApJ, 648, L109). The similarity with 1E0657-56 led the authors to dub PSZ2 G282.28+49.94 the "Planck Bullet", and represents an ideal situation to provide astrophysical constraints to the self-interaction cross-section (σ/m) of dark matter particles. Further information in the paper I. Bartalucci, M. Rossetti, W. Boschin, et al. 2024, A&A, 689, A324 (see https://ui.adsabs.harvard.edu/abs/2024A%26A...689A.324B/abstract) Fig. 1. Trichromy of the "Planck Bullet" (filters g, r and i) obtained with DOLoRes@TNG. The white contours are the contour levels of the X-ray emission of the cluster as inferred from Chandra data (FOV~ 5.1x4.4 arcmin).
	Top ^ Home PDF Print Privacy