The first interferometric detections of fast radio bursts
Summary (4 min read)
Introduction
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I. THE CURRENT DISCOURSE
- Driven by concerns about the educational quality and ideological orientation of the public schools, parents have sought increasing control over their children's education through the political process and in the courts.
- Under all of these approaches, the state maintains some control over the curricular content of the child's education while relinquishing control over the child's peer associations.
- At the same time, schools were coming under increasing attack by organizations associated with religious conservatives for their secular humanist teachings,2 and their promotion of "tolerance,"3 which 1 National Commission on Excellence in Education, A Nation at Risk.
- Increasingly, states are abandoning educational requirements, such as certification, that made it difficult or impossible for parents to home school their children,7 and replacing such requirements with regulations designed to serve the limited purpose of ensuring that children acquire the basic knowledge and academic skills offered in school.
10 Id at 1338 (reporting that thirteen states allow an exemption from the compulsory attendance laws for children receiving "equivalent instruction," and describing equivalency in substantive terms).
- Where the Kitchen is Also the Classroom, NY Times Gi (Oct 29, 1998) (noting that the estimates of the number of home-schooled children range from 1 million to 1.6 million, and stating that the numbers have tripled in the past decade).
- See Bagley v Raymond School Department, 728 A2d 127,130-31 (Me 1999) (remarking that Maine does not allow voucher money to be used towards religious private education); Chittenden Town School District v Department of Education, 738 A2d 539,542-44 (Vt 1999) (observing that parents cannot use school vouchers in Vermont to pay for parochial or sectarian schools).
- Like voucher and home-schooling programs, charter-school initiatives impose certain substantive performance criteria on the new schools,16 and unlike the other approaches, these initiatives sometimes require that the racial proportions in the charter schools match those in the public schools to prevent charter schools from becoming sites for de facto segregation.".
- Even if children are assumed to have rights coextensive with those of adults, however, the Court's decision in Smith suggests that a religious objection to a state's facially neutral educational requirement would not justify an exemption if not accompanied by a claim of a due process right of parental control.
The Adolescent's Stake
- Elude the ability to engage in an occupation or otherwise support oneself, as well as the ability to participate responsibly in public activities, including the democratic process.
- Many theorists suggest that success should also be defined to include the ability to exercise independent judgment when making important life choices, a goal largely unaddressed in this context by the courts.
- First, it suggests that any threat posed to parental control by children's exposure to unlike peers comes with considerable compensating developmental benefits to the individual child.
1995) (challenging school's requirement that plaintiff children attend an assembly that included crude sexual gestures and remarks).
- 52 See, for example, Mozert v Hawkins County Board of Education, 827 F2d 1058 (6th Cir 1987) (challenging required reading of texts parents found offensive to their religious beliefs).
- 54 See, for example, Brown, 68 F3d at 529 (challenging attendance requirement at a single assembly); Curtis, 652 NE2d at 580 (seeking authority only to restrict the access of their children to condoms without their consent).
- Note that the parents' claims are not always narrowly limited to a request for a child-specific exemption to particular material.
- In some cases, the parents seek to eliminate objectionable material from the curriculum altogether.
My ultimate task, which I will take up in Part III, is to consider
- How, if at all, a more sophisticated understanding of child development changes how the authors should analyze parents' attempts to control their children's education, particularly for religious reasons.
- Before digging into the developmental literature, I wish to consider the appropriateness of this interdisciplinary inquiry.
- Put simply, an understanding of development is important because the law affecting children is grounded on developmental assumptions.u.
- The law frequently treats children differently from adults,.
80 In analyzing the law as it applies to children, developmental assumptions come into play
- In two ways that roughly correlate with discussions of children's legal rights, on the one hand, and children's needs and interests, on the other.
- The term "development" is increasingly used to describe the ongoing process of change over the course of a lifetime.
- The second category of objections focuses on sampling issues, and the role context, and particularly cultural context, plays in shaping how studies are designed, what results are obtained, and how those results are interpreted.".
- 89 Understanding children's development can lead to more sophisticated lawmaking on several levels: most obviously, to the extent legal rules are grounded exclusively on developmental assumptions, a better understanding of development will produce better justified rules and, where assumptions are shown to be incorrect, better rules.
- The developmental inquiry can have other beneficial analytic effects: where developmental effects point in one direction, but the law in another, the developmental inquiry may help to illuminate what other considerations are at stake, and what relative weight is being afforded to these various considerations.
96 Id at 180 (noting that "[a]n inability to examine several possible identity alternatives"
- While there is considerable variation among the cultural groups represented in their cases, adolescence in all these cultures is a period during which individuals prepare for, but do not for the most part yet undertake, adult responsibilities.
- Building upon Erikson's theories, James Marcia suggested that the identity formation process reflects development along two different axes: the experience of crisis (doubt and indecision accompanied by an awareness of multiple competing possibilities) and the undertaking of commitments (resolution of these doubts and selection among the possibilities).
- Individuals who have confronted the crisis but not yet undertaken commitments were labeled moratoriums.
- See also Kroger, Identity in Adolescence at 13-46 (cited in note 91) (setting out the link between identity formation and subsequent preparedness for intimacy, in Erikson's stage scheme of crises and resolutions).
To assist with this developmental shift, adolescents turn from
- This is not to say that parents lose all influence over their children's identity choices.
- It is with peers that adolescents spend an increasing portion of their time '" and share confidences,"' and it is through these peer interactions that much of their identity development occurs.-".
- Who the authors choose as friends tells their broader social group something about their values, talents and tastes,' and the way others perceive us affects how they relate to us.
On the level of cognitive development, peer interactions facilitate
- The adolescent's ability to engage in reflection about her own identity.
- See, for example, Hamachek, Development and Dynamics of the Self at 162 (cited in note 131) (teenagers are more likely to rely on their own judgment than on the advice of either peers or parents).
- Where a parent limits the pool of peers to those raised in the parent's own traditions, the child's choice of peers, the self-reflection facilitated by peers, and the emotional support provided by peers in that pool will all help to point the child in the direction of the parent's ideologies and affiliations."".
- Because identity formation is such an important preparatory step toward adulthood,"n and because peers play such an important role in assisting adolescents to take that step, those with the responsibility for children's development-state and parent alike-have every reason to be concerned about who those peers are and the nature of those interactions.
CONCLUSION
- At the most basic level, the state's interest, like a parent's, is in preparing the child for a successful adulthood-successful in the eyes of society, the parent, and the child.
- Success will surely in- Athletic Association, 1995 Mass Super LEXIS 791 (enjoining athletic association and school district from excluding home-schooled child from athletic participation).
- 186 See Brown, Peer Groups and Peer Cultures at 180 (cited in note 128) (noting that adolescents, left to their own devices, will seek out peers who are similar to themselves).
- 187 Entwisle, Schools and the Adolescent at 213 (cited in note 79) (discussing the value of cooperative learning techniques, where children of mixed-race groups engage in noncompetitive problem solving, for improving achievement, self-esteem, and intergroup relations).
- These techniques were first championed by Gordon W. Allport in his seminal work, The Nature of Prejudice (Addison-Wesley 1954).
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Citations
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339 citations
Cites methods from "The first interferometric detection..."
...Searches for FRBs at the Parkes telescope and with the UTMOST telescope in Australia have primarily been done with the heimdall18 pipeline, which uses brute force dedispersion techniques on GPUs (Champion et al. 2016; Caleb et al. 2017)....
[...]
...Searches for FRBs at the Parkes telescope and with the UTMOST telescope in Australia have primarily been done with the heimdall pipeline, which uses brute force dedispersion techniques on GPUs (Champion et al., 2016; Caleb et al., 2017)....
[...]
320 citations
Cites background from "The first interferometric detection..."
...There is also evidence that the FRB rate at low frequencies ν < 700 MHz is lower than at 1.4 GHz (Karastergiou et al. 2015; Rowlinson et al. 2016; Burke-Spolaor et al. 2016; Caleb et al. 2017; Chawla et al. 2017; Sokolowski et al. 2018)....
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245 citations
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225 citations
212 citations
Cites background from "The first interferometric detection..."
...◦8 (see Caleb et al. 2017 for the details of this observing mode)....
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...…(Lorimer et al. 2007; Keane et al. 2012; Thornton et al. 2013; Burke-Spolaor & Bannister 2014; Spitler et al. 2014; Masui et al. 2015; Petroff et al. 2015a, 2017; Ravi, Shannon & Jameson 2015; Champion et al. 2016; Keane et al. 2016; Ravi et al. 2016; Caleb et al. 2017; Bannister et al. 2017)....
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References
2,415 citations
Additional excerpts
...Based on this, we measure a detectable event rate of (R), R (F 11 Jy ms) 0.78+1.24−0.57 × 102 events sky−1 d−1 (4) at the 95 per cent confidence level (Gehrels 1986), above a full power boresight fluence of 11 Jy ms as parametrized by equation (2), at the half-power FoV....
[...]
1,644 citations
"The first interferometric detection..." refers background in this paper
...The pulses are typically of durations of a few milliseconds, and exhibit a dispersion sweep characteristic of propagation through a cold diffuse plasma E-mail: manishacaleb@gmail.com (Lorimer et al. 2007; Thornton et al. 2013)....
[...]
...For instance, ≈80 h of follow up for the Lorimer burst (Lorimer et al. 2007), ≈80 h for FRB 131104 (Ravi, Shannon & Jameson 2015) and ≈110 h of selected FRB positions (Petroff et al. 2015) at the Parkes radio telescope yielded no repeats....
[...]
1,137 citations
1,093 citations
"The first interferometric detection..." refers background in this paper
...The pulses are typically of durations of a few milliseconds, and exhibit a dispersion sweep characteristic of propagation through a cold diffuse plasma E-mail: manishacaleb@gmail.com (Lorimer et al. 2007; Thornton et al. 2013)....
[...]
883 citations
"The first interferometric detection..." refers background in this paper
...However, one FRB is now known to repeat in a non-periodic manner (FRB 121102; Spitler et al. 2016), opening up possibilities for other progenitor models....
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...We note that the repeat FRB pulses from the Arecibo FRB 121102 exhibit a wide range of spectral indices (γ ∼ −10 to +14; Spitler et al. 2016), similar to giant pulses from the Crab pulsar....
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Frequently Asked Questions (13)
Q2. What makes the UTMOST a near ideal survey instrument?
The telescope’s field of view, sensitivity and high duty cycle make it a near ideal survey instrument for finding FRBs and other radio transients.
Q3. How much S/N is concentrated in the upper half of the band?
The authors find that on average ∼86 per cent of the total S/N is concentrated in the upper half of the band (∼836–850) as the antennas are tuned to maximum sensitivity at 843 MHz.
Q4. How many events can be detected at CHIME?
The authors expect CHIME to detect ∼70 events beam−1 d−1 for Tsys = 50 K, S/N =10, G = 1.38 K Jy−1, Np = 2 and FoV = 250 deg2 (Connor et al. 2016a; Ng et al. 2017).
Q5. How long has the UTMOST been used to search for radio transients?
Since late 2015, the authors have been using UTMOST to search for fast radio transients for an average of 18 h a day, while simultaneously timing more than 300 pulsars weekly (Bailes et al., in preparation, Jankowski et al., in preparation).
Q6. What is the advantage of the array?
4. The primary advantage of the array is that a pulse from a far-field point source is detected in a maximum of three adjacent FBs at any given time, confirmed by extensive pulsar observations.
Q7. How does the telescope access the southern sky?
The telescope can access the southern sky for δ < +18◦, and for most parts of the sky the authors tend to observe reasonably close to the meridian, in order to maximize sensitivity.
Q8. How many events are detected at UTMOST?
Based on the time spent on sky and the number of detections made, the authors measure a rate of 0.017+0.03−0.01 events beam−1 d−1 at UTMOST, for the sensitivity achieved during the upgrade.
Q9. How many ms is the fluence limit of the survey?
Their fluence limit of the survey, that is the fluence of the narrowest detectable pulse Flim can be parametrized as Flim ≈ 11 ( Wms)1/2 Jy ms (2)where, 11 Jy is the UTMOST flux limit for S/N = 10, G = 3.0 K Jy−1, ν = 16 MHz, W = 1 ms, Np = 1 and Tsys = 400 K.
Q10. What is the true positive rate at UTMOST?
The false positive rate at UTMOST is high due to RFI caused by mobile phone handsets, which produce narrow band (5-MHz) emission in their band, typically in ≈20 ms pulses.
Q11. How do the authors quantify the tension between the probability of observing three or more events?
The authors quantify this tension by calculating the probability of observing three or more events to be 14.3 per cent, assuming Poisson statistics with a mean of 1.3.
Q12. What is the process used to determine the FRB candidates?
The process followed is:(i) obtain 352 data streams (8-bits/sample), one for each FB, at 655.36-µs sampling;(ii) search time series for single pulses with width, 0.655 36 < W < 41.943 ms (W = 2N × 0.655 36 ms, where N = 0,1,2,...) and DMs in the range 100 < DM < 2000 pc cm−3;(iii) remove events occurring simultaneously in more than three FBs at a given instant in time;(iv) classify only events with S/N ≥10, DM ≥100 pc cm−3 and W ≤ 41.943 ms as potential FRB candidates.
Q13. How many channels can be used to detect FRBs?
The authors havenow implemented a fine channel mode (320 channels) that will potentially increase their sensitivity and the FRB detection rate by a factor of √