Riccardo Arcodia
@ArcodiaRiccardo
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Astrophysicist - NASA Einstein Fellow @MITKavli🔭 Hobbies:🏀🪨🎸⏺️
Cambridge, MA
Joined April 2021
If QPEs are (as some models propose) the electromagnetic counterpart of extreme mass ratio inspirals (EMRI), we can use the QPE rate as a lower limit to the LISA BH-EMRI event rate! In the plot we show lower limit ranges in the case of QPEs = BH-EMRI or QPEs = stellar-EMRI.
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Since QPEs are not a one-off event, converting it to a formation rate (yaxis) depends on the unknown lifetime of the QPE behavior (xaxis). Roughly, the QPE formation rate is a factor ~(10*lifetime) smaller than that of TDEs.
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We used the first 4 QPEs discovered by @eROSITA_SRG and their detection efficiency to build a luminosity function. When integrated above a logL of 41.7, this implies a QPEs abundance rate of ~0.6 x 10^(-6) per Mpc^3, or ~0.4 x 10^(-4) per galaxy.
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📢Paper day📢 We computed the intrinsic volumetric rates of X-ray quasi-periodic eruptions: it turns out that, at any time, 1 galaxy every (roughly) 30000 out there is emitting QPEs! A 🧵.
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RT @z_igo_: Paper day! Excited to share my recently accepted paper about the incidence of radio and X-ray AGN as functions of mass-scaled p….
arxiv.org
Radio jets are present in a diverse sample of AGN. However, the mechanisms of jet powering are not fully understood, and it is yet unclear to what extent they obey mass-invariant scaling...
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Fantastic work by @joheenc! eRO-QPE1 has evolved and its eruptions are now close to the detection limit, will it rise up again?.
Belated paper day on continued NICER+XMM monitoring of eRO-QPE1, a rare source of X-ray Quasi-Periodic Eruptions (QPEs). The QPE properties show remarkable (confounding!) evolution, and we compare them to features of extreme mass-ratio inspiral models.
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RT @JohannesBuchner: Join the conference "First Results from the SRG/eROSITA All-Sky Survey: From Stars to Cosmology" Sep 15-20 in Garching….
events.mpe.mpg.de
First Results from the SRG/eROSITA All-Sky Survey: From Stars to CosmologyInternational conferenceIn little more than half a century, X-ray astronomy has established itself as a fundamental domain of...
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RT @QuantaMagazine: Erin Kara (@ErinAstro), an observational astrophysicist at MIT, is using a unique method to study black holes. In a con….
quantamagazine.org
The astrophysicist Erin Kara measures time lags in black holes’ X-ray glows, which reveal the complexity of the objects’ closest surroundings.
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This work recently appeared together with the 1st eROSITA-DE Data Release and many other @eROSITA_SRG papers, be sure to check them out!.
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3) eRO-QPE3 shows a long recurrence time and faint peak Lx, implying a lack of correlation between the two. This would disfavor the kind of accretion instabilities, or accretion-driven QPE models, which predict such correlation, e.g. if both are regulated by the black hole mass.
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2) Also the long-term evolution of eRO-QPE4 supports a short-lived nature of these systems, since its intra-QPEs emission (dark green) has appeared/brightened with/after the eruptions (light green). A pre-existing canonical AGN accretion flow in these nuclei remains disfavored.
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What’s new, based on these two new discoveries?.1) The long-term evolution of eRO-QPE3 shows a decay of both the intra-QPEs emission (red points) and the eruptions’ peak flux (orange). It supports models and data suggesting that QPEs may be revealed by precursor TDEs.
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The sample has grown to 6 sources (plus some candidates)! Surely not enough for conclusive population studies, but they already reveal a possible correlation between the average eruption duration and the average eruptions recurrence, already hinted at by the first discoveries.
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Another similarity with known QPEs is their spectral evolution: eruption rise is harder/hotter than decay at the same luminosity (see the hysteresis in the L-T plot). A strong hint of a common emission mechanism, despite their variability shows wildly different behaviors!
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Optical data from @SALT_Astro indicate z=0.024 and z=0.044 resp., and low stellar masses of their host galaxies (~1-10 billion Suns) and BH masses (~1-10 million Suns). The opt. spectra, radio and archival X-ray non-detections exclude a pre-existing strong AGN in these nuclei.
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@ESA_XMM and NICER confirmed their nature. Top shows XMM data of eRO-QPE3 (eruptions every ~20.4h); bottom XMM for eRO-QPE4, with a shorter (~9.8h) and longer (~14.7h) recurrence. For both sources, NICER data favor a scatter of recurrence times rather than a pure alternation.
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The two new discoveries, named eRO-QPE3 and eRO-QPE4 among friends, popped up due to their remarkable variability within the eROSITA all-sky survey data. Here you can see an example for eRO-QPE4, with all X-ray counts in a single snapshot of the full light curve.
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📢New paper!📢 We published the discovery, with @eROSITA_SRG, of two more galaxies showing the repeated X-ray flares called quasi-periodic eruptions (QPEs). So. what’s new on QPEs? A 🧵.
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RT @andmerloni: In less than 24 hours we'll be releasing all the Data from the First @eROSITA_SRG all-sky survey, including the largest X-r….
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