Alone on a wide wide sea. The origin of SECCO 1, an isolated star-forming gas cloud in the Virgo cluster*†‡

Bellazzini, M.; Armillotta, Lucia; Perina, S.; Magrini, L.; Cresci, G.; Beccari, G.; Battaglia, G.; Fraternali, Filippo; Zeeuw, P. T. de; Martín, Nicolás F.; Calura, F.; Ibata, Rodrigo; Coccato, L.; Testa, V.; Correnti, Matteo

doi:10.1093/mnras/sty467

Cited by 19 publications

(30 citation statements)

References 97 publications

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“…However, de los Reyes & Kennicutt (2019) have recently shown that in local dwarf galaxies the Schmidt law for star formation (Schmidt 1959) does not seem to exhibit any threshold, as even the lowest surface brightness regions show the presence of very young stars. An even more extreme confirmation of this is represented by an utterly low density (n ∼ 0.01 cm −3 ) -yet, star-forming -galaxy recently found in the Virgo cluster (Bellazzini et al 2018). All in all, since UFDs are thought to represent the extreme limit of the galaxy formation process (Simon 2019), the assumed gas and star distributions for our model Boötes I galaxy may well be not quite so unreasonable.…”

Section: Numerical Set-upsupporting

confidence: 54%

High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies

Romano

Calura

D’Ercole

et al. 2019

A&A

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Context. The faintest Local Group galaxies found lurking in and around the Milky Way halo provide a unique test bed for theories of structure formation and evolution on small scales. Deep Subaru and Hubble Space Telescope photometry demonstrates that their stellar populations are old, and that the star formation activity did not last longer than 2 Gyr in these systems. A few mechanisms that may lead to such a rapid quenching have been investigated by means of hydrodynamic simulations, without providing any final assessment so far. Aims. This is the first in a series of papers aimed at analysing the roles of stellar feedback, ram pressure stripping, host-satellite tidal interactions and reionization in cleaning the lowest-mass Milky Way companions of their cold gas, by using high-resolution, three-dimensional hydrodynamic simulations. Methods. We simulate an isolated ultrafaint dwarf galaxy loosely modeled after Boötes I, and examine whether or not stellar feedback alone could drive a substantial fraction of the ambient gas out from the shallow potential well. Results. In contrast to simple analytical estimates, but in agreement with previous hydrodynamical studies, we find that most of the cold gas reservoir is retained. Conversely, a significant fraction of the metal-enriched stellar ejecta crosses the boundaries of the computational box with velocities exceeding the local escape velocity and is, thus, likely lost from the system. Conclusions. Although the total energy output from multiple supernova explosions exceeds the binding energy of the gas, no galacticscale outflow develops in our simulations and as such, most of the ambient medium remains trapped within the weak potential well of the model galaxy. It seems thus unavoidable that, in order to explain the dearth of gas in ultrafaint dwarf galaxies, we will have to resort to environmental effects. This will be the subject of a forthcoming paper.

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Section: Numerical Set-upsupporting

confidence: 54%

High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies

Romano

Calura

D’Ercole

et al. 2019

A&A

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“…SECCO 1 is a faint, star-forming stellar system with some diffuse Hα emission. Its physical size, ∼ 1.2 kpc in radius for each of the two pieces (Bellazzini et al 2018), is much smaller than the OC discussed in this paper. It has a rather high metallicity of ∼ half solar for its low optical luminosity (Beccari et al 2017;Sand et al 2017).…”

Section: Origin Of the Ocmentioning

confidence: 61%

“…none found in the Hα surveys in the Coma cluster, A851, and CL0024+17 (Yagi et al 2010(Yagi et al , 2015. The only other isolated Hα cloud in a galaxy cluster we are aware of is SECCO 1 in the Virgo cluster (Beccari et al 2017;Sand et al 2017;Bellazzini et al 2018). SECCO 1 is a faint, star-forming stellar system with some diffuse Hα emission.…”

Section: Origin Of the Ocmentioning

confidence: 89%

An H$α$/X-ray orphan cloud as a signpost of the intracluster medium clumping

Ge,

Luo,

Sun

et al. 2021

Preprint

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Recent studies have highlighted the potential significance of intracluster medium (ICM) clumping and its important implications for cluster cosmology and baryon physics. Many of the ICM clumps can originate from infalling galaxies, as stripped interstellar medium (ISM) mixing into the hot ICM. However, a direct connection between ICM clumping and stripped ISM has not been unambiguously established before.Here we present the discovery of the first and still the only known isolated cloud (or orphan cloud; OC) detected in both X-rays and Hα in the nearby cluster A1367. With an effective radius of 30 kpc, this cloud has an average X-ray temperature of 1.6 keV, a bolometric X-ray luminosity of ∼ 3.1 × 10 41 erg s −1 and a hot gas mass of ∼ 10 10 M . From the MUSE data, the OC shows an interesting velocity gradient nearly along the east-west direction with a low level of velocity dispersion of ∼ 80 km s −1 , which may suggest a low level of the ICM turbulence. The emission line diagnostics suggest little star formation in the main Hα cloud and a LI(N)ER-like spectrum, but the excitation mechanisms remain unclear. This example shows that stripped ISM, even long after the initial removal from the galaxy, can still induce ICM inhomogeneities. We suggest that the magnetic field can stabilize the OC by suppressing hydrodynamic instabilities and thermal conduction. This example also suggests that at least some ICM clumps are multi-phase in nature and implies that the ICM clumps can also be traced in Hα. Thus, future deep and wide-field Hα surveys can be used to probe the ICM clumping and turbulence.

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“…In particular aE is nearly filamentary, with a shell morphology that is observed If PW 1 is indeed the product of a small recent episode of star formation that occurred within a cold gas cloud, associated or not associated with the MS (see below) and likely triggered by interaction with Galactic gas, an interesing similarity, albeit at a smaller scale, can be noted with SECCO 1 (see Bellazzini et al 2018, and references therein). This is a low mass (M * = 10 5 M ) star-forming system (with no detection of stars older than ∼ 50 Myr) located in the outskirts of the Virgo cluster of galaxies, that is the possible prototype of a new class of stellar systems that are born in isolated H i clouds kept together by the external pressure of the surrounding hot gas (Sand 2017;Bellazzini et al 2018). SECCO 1 is fragmented in two pieces, each one with size of a few hundreds of pc, and will probably fragment into smaller pieces in the near future.…”

Section: Discussionmentioning

confidence: 99%

Young stars raining through the Galactic Halo: the nature and orbit of Price-Whelan 1

Bellazzini,

Ibata,

Martin

et al. 2019

Preprint

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We present radial velocities for five member stars of the recently discovered young (age 100 − 150 Myr) stellar system Price-Whelan 1 (PW 1), that is located far away in the Galactic Halo (D 29 kpc, Z 15 kpc), and that is probably associated to the Leading Arm (LA) of the Magellanic Stream. We measure the systemic radial velocity of PW 1, V r = 275 ± 10 km/s, significantly larger than the velocity of the LA gas in the same direction. We re-discuss the main properties and the origin of this system in the light of these new observations, computing the orbit of the system and comparing its velocity with that of the H i in its surroundings. We show that the bulk of the gas at the velocity of the stars is more than 10 • (5 kpc) away from PW 1 and the velocity difference between the gas and the stars become larger as gas closer to the stars is considered. We discuss the possibilities that (a) the parent gas cloud was dissolved by the interaction with the Galactic gas, and (b) that the parent cloud is the high velocity cloud HVC 287.5+22.5+240, lagging behind the stellar system by 25 km/s and 10 • 5 kpc. This HVC, that is part of the LA, has metallicity similar to PW 1, displays a strong magnetic field that should help to stabilise the cloud agains ram pressure, and shows traces of molecular hydrogen. We also show that the system is constituted of three distinct pieces that do not differ only by position in the sky but also by stellar content.

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Alone on a wide wide sea. The origin of SECCO 1, an isolated star-forming gas cloud in the Virgo cluster*†‡

Cited by 19 publications

References 97 publications

High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies

High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies

An H$α$/X-ray orphan cloud as a signpost of the intracluster medium clumping

Young stars raining through the Galactic Halo: the nature and orbit of Price-Whelan 1

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