Variable Hard-X-Ray Emission From the Candidate Accreting Black Hole in Dwarf Galaxy Henize 2–10

Whalen, Thomas J.; Hickox, Ryan C.; Reines, Amy E.; Greene, Jenny E.; Sivakoff, G. R.; Johnson, K. E.; Alexander, D. M.; Goulding, Andy D.

doi:10.1088/0004-637x/806/1/37

Cited by 8 publications

(11 citation statements)

References 34 publications

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“…Assuming a common spectral shape in each of the three observations, we measure unabsorbed 0.3-10.0 keV fluxes of (5.09 +1.68 −1.24 , 0.17 +0.09 −0.07 , and 1.28 +0.47 −0.38 ) × 10 −13 erg s −1 cm −2 respectively (90% confidence intervals), i.e., variability of a factor of ∼ 30. The large-amplitude variability (also see Whalen et al 2015) and the large luminosity in the 2001 observation (≥ 10 39 erg s −1 ) suggests it is an X-ray binary (XRB) containing a stellar-mass BH primary.…”

Section: Observations and Data Reductionmentioning

confidence: 94%

Deep Chandra Observations of the Compact Starburst Galaxy Henize 2–10: X-Rays From the Massive Black Hole

Reines

Reynolds

Miller

et al. 2016

ApJL

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We present follow-up X-ray observations of the candidate massive black hole (BH) in the nucleus of the low-mass, compact starburst galaxy Henize 2-10. Using new high-resolution observations from the Chandra X-ray Observatory totaling 200 ks in duration, as well as archival Chandra observations from 2001, we demonstrate the presence of a previously unidentified X-ray point source that is spatially coincident with the known nuclear radio source in Henize 2-10 (i.e., the massive BH). We show that the hard X-ray emission previously identified in the 2001 observation is dominated by a source that is distinct from the nucleus, with the properties expected for a high-mass X-ray binary. The X-ray luminosity of the nuclear source suggests the massive BH is radiating significantly below its Eddington limit (∼10 −6 L Edd ), and the soft spectrum resembles other weakly accreting massive BHs including Sagittarius A * . Analysis of the X-ray light curve of the nucleus reveals the tentative detection of a ∼ 9-hour periodicity, although additional observations are required to confirm this result. Our study highlights the need for sensitive high-resolution X-ray observations to probe low-level accretion, which is the dominant mode of BH activity throughout the Universe.

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Section: Observations and Data Reductionmentioning

confidence: 94%

Deep Chandra Observations of the Compact Starburst Galaxy Henize 2–10: X-Rays From the Massive Black Hole

Reines

Reynolds

Miller

et al. 2016

ApJL

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“…Most (85.2%) massive (10 10 < M/M⊙ < 10 12 ) red (W1 -W2 ≥ 0.8) galaxies in this sample are optical AGN or composites. However a growing number of AGNs have been identified in low mass galaxies (Barth et al 2004;Dong et al 2007;Greene & Ho 2007;Ghosh et al 2008;Izotov & Thuan 2008;Jiang et al 2011;Ho et al 2012;Reines & Deller 2012;Schramm et al 2013;Maksym et al 2014;Moran et al 2014;Satyapal et al 2014;Yuan et al 2014) including He2-10 (1.4×10 9 M⊙) (Reines et al 2011;Reines & Deller 2012;Whalen et al 2015), Mrk 709S (2.5×10 9 M⊙) (Reines et al 2014) and SDSS J1329+3234 (2×10 8 M⊙) (Secrest et al 2015). Reines et al (2013) has found 151 optical AGNs in galaxies with 10 8.5 < M/M⊙ < 10 9.5 , 0.6% of galaxies in this mass range.…”

Section: Agn As the Driver Of Dust Heating In Redmentioning

confidence: 99%

The luminosity and stellar mass functions of red W1–W2 galaxies

O’Connor

Rosenberg

Satyapal

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a study of nearby galaxies as a function of their [3.4]-[4.6] colour. Galaxies that are red in their [3.4]-[4.6] colour contain heated dust and the reddest systems ([3.4]-[4.6] > 0.5) are classified as AGN by some selection criteria. The sample discussed here includes nearby galaxies selected from the Sloan Digital Sky Survey (SDSS) that are also in the Wide-field Infrared Survey Explorer (WISE) catalogue. We calculate the number density of galaxies, in the form of the luminosity and mass functions, using the V/Vmax method and a Stepwise Maximum Likelihood method that has been modified to account for the additional colour selection. The reddest galaxies which have [3.4]-[4.6] > 0.8 and are sometimes classified as AGN by their colour, make up 0.2% of nearby galaxies. However, the reddest galaxies are a rising fraction of the low mass galaxy population. Identifying the lowest mass (M < 10 8 M ⊙ ) red ([3.4]-[4.6] > 0.8) galaxies as AGN is surprising given that none are optical AGN or composites, in contrast with their more massive (M > 10 10 M ⊙ ) red galaxy counterparts that are dominated by optical AGN and composites (86.4%). We also show that these low mass red galaxies are associated with higher specific star formation rates than their bluer counterparts. While the properties of this relatively rare segment of nearby low-mass galaxies are intriguing, particularly if they are associated with AGN activity, there is not yet enough evidence to determine whether it is AGN or unusual star formation that is driving red colours in these systems.

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“…However, optical data is inherently limited by dust obscuration and emission from star formation (Goulding & Alexander 2009). Both mid-IR (Satyapal et al 2008(Satyapal et al , 2009Sartori et al 2015) and radio (Reines et al 2011(Reines et al , 2014 searches have yielded complementary samples for follow-up (Whalen et al 2015;Reines & Deller 2012). In this paper, we focus on Xrays, which are insensitive to obscuration by dust and provide a relatively clean tool for identifying accreting black holes (e.g., Brandt & Alexander 2015).…”

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confidence: 99%

X-RAY DETECTED ACTIVE GALACTIC NUCLEI IN DWARF GALAXIES AT 0 < z < 1

Pardo

Goulding

Greene

et al. 2016

ApJ

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110

101

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We present a sample of accreting supermassive black holes (SMBHs) in dwarf galaxies at z < 1. We identify dwarf galaxies in the NEWFIRM Medium Band Survey with stellar masses M < 3 × 10 9 M that have spectroscopic redshifts from the DEEP2 survey and lie within the region covered by deep (flux limit of ∼ 5 × 10 −17 − 6 × 10 −16 erg cm −2 s −1 ) archival Chandra X-ray data. From our sample of 605 dwarf galaxies, 10 exhibit X-ray emission consistent with that arising from AGN activity. If black hole mass scales roughly with stellar mass, then we expect that these AGN are powered by SMBHs with masses of ∼ 10 5 − 10 6 M and typical Eddington ratios ∼ 5%. Furthermore, we find an AGN fraction consistent with extrapolations of other searches of ∼ 0.6−3% for 10 9 M ≤ M ≤ 3×10 9 M and 0.1 < z < 0.6. Our AGN fraction is in good agreement with a semi-analytic model, suggesting that as we search larger volumes we may use comparisons between observed AGN fractions and models to understand seeding mechanisms in the early universe. Subject headings: d False Detection Probability for each band -see description in Section 2.2 e All Bands in which the source is significant f Probability that the X-ray Luminosity observed could be due to an HXMB -see Section 3.2 for a full description * ≥ 3σ sources

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Variable Hard-X-Ray Emission From the Candidate Accreting Black Hole in Dwarf Galaxy Henize 2–10

Cited by 8 publications

References 34 publications

Deep Chandra Observations of the Compact Starburst Galaxy Henize 2–10: X-Rays From the Massive Black Hole

Deep Chandra Observations of the Compact Starburst Galaxy Henize 2–10: X-Rays From the Massive Black Hole

The luminosity and stellar mass functions of red W1–W2 galaxies

X-RAY DETECTED ACTIVE GALACTIC NUCLEI IN DWARF GALAXIES AT 0 < z < 1

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