Constraining Baryons in the M31 galactic halo by Planck data

Tahir, Noraiz; Paolis, F. De; Qadir, Asghar; Nucita, A. A.

doi:10.1142/s0218271819500883

Cited by 10 publications

(14 citation statements)

References 26 publications

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“…One needs to then use some density distribution on an ad-hoc basis. We had used it to model the distribution of these clouds in the halo of M31 [21] and several other nearby spiral galaxies [22]. Here we will start from scratch, assuming that the clouds are exactly at the CMB temperature, so they are immersed in a heat bath which is the CMB and are completely merged with it.…”

Section: The Virial Modelmentioning

confidence: 99%

Virial clouds explaining the observed rotational asymmetry in the galactic halos

2019

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Rotation of galactic objects has been seen in the CMB that could be ascribed to molecular hydrogen clouds with, or without, dust contamination and contamination from other sources. We model the clouds using the canonical ensemble for pure molecular hydrogen, a mixture of hydrogen helium and or dust, in order to constrain the physical parameters of these clouds. Since, the clouds are cold, we justify the use of the canonical ensemble by explicitly calculating the interaction between the hydrogen molecules and the CMB photons and determining the time required for thermal equilibrium to be reached, and show that there is enough time for the equilibrium to be attained.

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Section: The Virial Modelmentioning

confidence: 99%

Virial clouds explaining the observed rotational asymmetry in the galactic halos

2019

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“…From an energetic point of view, the turbulence in the halo might be advected from the galactic disk, or might be driven locally by the differential rotation of the CGM of M31 as observed by XMM-Newton (Hodges-Kluck et al 2016) and Planck (Tahir et al 2019), or the proper motion of satellite galaxies in the halo of the galaxy with a velocity of a few ×100km/s (van der Marel et al 2019;Grcevich & Putman 2009;Watkins et al 2010). A further investigation on the property of the turbulence in M31's halo is beyond the scope of this work, but we note that in some previous literature, the authors generally considered a roughly 10 − 100 times larger diffusion coefficient for the halo than that of the Galactic disk (Feldmann et al 2013;Kalashev & Troitsky 2016;Liu et al 2019).…”

Section: Constraint On the Baryon Mass In The Halo Of M31mentioning

confidence: 99%

Measuring the Mass of Missing Baryons in the Halo of Andromeda Galaxy with Gamma-Ray Observations

Zhang

Liu

et al. 2021

ApJ

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One of the biggest mysteries in the modern cosmology and galaxy formation is the hideout of the "missing baryons". The leading theory of galaxy formation predicts that a huge amount of baryons resides around galaxies extending out to their virial radii in the form of diffuse and hot gas of 10 6 − 10 7 K, which is also known as the major component of the circumgalactic medium (CGM). Studies by various groups via different techniques, however, have not reached a consensus on the role of CGM in accounting for the missing baryons, with the estimated contribution ranging from a minor fraction to enclosing the baryon budget of the galaxy. In this work we attempt to measure the mass of missing baryons in CGM with a novel method based on the gamma-ray observations of the extended halo of the Andromeda Galaxy. Since cosmic-ray particles that are generated inside the galaxy will eventually escape to the CGM, they will produce gamma-ray emission via the proton-proton collision with CGM. Different from some traditional measurements which are sensitive only to gas in certain specific temperature range, the hadronic gamma-ray flux is sensitive to baryonic gases in all phases and does not rely on the metallicity in the halo. Our result suggests that the total baryon mass contained within the virial radius is less than (1.4 − 5) × 10 10 M according to the gamma-ray observation. It implies that the CGM of Andromeda Galaxy may not account for more than 30% of the missing baryons, but the result is subject to uncertainties from the diffusion coefficient of the CRs in the halo as well as the stellar mass and dark matter halo mass of the galaxy. This method will become more constraining provided better understandings on these issues and more sensitive gamma-ray telescopes in the future.

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“…One would normally use them outside the galactic core, but since we are interested in the halo, the problem is not very relevant. We used the Planck data first for the M31 halo [24]. The calculation requires an estimate of the mass and radius of the clouds, which we will discuss in the next section.…”

Section: Seeing the Galactic Halo Rotationmentioning

confidence: 99%

Virial clouds and rotational asymmetry in galactic haloes

Qadir

Paolis

2021

Arab. J. Math.

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In 1995, it was suggested that some of the baryonic dark matter in galaxies may be in the form of molecular hydrogen clouds, and a mechanism for observing them had been given. In the same year, a novel method of seeing the clouds was proposed, that is to look for a temperature asymmetry in the cosmic microwave background towards the M31 galaxy, due to a “Doppler effect” induced by the M31 halo rotation. This temperature asymmetry has since been seen and confirmed in M31 and other galaxies, and used to study the rotation of galactic haloes and map their dynamics. It had been questioned whether such clouds could actually exist, and in response, the clouds were modeled and shown to be possible. It then becomes necessary to trace the evolution of those clouds from their formation to the modern day. Here, the development of the ideas is reviewed.

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Constraining Baryons in the M31 galactic halo by Planck data

Cited by 10 publications

References 26 publications

Virial clouds explaining the observed rotational asymmetry in the galactic halos

Virial clouds explaining the observed rotational asymmetry in the galactic halos

Measuring the Mass of Missing Baryons in the Halo of Andromeda Galaxy with Gamma-Ray Observations

Virial clouds and rotational asymmetry in galactic haloes

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