Reply to comment on: "An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre"

TL;DR

This paper defends the original claim of Galactic Center Chimneys as a unified outflow structure, clarifying previous observations and addressing critiques with new data analysis.

Contribution

It provides a detailed response to critiques, reaffirming the Chimneys as a continuous, symmetrical outflow channel from the Galactic Center based on X-ray data.

Findings

The Chimneys are a continuous, symmetrical structure.

No clear evidence of over-ionised plasma at the Chimney locations.

The Chimneys may contribute to the Fermi Bubbles.

Abstract

In response to the comment posted by Nakashima et al. (arXiv:1903.1176), regarding prior claims for the features that we referred to as the Galactic Center Chimneys (2019, Nature, 567, 347), we point out the following: 1) The Nakashima et al. 2019 paper appeared in the arXiv on March 8th (1903.02571), after our paper was in the final stage of printing (accepted on January 30th). It is however interesting to see that the morphology of the brightest portions of the two results are in broad agreement (compare their Fig. 1 to our Extended Data Figs. 1 and 2). 2) Nakashima et al. 2013 ApJ 773, 20 claim the discovery of a blob of recombining plasma ~1deg south of Sgr A*, implying peculiar abundances. Again, their image (Fig. 1) agrees with the brightest portions of our images, although it does not show any direct connection between the plasma blob and the central parsec (e.g., such as the quasi-continuous chimney that we reported), nor evidence for an outflow from the center. We apologize for overlooking an appropriate citation to this contribution by Nakashima et al. 3) We fitted the XMM-Newton and Chandra data at the same position of the claimed recombining plasma and we did not find any clear-cut evidence for the presence of either an over-ionised plasma or peculiar abundances. Future X-ray calorimetric observations will presumably clarify this disagreement. 4) The continuity of the Chimney features, their quasi-symmetrical placement relative to Sgr A*, and their relatively sharp and well-defined edges are the essential features of our data that have led us to propose that the Chimneys are a unified columnar structure that represents a channel for the outflow of energy from the central region, possibly contributing to the stocking of the relativistic particle population manifested in the Fermi Bubbles.

Full text

Reply to comment on: ”An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre”

G. Ponti1,2, F. Hofmann1, E. Churazov3,4, M. R. Morris5, F. Haberl1, K. Nandra1, R. Terrier6, M. Clavel7, and A. Goldwurm6,8

1 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany

2 INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (LC), Italy

3 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748, Garching, Germany

4 Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117997, Russia

5 Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA

6 Unité mixte de recherche Astroparticule et Cosmologie, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris, France

7 Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France

8 Service d’Astrophysique (SAp), IRFU/DSM/CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France

††pagerange: Reply to comment on: ”An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre”–LABEL:lastpage

In response to the comment posted by Nakashima et al. (arXiv:1903.1176), regarding prior claims for the features that we referred to as the Galactic Center Chimneys (2019, Nature, 567, 347), we point out the following:

The Nakashima et al. 2019 paper appeared in the arXiv on March 8th (1903.02571), after our paper was in the final stage of printing (accepted on January 30th). It is however interesting to see that the morphology of the brightest portions of the two results are in broad agreement (compare their Fig. 1 to our Extended Data Figs. 1 and 2). 2. 2.

Nakashima et al. 2013 ApJ 773, 20 claim the discovery of a blob of recombining plasma $\sim 1^{\circ}$ south of Sgr A*⋆*, implying peculiar abundances. Again, their image (Fig. 1) agrees with the brightest portions of our images, although it does not show any direct connection between the plasma blob and the central parsec (e.g., such as the quasi-continuous chimney that we reported), nor evidence for an outflow from the center. We apologize for overlooking an appropriate citation to this contribution by Nakashima et al. 3. 3.

We fitted the XMM-Newton and Chandra data at the same position of the claimed recombining plasma and we did not find any clear-cut evidence for the presence of either an over-ionised plasma or peculiar abundances. Future X-ray calorimetric observations will presumably clarify this disagreement. 4. 4.

The continuity of the Chimney features, their quasi-symmetrical placement relative to Sgr A*⋆*, and their relatively sharp and well-defined edges are the essential features of our data that have led us to propose that the Chimneys are a unified columnar structure that represents a channel for the outflow of energy from the central region, possibly contributing to the stocking of the relativistic particle population manifested in the Fermi Bubbles.