A Nascent Tidal Dwarf Galaxy Forming within the Northern H i Streamer of M82

Pasha, I. I.; Lokhorst, Deborah; Dokkum, Pieter van; Chen, Seery; Abraham, Roberto; Greco, Johnny P.; Danieli, Shany; Miller, Tim B.; Lippitt, Erin; Polzin, Ava; Shen, Zili; Keim, Michael A.; Liu, Qing; Merritt, Allison; Zhang, Jielai

doi:10.3847/2041-8213/ac3ca6

Cited by 8 publications

(10 citation statements)

References 48 publications

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“…The detection of low surface brightness (LSB) features, such as tidal tails and diffuse galaxies, can be challenging, particularly in crowded fields. In Figure 6 we show cutouts of a wide-field continuum-subtracted Hα image of the M81 group, taken with the Dragonfly Spectral Line Mapper pathfinder (Pasha et al 2021;Lokhorst et al 2022). A typical contaminant in continuum-subtracted imaging are residuals of bright stars, as saturation, color terms, and imperfect PSF matching can lead to strong residuals.…”

Section: Wide Field Low Surface Brightness Imagingmentioning

confidence: 99%

A Robust and Simple Method for Filling in Masked Data in Astronomical Images

van Dokkum,

Pasha

2024

PASP

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Astronomical images often have regions with missing or unwanted information, such as bad pixels, bad columns, cosmic rays, masked objects, or residuals from imperfect model subtractions. In certain situations it can be essential, or preferable, to fill in these regions. Most existing methods use low order interpolations for this task. In this paper a method is described that uses the full information that is contained in the pixels just outside masked regions. These edge pixels are extrapolated inwards, using iterative median filtering. This leads to a smoothly varying spatial resolution within the filled-in regions, and ensures seamless transitions between masked pixels and good pixels. Gaps in continuous, narrow features can be reconstructed with high fidelity, even if they are large. The method is implemented in maskfill, an open-source MIT licensed Python package (https://github.com/dokkum/maskfill). Its performance is illustrated with several examples, and compared to several alternative interpolation schemes.

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Section: Wide Field Low Surface Brightness Imagingmentioning

confidence: 99%

A Robust and Simple Method for Filling in Masked Data in Astronomical Images

van Dokkum,

Pasha

2024

PASP

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“…However, these clouds offer the unique opportunity to test star formation laws at extremely low rates where gas physical conditions are different than in disk galaxies (with no rotational support and no stellar disk driving supersonic turbulence). Stochasticity at the upper end of the stellar initial mass function (IMF) and density dependencies of the CO-to-H 2 conversion factor (Lamers et al 2002;da Silva et al 2014;Hu et al 2022) requires some caution in interpreting the results; nevertheless, understanding star formation in extragalactic clouds of tidal origin is very relevant because we might capture the slow build-up process of diffuse dwarf galaxy formation (Pasha et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Exploring extreme conditions for star formation: A deep search for molecular gas in the Leo ring

Corbelli

Thilker

Mannucci

et al. 2023

A&A

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Aims. We carried out sensitive searches for the 12CO J = 1–0 and J = 2–1 lines in the giant extragalactic HI ring in Leo to investigate the star formation process within environments where gas metallicities are close to solar, but physical conditions are different than those typical of bright galaxy disks. Our aim is to check the range of validity of known scaling relations. Methods. We used the IRAM-30 m telescope to observe 11 regions close to HI gas peaks or where sparse young massive stars have been found. For all pointed observations we reached spectral noise between 1 and 5 mK for at least one of the observed frequencies at 2 km s−1 spectral resolution. Results. We marginally detect two 12CO J = 1–0 lines in the star-forming region Clump 1 of the Leo ring, whose radial velocities are consistent with those of Hα lines, but whose line widths are much smaller than observed for virialized molecular clouds of similar mass in galaxies. The low signal-to-noise ratio, the small line widths, and the extremely low number densities inferred by virialized cloud models suggest that a more standard population of molecular clouds, still undetected, might be in place. Using upper limits to the CO lines, the most sensitive pointed observations show that the molecular gas mass surface density is lower than expected from the extrapolation of the molecular Kennicutt–Schmidt relation established in the disk of galaxies. The sparse stellar population in the ring, possibly forming ultra diffuse dwarf galaxies, might then be the result of a short molecular gas depletion time in this extreme environment.

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“…Given the very low stellar mass, the high mean metallicity ( ( ) 12 log O H 8.38 0.11 á + ñ=  ) implies that the gas fueling the star formation in SECCO 1 was stripped from a relatively massive gas-rich galaxy (Beccari et al 2017;Sand et al 2017;Bellazzini et al 2018), either by a tidal interaction or by ram pressure exerted by the hot intracluster medium (ICM). Indeed, star formation is known to occur in gas clouds stripped from galaxies via both channels (see, e.g., Poggianti et al 2019;Pasha et al 2021, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. I. 2D Optical Spectroscopy

Bellazzini

Magrini

Jones

et al. 2022

ApJ

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We use panoramic optical spectroscopy obtained with the Very Large Telescope/MUSE to investigate the nature of five candidate extremely isolated low-mass star-forming regions (Blue Candidates; hereafter, BCs) toward the Virgo cluster of galaxies. Four of the five (BC1, BC3, BC4, and BC5) are found to host several H ii regions and to have radial velocities fully compatible with being part of the Virgo cluster. All the confirmed candidates have mean metallicity significantly in excess of that expected from their stellar mass, indicating that they originated from gas stripped from larger galaxies. In summary, these four candidates share the properties of the prototype system SECCO 1, suggesting the possible emergence of a new class of stellar systems, intimately linked to the complex duty cycle of gas within clusters of galaxies. A thorough discussion of the nature and evolution of these objects is presented in a companion paper, where the results obtained here from the MUSE data are complemented with Hubble Space Telescope (optical) and Very Large Array (Hi) observations.

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A Nascent Tidal Dwarf Galaxy Forming within the Northern H i Streamer of M82

Cited by 8 publications

References 48 publications

A Robust and Simple Method for Filling in Masked Data in Astronomical Images

A Robust and Simple Method for Filling in Masked Data in Astronomical Images

Exploring extreme conditions for star formation: A deep search for molecular gas in the Leo ring

Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. I. 2D Optical Spectroscopy

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