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A feather on the hat: tracing the giant stellar stream around the Sombrero galaxy

Martínez-Delgado, David and Román, Javier and Erkal, Denis and Schirmer, Mischa and Roca-Fàbrega, Santi and Laine, Seppo and Donatiello, Giuseppe and Jimenez, Manuel and Malin, David and Carballo-Bello, Julio A. (2021) A feather on the hat: tracing the giant stellar stream around the Sombrero galaxy. Monthly Notices of the Royal Astronomical Society, 506 (4). pp. 5030-5038. ISSN 0035-8711. doi:10.1093/mnras/stab1874.

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Recent evidence of extremely metal-rich stars found in the Sombrero galaxy (M104) halo suggests that this galaxy has undergone a recent major merger with a relatively massive galaxy. In this paper, we present wide-field deep images of the M104 outskirts obtained with a 18-cm amateur telescope with the purpose of detecting any coherent tidal features from this possible major merger. Our new data, together with a model of the M104 inner halo and scattered light from stars around the field, allow us to trace for the first time the full path of the stream on both sides of the disc of the galaxy. We fully characterize the ring-like tidal structure and we confirm that this is the only observable coherent substructure in the inner halo region. This result is in agreement with the hypothesis that M104 was created by a wet major merger more than 3.5 Gyr ago that heated up the stellar population, blurring all old substructure. We generated a set of numerical models that reproduce the formation of the observed tidal structure. Our best-fitting model suggests the formation of this stream in the last 3 Gyr is independent of the wet major merger that created the M104 system. Therefore, the formation of the tidal stream can put a constraint on the time when the major merger occurred.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemGaia ItemDPAC
Martínez-Delgado, David0000-0003-3835-2231
Román, Javier0000-0002-3849-3467
Erkal, Denis0000-0002-8448-5505
Schirmer, Mischa0000-0003-2568-9994
Roca-Fàbrega, Santi0000-0002-6299-152X
Laine, Seppo0000-0003-1250-8314
Jimenez, Manuel0000-0002-8651-9377
Carballo-Bello, Julio A.0000-0002-3690-105X
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 June 25. Received 2021 June 21; in original form 2021 June 9. Published: 20 July 2021. DMD devotes this paper to Prof. Jose Luis Comellas, who guided him to find the Sombrero galaxy from his home rooftop in the 1980s. DMD acknowledges financial support from the Talentia Senior Program (through the incentive ASE-136) from Secretaría General de Universidades, Investigación y Tecnología, de la Junta de Andalucía. DMD and JR acknowledge funding from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). JR acknowledges support from the Spanish State Research Agency (AEI-MCINN) of the Spanish Ministry of Science and Innovation under the grant ‘The structure and evolution of galaxies and their central regions’ with reference PID2019-105602GB-I00/10.13039/501100011033 and financial support from the grants AYA2015-65973-C3-1-R and RTI2018-096228-B-C31 (MINECO/FEDER, UE). DMD also recognizes funds from the research project AYA 2007-65090. THELI made use of the following tools and data products: Source Extractor (Bertin & Arnouts 1996), Scamp (Bertin 2006), Swarp (Bertin et al. 2002), and the VizieR catalogue access tool, CDS, Strasbourg, France. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Data Availability: The data underlying this article will be shared on a reasonable request to the corresponding author.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Junta de AndalucíaASE-136
Severo OchoaSEV-2017-0709
Ministerio de Ciencia e Innovación (MCINN)PID2019-105602GB-I00
Ministerio de Economía, Industria y Competitividad (MINECO)AYA2015-65973-C3-1-R
Ministerio de Ciencia, Innovación y Universidades (MCIU)RTI2018-096228-B-C31
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)AYA 2007-65090
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:galaxies: formation – galaxies: haloes – galaxies: individual: M104 – galaxies: interaction
Issue or Number:4
Record Number:CaltechAUTHORS:20211110-213221409
Persistent URL:
Official Citation:David Martínez-Delgado, Javier Román, Denis Erkal, Mischa Schirmer, Santi Roca-Fàbrega, Seppo Laine, Giuseppe Donatiello, Manuel Jimenez, David Malin, Julio A Carballo-Bello, A feather on the hat: tracing the giant stellar stream around the Sombrero galaxy, Monthly Notices of the Royal Astronomical Society, Volume 506, Issue 4, October 2021, Pages 5030–5038,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111832
Deposited By: Tony Diaz
Deposited On:11 Nov 2021 18:35
Last Modified:11 Nov 2021 18:35

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