Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.34579

O VI Emission in Starbursting BCGs: An HST-COS Extension of "Reigniting the FUSE"

Michael Reefe·Michael McDonald·Marios Chatzikos·Megan Donahue·Andrew C. Fabian·Massimo Gaspari·Eric Miller·Valeria Olivares·Taweewat Somboonpanyakul·G. Mark Voit
View original source ↗Read source document ↗Export metadata ↓

Abstract

In this extension of our "Reigniting the FUSE" series, we have obtained new far-ultraviolet spectroscopy of 3 starbursting brightest cluster galaxies with the Cosmic Origins Spectrograph (COS) aboard HST. With these new data, in combination with archival COS data of 2 additional systems, we measure star formation rates (SFRs) from the young stellar continuum and cooling rates through $10^{5.5}$ K gas with the O VI $1032,1038\,\mathring{\rm A}$ doublet ($\dot{M}_{\rm O\,VI}$). We use these measurements to increase the size of the "Reigniting the FUSE" sample, which itself contains high resolution far UV spectroscopy for 29 nearby massive elliptical galaxies from FUSE, and extend it 1 dex upwards in SFR and cooling rate. Our derived SFRs agree well with photometric GALEX$+$WISE SFRs from the literature. The new data also reinforce the previously observed trend in cooling efficiency ($\dot{M}_{\rm O\,VI}/\dot{M}_{\rm max}$; where $\dot{M}_{\rm max}$ is the X-ray luminosity-based cooling rate) versus mass, with groups cooling more efficiently than clusters by a factor of $\sim$4-5. When we isolate a sample of the most star-forming central galaxies, we find that the star formation rates, X-ray spectroscopic cooling rates, and UV spectroscopic cooling rates are all consistent with one another, on average, while retaining substantial system-to-system scatter, reflecting time-depenent multiphase condensation and cold gas reservoir evolution. The remainder of the sample, in contrast, overwhelmingly shows ratios of ${\rm SFR}/\dot{M}_{\rm O\,VI} \sim {\rm SFR}/\dot{M}_{\rm X,spec} \sim 10\%$.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Michael Reefe, Michael McDonald, Marios Chatzikos, Megan Donahue, Andrew C. Fabian, Massimo Gaspari, Eric Miller, Valeria Olivares, Taweewat Somboonpanyakul, G. Mark Voit. 2026-10-25. O VI Emission in Starbursting BCGs: An HST-COS Extension of "Reigniting the FUSE". https://arxiv.org/abs/2610.34579

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

JWST Spectroscopic Census of ALMA Faint Submillimeter Galaxies in the Hubble Ultra Deep Field

We present a JWST/NIRSpec rest-frame optical spectroscopic census of ALMA 1-mm continuum sources in the Hubble Ultra Deep Field (UDF) identified by the deep ALMA UDF and ASPECS programs. Our sample is composed of the ALMA flux-limited ($S_{1\,\mathrm{mm}}\gtrsim 0.1\,\mathrm{mJy}$) sources observed with medium-resolution NIRSpec spectroscopy from JADES and SMILES, 16 faint submillimeter galaxies (SMGs) at spectroscopic redshifts of $z\sim 1$-$4$. These SMGs show bright longer-wavelength optical lines (H$α$, [N II]$λ\lambda6548,6583$, and [S II]$λ\lambda6717,6731$) and faint shorter-wavelength optical lines (H$β$ and [O III]$λ\lambda4959,5007$) with a large nebular attenuation, $E(B-V)\sim0.3$-$1.8$. We test the SMGs using BPT diagnostics and Chandra X-ray fluxes, and find that most SMGs are classified as AGNs; the AGN fraction is $\sim80\%$ for the SMGs at $M_*>10^{10.5} M_\odot$. We find only one SMG ($<10\%$) with a broad Balmer line, indicating that the SMGs are predominantly obscured AGNs. With the optical lines, we estimate the metallicities of the SMGs to be moderately high, $\sim0.4$-$2 Z_\odot$, exceeding the model-predicted dust-growth critical metallicity ($\sim0.1$-$0.2Z_\odot$), which naturally explains the dusty nature of the SMGs. Interestingly, the SMGs fall in the mass-metallicity relation and the star-formation main sequence, showing no significant differences from other high-$z$ galaxies. Similarly, we find electron densities of $n_e\sim10^2$-$10^3\,\mathrm{cm}^{-3}$ for the SMGs that are comparable with other high-$z$ galaxies. Together with the high SMG fraction ($\sim 100\%$) at the massive end ($M_*>10^{10.5} M_\odot$), these results indicate that the SMGs are mostly not special, but typical massive star-forming galaxies at high redshift.

astro-ph.GA↗
arXiv2026

On the relation between magnetic field strength and gas density in the interstellar medium. II. Density uncertainties and diffuse gas constraints

The relationship between magnetic field strength and gas density is essential to understand the interstellar medium and star formation. Zeeman measurements in dense atomic and molecular gas phases have traditionally been used to directly probe magnetic field strengths in the Milky Way. This allowed derivation of a relationship between magnetic field strength $B$ and gas number density $n$. We recently generalized this relation as a two-part power-law with non-zero slopes and a transition density given as $B/B_0 \propto (n/n_0)^{α_1}$ for $n \le n_0$ and $(n/n_0)^{α_2}$ for $n > n_0$. Here, we extend our previous hierarchical Bayesian framework by incorporating a large body of pulsar observations that probe the diffuse interstellar medium and explicitly modelling density uncertainties through a log-density intrinsic scatter $R_n$ applied to all densities. We also account for magnetic field geometry and measurement uncertainties through a magnetic hyperparameter to estimate $B$. This results in a stronger constraint on the diffuse gas part of the $B$--$n$ relation. Our results confirm a non-zero exponent in the diffuse gas and a broad transition density with our best model and data set yielding maximum a posteriori results of $α_1 = 0.20^{+0.01}_{-0.03}$, $α_2 = 0.65^{+0.06}_{-0.07}$, $n_0 = 3330^{+270}_{-3220}\,\text{cm}^{-3}$, and $B_0 = 10.11^{+0.71}_{-5.97}\,μ\text{G}$.

astro-ph.GA↗
arXiv2026

Where did all the Little Red Dots go? The abundance of LRD analogues among objects with broad lines at $z < 0.35$

One of the most puzzling discoveries since the launch of the James Webb Space Telescope is a numerous population of sources at high redshift nicknamed ``Little Red Dots'' (LRDs). Characterized by broad Balmer emission lines, compact morphologies and v-shaped spectral energy distributions (SEDs) in the rest-frame optical, the nature of LRDs remains elusive. A major challenge is the high redshift nature of LRDs, which makes observations very expensive and difficult. Finding local LRD analogues is a crucial step in unravelling the physical processes giving rise to LRDs, as cheaper observations with many facilities would become available. In this paper, we conduct a search for local LRD analogues by starting from an unbiased parent catalogue of all SDSS objects with broad H$α$ or H$β$ emission lines (both galaxies and quasars) at $0 < z < 0.35$, complemented by archival photometry and spectroscopy. We find that among broad-line objects, $19\%$ show a v-shaped SED. We then select objects whose SED is well described by a modified black body (MBB), and identify nine local LRD analogues. After accounting for selection limitations we get an abundance of $0.08\%$ of all objects with broad lines. Among only objects which match the typical continuum and emission line luminosities of LRDs, $5\%$ display a v-shape and $0.37\%$ display a MBB-like SED. We recover one previously-identified local LRD analogue (the so-called ``Egg''), validating our methodology. Among the other eight analogues, one (J0302$-$0101) shows all the hallmarks of an LRD despite being visibly embedded in the core of a galaxy; another object is ambiguous, and the remaining six may have alternative explanations for their peculiar SEDs. Our study highlights that LRDs are extremely rare at $z < 0.35$; we find very few objects with broad lines which have LRD-like SEDs, even without attempting to match the compactness of LRDs.

astro-ph.GA↗