Hundreds of Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) Survey

Salehirad, Sheyda; Reines, Amy E.; Molina, Mallory

doi:10.3847/1538-4357/ac8876

Cited by 19 publications

(11 citation statements)

References 100 publications

(206 reference statements)

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“…The descendants of the galaxies hosting overmassive black holes at 0.35 < z < 1 in the simulation show a wide distribution of stellar masses, with 13% of them having M *  10 9 M e and hence to host overmassive black holes at z = 0 (as already found observationally in a few cases; e.g., Secrest et al 2017;Salehirad et al 2022). On the other hand, 35% of them (roughly one-third) evolve into ordinary M * > 10 10 M e galaxies, hence becoming "normal" systems (i.e., massive galaxies hosting SMBHs).…”

Section: Discussionsupporting

confidence: 72%

Overmassive Black Holes in Dwarf Galaxies Out to z ∼ 0.9 in the VIPERS Survey

Mezcua

Siudek

Suh

et al. 2023

ApJL

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Supermassive black holes (SMBHs) are thought to originate from early universe seed black holes of mass M BH ∼ 102–105 M ⊙ and grown through cosmic time. Such seeds could be powering the active galactic nuclei (AGN) found in today’s dwarf galaxies. However, probing a connection between the early seeds and local SMBHs has not yet been observationally possible. Massive black holes hosted in dwarf galaxies at intermediate redshifts, on the other hand, may represent the evolved counterparts of the seeds formed at very early times. We present a sample of seven broad-line AGN in dwarf galaxies with a spectroscopic redshift ranging from z = 0.35 to z = 0.93. The sources are drawn from the VIPERS survey as having an Large Magellanic Cloud (LMC) like stellar mass (M ∗) derived from spectral energy distribution fitting, and they are all star-forming galaxies. Six of these sources are also X-ray AGN. The AGN are powered by SMBHs of >107 M ⊙, more massive than expected from the M BH–M ∗ scaling relation of AGN. Based on semianalytical simulations, we find that these objects are likely overmassive with respect to their hosts since early times (z > 4), independently of whether they formed as heavy (∼105 M ⊙) or light (∼102 M ⊙) seed black holes. In our simulations, these objects tend to grow faster than their host galaxies, contradicting models of synchronized growth. The host galaxies are found to possibly evolve into massive systems by z ∼ 0, indicating that local SMBHs in massive galaxies could originate in dwarf galaxies hosting seed black holes at higher z.

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Section: Discussionsupporting

confidence: 72%

Overmassive Black Holes in Dwarf Galaxies Out to z ∼ 0.9 in the VIPERS Survey

Mezcua

Siudek

Suh

et al. 2023

ApJL

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“…The FWHM of the broad Hα line from the 1″ diameter circular aperture centered on Nucleus 1 is 446 ± 17 km s −1 . The total luminosity of the broad component is ≈ 1.5 × 10 38 erg s −1 , comparable to that found in the well-known type 1 dwarf AGN NGC 4395 (Brum et al 2019), and considerably lower than the broad-line luminosities of previously identified low-mass broad-line AGNs in the dwarf-galaxy population (e.g., Greene & Ho 2007;Reines et al 2013;Salehirad et al 2022), as might be expected for a galaxy with a stellar mass at least 1-3 orders of magnitude lower than that of any previous dwarf galaxy with an identified broad-line AGN (e.g., Baldassare et al 2016;Salehirad et al 2022). Note that the broad line disappears when the extraction aperture size is increased to match the SDSS aperture size, indicating that its origin is from an extremely compact region centered on the nucleus.…”

Section: Broad-line Detectionsupporting

confidence: 69%

Nuclear Activity in the Low-metallicity Dwarf Galaxy SDSS J0944-0038 : A Glimpse into the Primordial Universe

Reefe

Satyapal

Sexton

et al. 2023

ApJL

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Local low-metallicity dwarf galaxies are relics of the early universe and are thought to hold clues into the origins of supermassive black holes. While recent studies are uncovering a growing population of active galactic nuclei (AGNs) in dwarf galaxies, the vast majority reside in galaxies with solar or supersolar metallicities and stellar masses comparable to that of the LMC. Using Multi-Unit Spectroscopic Explorer (MUSE) and Very Large Telescope observations, we report the detection of [Fe x] λ6374 coronal line emission and a broad Hα line in the nucleus of SDSS J094401.87−003832.1, a nearby (z = 0.0049) metal-poor dwarf galaxy almost 500 times less massive than the LMC. Unlike the emission from the lower-ionization nebular lines, the [Fe x] λ6374 emission is compact and centered on the brightest nuclear source, with a spatial extent of ≈100 pc, similar to that seen in well-known AGNs. The [Fe x] luminosity is ≈1037 erg s−1, within the range seen in previously identified AGNs in the dwarf-galaxy population. The [Fe x] emission has persisted over the roughly 19 yr time period between the SDSS and MUSE observations, ruling out supernovae as the origin for the emission. The FWHM of the broad component of the Hα line is 446 ± 17 km s−1 and its luminosity is ≈1.5 × 1038 erg s−1, corresponding to a black hole mass of ≈ 3150 M ⊙, in line with its stellar mass if virial mass relations and black hole–galaxy scaling relations apply in this mass regime. These observations, together with previously reported multiwavelength observations, can most plausibly be explained by the presence of an accreting intermediate-mass black hole in a primordial galaxy analog.

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“…Salehirad et al (2022) identified 388 low mass AGN hosts in the GAMA DR4 equatorial and G23 regions consistent with our definition of low mass (log M * /M ≤ 10). Of this sample, 53 lie in G23.…”

supporting

confidence: 76%

“…These low mass hosts are weaker in their radio emission as well compared to those identified by other methods. A crossmatch with the low mass AGN hosts in GAMA G23 compiled by Salehirad et al (2022) also confirms that the SED-based low mass AGN hosts are unique to PROSPECT. Narrow-line diagnostics appear to struggle in identifying AGN in low mass galaxies.…”

Section: Discussionsupporting

confidence: 55%

EMU/GAMA: A technique for detecting active galactic nuclei in low mass systems

Prathap,

Hopkins,

Robotham

et al. 2024

Publ. Astron. Soc. Aust.

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We propose a new method for identifying active galactic nuclei (AGN) in low mass (M* ≤ 1010M⊙) galaxies. This method relies on spectral energy distribution (SED) fitting to identify galaxies whose radio flux density has an excess over that expected from star formation alone. Combining data in the Galaxy and Mass Assembly (GAMA) G23 region from GAMA, Evolutionary Map of the Universe (EMU) early science observations, andWide-field Infrared Survey Explorer (WISE), we compare this technique with a selection of different AGN diagnostics to explore the similarities and differences in AGN classification. We find that diagnostics based on optical and near-infrared criteria (the standard BPT diagram, the WISE colour criterion, and the mass-excitation, or MEx diagram) tend to favour detection of AGN in high mass, high luminosity systems, while the “ProSpect” SED fitting tool can identify AGN efficiently in low mass systems. We investigate an explanation for this result in the context of proportionally lower mass black holes in lower mass galaxies compared to higher mass galaxies and differing proportions of emission from AGN and star formation dominating the light at optical and infrared wavelengths as a function of galaxy stellar mass. We conclude that SED-derived AGN classification is an efficient approach to identify low mass hosts with low radio luminosity AGN.

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Hundreds of Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) Survey

Cited by 19 publications

References 100 publications

Overmassive Black Holes in Dwarf Galaxies Out to z ∼ 0.9 in the VIPERS Survey

Overmassive Black Holes in Dwarf Galaxies Out to z ∼ 0.9 in the VIPERS Survey

Nuclear Activity in the Low-metallicity Dwarf Galaxy SDSS J0944-0038 : A Glimpse into the Primordial Universe

EMU/GAMA: A technique for detecting active galactic nuclei in low mass systems

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